From: Michael Zucchi <michael@swordfish.com.au>
Date: Sun, 12 May 2019 09:14:00 +0000 (+0930)
Subject: VideoPlay demo enhancements
X-Git-Url: https://code.zedzone.au/cvs?a=commitdiff_plain;h=813fb32b886b4c7c74ec23d7d0988d67b6992305;p=jjmpeg

VideoPlay demo enhancements
Make sure jni library is loaded for non-AVObject derived static methods.
Checkpoint ongoing work on doc improvements
Checkpoint ongoing work on accessor cleanup
Auto-generate some of the AVIOContext flags
AVIOContext improvements
JJMediaWriter improvements
Attach all threads as daemons in jni
Change AVPacket interface for accessing data buffer
---

diff --git a/src/notzed.jjmpeg.demo/classes/au/notzed/jjmpeg/demo/video/VideoPlay.java b/src/notzed.jjmpeg.demo/classes/au/notzed/jjmpeg/demo/video/VideoPlay.java
index a2252d8..112c761 100644
--- a/src/notzed.jjmpeg.demo/classes/au/notzed/jjmpeg/demo/video/VideoPlay.java
+++ b/src/notzed.jjmpeg.demo/classes/au/notzed/jjmpeg/demo/video/VideoPlay.java
@@ -24,21 +24,25 @@ import au.notzed.jjmpeg.io.JJMediaReader;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import static java.lang.Double.min;
-import java.text.SimpleDateFormat;
-import java.util.Date;
+import java.time.Instant;
+import java.time.LocalTime;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
 import java.util.List;
-import java.util.TimeZone;
 import java.util.concurrent.CountDownLatch;
 import javafx.application.Application;
 import javafx.application.Platform;
 import javafx.beans.InvalidationListener;
 import javafx.beans.Observable;
 import javafx.geometry.Insets;
+import javafx.geometry.Rectangle2D;
 import javafx.scene.Scene;
 import javafx.scene.control.Alert;
 import javafx.scene.control.ButtonType;
 import javafx.scene.image.ImageView;
 import javafx.scene.image.WritableImage;
+import javafx.scene.input.KeyCode;
+import javafx.scene.input.KeyCodeCombination;
 import javafx.scene.layout.AnchorPane;
 import javafx.scene.layout.Background;
 import javafx.scene.layout.BackgroundFill;
@@ -47,6 +51,7 @@ import javafx.scene.paint.Color;
 import javafx.scene.text.Text;
 import javafx.scene.transform.Scale;
 import javafx.scene.transform.Translate;
+import javafx.stage.Screen;
 import javafx.stage.Stage;
 
 /**
@@ -87,7 +92,7 @@ public class VideoPlay extends Application {
 	WritableImage image;
 	Text label;
 	Stage stage;
-	SimpleDateFormat time;
+	DateTimeFormatter time;
 	long time0 = -1;
 	long stamp0;
 
@@ -96,8 +101,7 @@ public class VideoPlay extends Application {
 		height = vs.getHeight();
 		frameReader = new FXPixelReader(vs.getFrame().getPixelReader(width, height, 0));
 
-		time = new SimpleDateFormat("HH:mm:ss.SSS");
-		time.setTimeZone(TimeZone.getTimeZone("GMT"));
+		time = DateTimeFormatter.ofPattern("HH:mm:ss.SSS");
 
 		Platform.runLater(() -> {
 			label = new Text();
@@ -115,7 +119,20 @@ public class VideoPlay extends Application {
 
 			ap.setBackground(new Background(new BackgroundFill(Color.BLACK, CornerRadii.EMPTY, Insets.EMPTY)));
 
-			Scene scene = new Scene(ap, width, height);
+			Rectangle2D bounds = Screen.getPrimary().getVisualBounds();
+			double swidth = bounds.getWidth() - 32;
+			double sheight = bounds.getHeight() - 32;
+			Scene scene;
+			if (width > swidth || height > sheight) {
+				double scalex = swidth / width;
+				double scaley = sheight / height;
+
+				swidth = scalex < scaley ? swidth : width * scaley;
+				sheight = scalex < scaley ? height * scalex : sheight;
+				scene = new Scene(ap, swidth, sheight);
+			} else {
+				scene = new Scene(ap, width, height);
+			}
 
 			stage = new Stage();
 			stage.setScene(scene);
@@ -145,6 +162,12 @@ public class VideoPlay extends Application {
 
 			ap.widthProperty().addListener(fitVideo);
 			ap.heightProperty().addListener(fitVideo);
+			fitVideo.invalidated(null);
+
+			scene.getAccelerators().put(new KeyCodeCombination(KeyCode.Q), () -> {
+				cancel = true;
+				stage.close();
+			});
 		});
 	}
 
@@ -161,7 +184,8 @@ public class VideoPlay extends Application {
 	 * @param stamp
 	 */
 	void videoFrame(JJMediaReader.JJReaderVideo vs, long stamp) {
-		String ts = time.format(new Date(stamp));
+		Instant x = Instant.ofEpochMilli(stamp + vs.getStartMS());
+		String ts = time.format(LocalTime.ofInstant(x, ZoneId.of("UTC")));
 		CountDownLatch latch = new CountDownLatch(1);
 
 		// Display the frame.  Must run on javafx thread.
@@ -196,9 +220,11 @@ public class VideoPlay extends Application {
 	 * @param x
 	 */
 	void videoError(IOException x) {
-		Alert a = new Alert(Alert.AlertType.ERROR, x.getLocalizedMessage(), ButtonType.CLOSE);
-		a.showAndWait();
-		Platform.exit();
+		Platform.runLater(() -> {
+			Alert a = new Alert(Alert.AlertType.ERROR, x.getLocalizedMessage(), ButtonType.CLOSE);
+			a.showAndWait();
+			Platform.exit();
+		});
 	}
 
 	volatile boolean cancel = false;
@@ -226,6 +252,7 @@ public class VideoPlay extends Application {
 			}
 
 		} catch (AVIOException | FileNotFoundException ex) {
+			ex.printStackTrace();
 			videoError(ex);
 		}
 	}
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVChannelLayout.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVChannelLayout.java
index aed143a..9a8bbd3 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVChannelLayout.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVChannelLayout.java
@@ -20,7 +20,11 @@ package au.notzed.jjmpeg;
 
 /**
  */
-public class AVChannelLayout extends AVObject implements AVChannelLayoutBits {
+public class AVChannelLayout implements AVChannelLayoutBits {
+
+	static {
+		AVObject.init();
+	}
 
 	/**
 	 * Call av_get_channel_layout(name)
@@ -48,7 +52,4 @@ public class AVChannelLayout extends AVObject implements AVChannelLayoutBits {
 	 */
 	public static native long getDefaultLayout(int nchannels);
 
-	private AVChannelLayout(long p) {
-		super(p);
-	}
 }
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodec.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodec.java
index 38fe130..cd1356e 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodec.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodec.java
@@ -51,15 +51,34 @@ public class AVCodec extends AVObject implements AVCodecBits, AVDiscardBits {
 
 	public static native AVCodec findEncoder(String name);
 
-	/*
-	Accessors
+	/**
+	 * Get AVCodec.name.
+	 *
+	 * @return
 	 */
 	public native String getName();
 
+	/**
+	 * Get AVCodec.long_name.
+	 *
+	 * @return
+	 */
 	public native String getLongName();
 
+	/**
+	 * Get AVCodec.type.
+	 *
+	 * @return
+	 * @see AVMediaType
+	 */
 	public native int getType();
 
+	/**
+	 * Get AVCodec.id.
+	 *
+	 * @return
+	 * @see AVCodecID
+	 */
 	public native int getID();
 
 	public native int getCapabilities();
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodecContext.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodecContext.java
index 9e5e8e5..d3fae47 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodecContext.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodecContext.java
@@ -21,6 +21,14 @@ package au.notzed.jjmpeg;
 /**
  * AVCodecContext accessors.
  * <p>
+ * The accessors here are currently implemented as direct struct accessors but
+ * most fields may also be accessed by the {@link AVOptions} accessor methods. The
+ * AVOptions methods are somewhat inconvenient but provide additional
+ * validation checks for setting options.
+ * <p>
+ * Note that there are many other options, these are documented in libavcodec/avcodec.h and the ffmpeg
+ * source in libavcodec/options_table.h. This can also be retrieved at runtime
+ * via
  */
 public class AVCodecContext extends AVOptions implements AVCodecContextBits {
 
@@ -28,46 +36,84 @@ public class AVCodecContext extends AVOptions implements AVCodecContextBits {
 		super(p);
 	}
 
+	/**
+	 * Free the context.
+	 * <p>
+	 * Calls avcodec_free_context().
+	 *
+	 * @param p
+	 */
 	private static native void release(long p);
 
-	/*
-	 * Methods
-	 */
 	/**
+	 * Allocate and initialise an AVCodecContext.
+	 * <p>
+	 * Calls avcodec_alloc_context3().
 	 *
-	 * @param codec
+	 * @param codec Codec used to initialise parameters, may be null.
 	 * @return
 	 */
 	public static native AVCodecContext allocContext(AVCodec codec);
 
-	// avcodec_open2
+	/**
+	 * Open a context.
+	 * <p>
+	 * Calls avcodec_open2().
+	 *
+	 * @param codec Codec used. It must match the one used in allocContext().
+	 * @param options Codec options.
+	 * @throws AVIOException is thrown iv avcodec_open2 returns an error.
+	 */
 	public native void open(AVCodec codec, AVDictionary options) throws AVIOException;
 
+	/**
+	 * Flush internal buffers.
+	 * <p>
+	 * Used to reset codec state, for example after a seek.
+	 * <p>
+	 * Calls avcodec_flush_buffers().
+	 */
 	public native void flushBuffers();
 
+	/**
+	 * Align dimensions suitable for codec.
+	 * <p>
+	 * Calls avcodec_align_dimensions().
+	 *
+	 * @param input Input dimensions.
+	 * @return Modified dimensions.
+	 */
 	public native AVSize alignDimensions(AVSize input);
-	
+
 	/**
-	 * Calls avcodec_send_packet()
+	 * Submit raw packet to a decoder.
+	 * <p>
+	 * Packets are submitted to a decoder which generates output frames.
 	 * <p>
 	 * If the return value is EAGAIN or AVERROR_EOF then this function
 	 * returns false, for all other error values it throws an exception.
+	 * <p>
+	 * Calls avcodec_send_packet().
 	 *
 	 * @param pkt
 	 * @return true if the packet was accepted, false if a frame must be received first.
 	 * @throws AVIOException
+	 * @see #receiveFrame(au.notzed.jjmpeg.AVFrame)
 	 */
 	public native boolean sendPacket(AVPacket pkt) throws AVIOException;
 
 	/**
-	 * Calls avcodec_receive_frame().
+	 * Retrieve a decoded frame from a decoder.
 	 * <p>
-	 * If the return value is EAGAIN or AVERROR_EOF then this function
-	 * returns false, for all other error values it throws an exception.
+	 * If the return value from avcodec_receive_frame() is EAGAIN or AVERROR_EOF
+	 * then this function returns false, for all other error values it throws an exception.
+	 * <p>
+	 * Calls avcodec_receive_frame().
 	 *
 	 * @param frame
 	 * @return Returns true if the frame is complete, false otherwise.
 	 * @throws AVIOException
+	 * @see #sendPacket(au.notzed.jjmpeg.AVPacket)
 	 */
 	public native boolean receiveFrame(AVFrame frame) throws AVIOException;
 
@@ -95,203 +141,346 @@ public class AVCodecContext extends AVOptions implements AVCodecContextBits {
 	 */
 	public native boolean receivePacket(AVPacket pkt) throws AVIOException;
 
-	/*
-	 * Accessors
+	/**
+	 * Get encoding/decoding AVCodecContext.codec_type.
+	 *
+	 * @return
+	 * @see AVMediaType
 	 */
 	public native int getCodecType();
 
+	/**
+	 * Set encoding/decoding AVCodecContext.codec_type.
+	 *
+	 * @param val
+	 * @see AVMediaType
+	 */
 	public native void setCodecType(int val);
 
+	/**
+	 * Get encoding/decoding AVCodecContext.codec_id.
+	 *
+	 * @return
+	 * @see AVCodecID
+	 */
 	public native int getCodecID();
 
+	/**
+	 * Set encoding/decoding AVCodecContext.codec_id.
+	 *
+	 * @param val
+	 * @see AVCodecID
+	 */
 	public native void setCodecID(int val);
 
-	public native int getCodecTag();
-
-	public native void setCodecTag(int val);
-
+	/**
+	 * Get encoding/decoding AVCodecContext.bit_rate.
+	 * <p>
+	 * AVOption int "b" or "ab"
+	 *
+	 * @return
+	 */
 	public native long getBitRate();
 
-	public native void setBitRate(long val);
-
-	public native int getBitRateTolerance();
-
-	public native void setBitRateTolerance(int val);
+	/**
+	 * Set encoding/decoding AVCodecContext.bit_rate.
+	 * <p>
+	 * AVOption int "b" or "ab"
+	 *
+	 * @param bitrate
+	 */
+	public native void setBitRate(long bitrate);
 
+	/**
+	 * Get encoding AVCodecContext.global_quality.
+	 * <p>
+	 * AVOption int "global_quality".
+	 *
+	 * @return
+	 */
 	public native int getGlobalQuality();
 
-	public native void setGlobalQuality(int val);
-
-	public native int getCompressionLevel();
-
-	public native void setCompressionLevel(int val);
+	/**
+	 * Set AVCodecContext.global_quality.
+	 * <p>
+	 * AVOption int "global_quality".
+	 *
+	 * @param quality
+	 */
+	public native void setGlobalQuality(int quality);
 
 	/**
-	 * Get the contents of flags and flags2 together as a single 64-bit value.
+	 * Get the encoding/decoding AVCodecContext.flags and AVCodecContext.flags2.
+	 * <p>
+	 * This combines .flags and .flags2 into a single 64-bit flag set. The
+	 * AV_CODE_FLAG2_* constants have been shifted appropriately.
+	 * <p>
+	 * AVOption int "flag", also specific flags "unaligned", "mv4", and so on.
 	 *
 	 * @return
 	 */
 	public native long getFlags();
 
 	/**
-	 * Set or clear flags and flags2.
+	 * Adjust the encoding/decoding AVCodecContext.flags and AVCodecContext.flags2.
+	 * <p>
+	 * This performs a combined get and set operation on the flags allowing any cobimation
+	 * of flags to be set in a single call.
+	 * <p>
+	 * AVOption int "flag", also specific flags "unaligned", "mv4", and so on.
 	 *
-	 * @param mask Mask of bits to change. Only flags with a bit set here will be altered.
+	 * @param mask Mask of bits to change. Flags with a bit set here will be set to the values in flags.
 	 * @param flags Value to set bits to.
+	 * @see #getFlags() for an explanation of the flag values.
 	 */
 	public native void setFlags(long mask, long flags);
 
 	/**
-	 * Get the timebase.
+	 * Get the encoding AVCodecContext.time_base.
 	 * <p>
-	 * Note that the return value is a value type (copy) not a reference.
+	 * AVOption rational (q) "time_base".
 	 *
-	 * @return
+	 * @return A copy of the time_base (adjustments will not be carried through).
 	 */
 	public native AVRational getTimeBase();
 
-	public native void setTimeBase(AVRational val);
-
-	public native int getTicksPerFrame();
-
-	public native void setTicksPerFrame(int val);
+	/**
+	 * Set the encoding AVCodecContext.time_base.
+	 * <p>
+	 * A time_base must always be set for encoding.
+	 * <p>
+	 * AVOption rational (q) "time_base".
+	 *
+	 * @param timebase
+	 */
+	public native void setTimeBase(AVRational timebase);
 
+	/**
+	 * Get the encoding/decoding AVCodecContext.delay.
+	 * <p>
+	 * AVOption int "delay".
+	 *
+	 * @return
+	 */
 	public native int getDelay();
 
-	/*
-		Video only options
+	/**
+	 * Get video encoding/decoding AVCodecContext.width.
+	 * <p>
+	 * AVOption image size "video_size".
+	 *
+	 * @return
 	 */
 	public native int getWidth();
 
-	public native void setWidth(int val);
+	/**
+	 * Set video encoding/decoding AVCodecContext.width.
+	 * <p>
+	 * AVOption image size "video_size".
+	 *
+	 * @param width
+	 */
+	public native void setWidth(int width);
 
+	/**
+	 * Get video encoding/decoding AVCodecContext.height.
+	 * <p>
+	 * AVOption image size "video_size".
+	 *
+	 * @return
+	 */
 	public native int getHeight();
 
-	public native void setHeight(int val);
+	/**
+	 * Set video encoding/decoding AVCodecContext.width.
+	 * <p>
+	 * AVOption image size "video_size".
+	 *
+	 * @param height
+	 */
+	public native void setHeight(int height);
 
+	/**
+	 * Get video encoding/decoding AVCodecContext.sample_aspect_ratio.
+	 * <p>
+	 * AVOption rational "aspect" or "sar".
+	 *
+	 * @return
+	 */
 	public native AVRational getAspectRatio();
 
-	public native void setAspectRatio(AVRational r);
+	/**
+	 * Set video encoding/decoding AVCodecContext.sample_aspect_ratio.
+	 * <p>
+	 * AVOption rational "aspect" or "sar".
+	 *
+	 * @param ratio
+	 */
+	public native void setAspectRatio(AVRational ratio);
 
-	// codedWidth, codedHeight
+	/**
+	 * Get video encoding AVCodecContext.gop_size.
+	 * <p>
+	 * AVOption int "g".
+	 *
+	 * @return
+	 */
 	public native int getGOPSize();
 
+	/**
+	 * Set video encoding AVCodecContext.gop_size.
+	 * <p>
+	 * AVOption int "g".
+	 *
+	 * @param val
+	 */
 	public native void setGOPSize(int val);
 
+	/**
+	 * Get video encoding/decoding AVCodecContext.pix_fmt.
+	 * <p>
+	 * AVOption pixel format "pixel_format".
+	 *
+	 * @return
+	 * @see AVPixelFormat
+	 */
 	public native int getPixelFormat();
 
-	public native void setPixelFormat(int val);
-
-	//
-	public native int getMaxBFrames();
-
-	public native void setMaxBFrames(int val);
-
-	public native float getBQuantFactor();
-
-	public native void setBQuantFactor(float val);
-
-	public native float getBQuantOffset();
-
-	public native void setBQuantOffset(float val);
-
-	public native boolean hasBFrames();
-
-	public native float getIQuantFactor();
-
-	public native void setIQuantFactor(float val);
-
-	public native float getIQuantOffset();
-
-	public native void setIQuantOffset(float val);
-// And a whole lot more ...
-//	
-
-	public native int getMBDecision();
-
-	public native void setMBDecision(int val);
-// ...
+	/**
+	 * Set video encoding/decoding AVCodecContext.pix_fmt.
+	 * <p>
+	 * AVOption pixel format "pixel_format".
+	 *
+	 * @param format
+	 * @see AVPixelFormat
+	 */
+	public native void setPixelFormat(int format);
 
-	/*
-		Audtio only options
+	/**
+	 * Get audio encoding/decoding AVCodecContext.sample_rate.
+	 * <p>
+	 * AVOption int "ar".
+	 *
+	 * @return
 	 */
 	public native int getSampleRate();
 
-	public native void setSampleRate(int val);
+	/**
+	 * Set audio encoding/decoding AVCodecContext.sample_rate.
+	 * <p>
+	 * AVOption int "ar".
+	 *
+	 * @param hertz
+	 */
+	public native void setSampleRate(int hertz);
 
+	/**
+	 * Get audio encoding/decoding AVCodecContext.channels.
+	 * <p>
+	 * AVOption int "ac".
+	 *
+	 * @return
+	 */
 	public native int getNumChannels();
 
-	public native void setNumChannels(int val);
+	/**
+	 * Set audio encoding/decoding AVCodecContext.channels.
+	 * <p>
+	 * AVOption int "ac".
+	 *
+	 * @param nchannels
+	 */
+	public native void setNumChannels(int nchannels);
 
+	/**
+	 * Get audio encoding/decoding AVCodecContext.sample_fmt.
+	 *
+	 * @return
+	 * @see AVSampleFormat
+	 */
 	public native int getSampleFormat();
 
-	public native void setSampleFormat(int val);
+	/**
+	 * Set audio encoding/decoding AVCodecContext.sample_fmt.
+	 *
+	 * @param format
+	 * @see AVSampleFormat
+	 */
+	public native void setSampleFormat(int format);
 
+	/**
+	 * Get audio encoding/decoding AVCodecContext.frame_size.
+	 * <p>
+	 * AVOption int "frame_size".
+	 *
+	 * @return
+	 */
 	public native int getFrameSize();
 
-	public native void setFrameSize(int val);
-
+	/**
+	 * Get audio encoding/decoding AVCodecContext.frame_number.
+	 * <p>
+	 * AVOption int "frame_number".
+	 *
+	 * @return
+	 */
 	public native int getFrameNumber();
 
-// int block_align
-// int cutoff
+	/**
+	 * Get audio encoding/decoding AVCodecContext.channel_layout.
+	 * <p>
+	 * AVOption channel layout "channel_layout".
+	 *
+	 * @return
+	 * @see AVChannelLayout
+	 */
 	public native long getChannelLayout();
 
-	public native void setChannelLayout(long val);
+	/**
+	 * Set audio encoding/decoding AVCodecContext.channel_layout.
+	 * <p>
+	 * AVOption channel layout "channel_layout".
+	 *
+	 * @param layout
+	 * @see AVChannelLayout
+	 */
+	public native void setChannelLayout(long layout);
 
+	/**
+	 * Get audio decoding AVCodecContext.request_channel_layout.
+	 * <p>
+	 * AVOption channel layout "request_channel_layout".
+	 *
+	 * @return
+	 * @see AVChannelLayout
+	 */
 	public native long getRequestChannelLayout();
 
-	public native void setRequestChannelLayout(long val);
-
-//  enum AVAudioServiceType audio_service_type
-//	enum AVSampleFormat request_sample_fmt;
-
-	/*
-	Encoding parameters
+	/**
+	 * Set audio decoding AVCodecContext.request_channel_layout.
+	 * <p>
+	 * AVOption channel layout "request_channel_layout".
+	 *
+	 * @param layout
+	 * @see AVChannelLayout
 	 */
-// float qcompress
-// float qblur
-// float qmin
-// float qmax
-// float max_qdiff
-// int rc_buffer_size
-// int rc_override_count
-// RCOverride *rc_override
-// int64_t rc_max_rate
-// int64_t rc_min_rate
-// ... more rc stuff
-// ...
-// int trellis
-// ...
-// int workaround_bugs
-	public native int getStrictStdCompliance();
-
-	public native void setStrictStdCompliance(int val);
-
-	public native int getErrorConcealment();
-
-	public native void setErrorConcealment(int val);
-// int debug
-
-	public native int getErrorRecognition();
-
-	public native void setErrorRecognition(int val);
-
-	public native int getDCTAlgo();
-
-	public native void setDCTAlgo(int val);
-
-	public native int getIDCTAlgo();
-
-	public native void setIDCTAlgo(int val);
+	public native void setRequestChannelLayout(long layout);
 
+	/**
+	 * Get encoding/decoding AVCodecContext.thread_count.
+	 * <p>
+	 * AVOption int "threads".
+	 *
+	 * @return
+	 */
 	public native int getThreadCount();
 
-	public native void setThreadCount(int val);
-// ...
-
-	public native int getProfile();
-
-	public native void setProfile(int val);
-// ...
+	/**
+	 * Set encoding/decoding AVCodecContext.thread_count.
+	 * <p>
+	 * AVOption int "threads".
+	 *
+	 * @param nthreads
+	 */
+	public native void setThreadCount(int nthreads);
 }
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodecID.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodecID.java
index 46b21b7..ab39bb8 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodecID.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVCodecID.java
@@ -22,6 +22,10 @@ package au.notzed.jjmpeg;
  */
 public class AVCodecID implements AVCodecIDBits {
 
+	static {
+		AVObject.init();
+	}
+
 	/**
 	 * Call avcodec_get_name(value)
 	 */
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVError.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVError.java
index b374db7..7367b51 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVError.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVError.java
@@ -22,6 +22,10 @@ package au.notzed.jjmpeg;
  *
  */
 public class AVError implements AVErrorBits {
-	
+
+	static {
+		AVObject.init();
+	}
+
 	public static native String toString(int errno);
 }
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVFormatContext.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVFormatContext.java
index 24eae74..f7f1d7e 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVFormatContext.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVFormatContext.java
@@ -38,7 +38,6 @@ public class AVFormatContext extends AVOptions {
 
 	// hmm?
 	//public native void setOutputFormat(AVOutputFormat val);
-
 	public native AVIOContext getIOContext();
 
 	public native void setIOContext(AVIOContext val);
@@ -132,7 +131,7 @@ public class AVFormatContext extends AVOptions {
 	// returns false on end of file
 	public native boolean readFrame(AVPacket pkt) throws AVIOException;
 
-		public native void seekFrame(int stream_index, long timestamp, int flags) throws AVIOException;
+	public native void seekFrame(int stream_index, long timestamp, int flags) throws AVIOException;
 
 	public native void seekFile(int stream_index, long min_ts, long ts, long max_ts, int flags) throws AVIOException;
 
@@ -153,6 +152,14 @@ public class AVFormatContext extends AVOptions {
 	// returns true if flushed
 	public native boolean writeFrame(AVPacket pktkt) throws AVIOException;
 
+	/**
+	 * Write a frame to the output.
+	 * <p>
+	 * Calls av_interleaved_write_frame().
+	 *
+	 * @param pkt Packet containing data.
+	 * @throws AVIOException on error.
+	 */
 	public native void interleavedWriteFrame(AVPacket pkt) throws AVIOException;
 
 	public native void writeUncodedFrame(int stream_index, AVFrame frame) throws AVIOException;
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVIOContext.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVIOContext.java
index 3b0c499..ea1f893 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVIOContext.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVIOContext.java
@@ -23,39 +23,25 @@ import java.nio.ByteBuffer;
 /**
  *
  */
-public class AVIOContext extends AVOptions {
+public class AVIOContext extends AVOptions implements AVIOContextBits {
+
+	/**
+	 * Maintains references required for callbacks.
+	 * <p>
+	 * This is a {@link au.notzed.nativez.ReferenceZ} object.
+	 */
+	Object opaque;
 
-	// TODO: autogen?
-	public static final int AVSEEK_SIZE = 0x10000;
-	public static final int AVSEEK_FORCE = 0x20000;
 	//
 	public static final int AVSEEK_SET = 0;
 	public static final int AVSEEK_CUR = 1;
 	public static final int AVSEEK_END = 2;
-	//
-	public static final int ALLOC_WRITE = 1;
-	public static final int ALLOC_STREAMED = 2;
-	// flags for open
-	public static final int AVIO_FLAG_READ = 1;
-	public static final int AVIO_FLAG_WRITE = 2;
-	public static final int AVIO_FLAG_READ_WRITE = 3;
-	// flags for alloc seekable
-	/**
-	 * Seeking works like for a local file.
-	 */
-	public static final int AVIO_SEEKABLE_NORMAL = (1 << 0);
-
 	/**
-	 * Seeking by timestamp with avio_seek_time() is possible.
-	 */
-	public static final int AVIO_SEEKABLE_TIME = (1 << 1);
-	/**
-	 * pseudo-flag for alloc() which sets writable to avio_context_create.
+	 * If set then alloc() will pass write_flag=1 to avio_alloc_context().
 	 */
 	public static final int AVIO_WRITABLE = (1 << 31);
 	/**
-	 * pseudo-flaga for alloc() which sets the direct indicator on the
-	 * created context.
+	 * If set, then alloc() will set AVIOContext.direct=1.
 	 */
 	public static final int AVIO_DIRECT = (1 << 30);
 
@@ -65,27 +51,58 @@ public class AVIOContext extends AVOptions {
 
 	private static native void release(long p);
 
-	//?public native int getSeekable();
 	/**
-	 * Calls avio_open.
+	 * Create an AVIOContext backed by libavformat i/o.
 	 * <p>
-	 * TODO: should it call avio_open2?
+	 * Calls avio_open2().
 	 *
 	 * @param url
 	 * @param avio_flags AVIO_FLAGS_*.
+	 * @param interrupt_cb If non-null, supplies interrupt-check function.
+	 * @param options
+	 * @return
+	 * @throws au.notzed.jjmpeg.AVIOException
+	 */
+	public static native AVIOContext open(String url, int avio_flags, AVIOInterrupt interrupt_cb, AVDictionary options) throws AVIOException;
+
+	/**
+	 * Create an AVIOContext backed by libavformat i/o with no callback or options.
+	 *
+	 * @param url
+	 * @param avio_flags
 	 * @return
+	 * @throws AVIOException
 	 */
-	public static native AVIOContext open(String url, int avio_flags) throws AVIOException;
+	public static AVIOContext open(String url, int avio_flags) throws AVIOException {
+		return open(url, avio_flags, null, null);
+	}
 
 	/**
+	 * Create an AVIOContext backed by Java I/O.
 	 *
 	 * @param buffer_size
 	 * @param alloc_flags combination of AVIO_SEEKABLE_*, AVIO_WRITABLE, and AVIO_DIRECT.
-	 * @param handler
+	 * @param handler Functions which implement i/o.
 	 * @return
 	 */
 	public static native AVIOContext alloc(int buffer_size, int alloc_flags, AVIOHandler handler);
 
+	/**
+	 * Callback hook for interrupt checking.
+	 */
+	public interface AVIOInterrupt {
+
+		/**
+		 * Called during blocking operations.
+		 *
+		 * @return true if the blocking i/o should abort.
+		 */
+		public boolean isInterrupted();
+	}
+
+	/**
+	 * Callback hooks which allow Java I/O functions to provide I/O for FFmpeg.
+	 */
 	public interface AVIOHandler {
 
 		/**
@@ -104,6 +121,13 @@ public class AVIOContext extends AVOptions {
 		 */
 		public int writePacket(ByteBuffer src);
 
+		/**
+		 * Called to perform seek.
+		 *
+		 * @param offset
+		 * @param whence AVSEEK_* value.
+		 * @return
+		 */
 		public long seek(long offset, int whence);
 	}
 }
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVIOException.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVIOException.java
index d31bb2e..e753419 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVIOException.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVIOException.java
@@ -21,7 +21,9 @@ package au.notzed.jjmpeg;
 import java.io.IOException;
 
 /**
- *
+ * General exception for FFmpeg errors.
+ * <p>
+ * This contains the error code which triggered the exception.
  */
 public class AVIOException extends IOException {
 
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVMediaType.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVMediaType.java
index 9c88e45..0e32eba 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVMediaType.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVMediaType.java
@@ -23,6 +23,10 @@ package au.notzed.jjmpeg;
  */
 public class AVMediaType implements AVMediaTypeBits {
 
+	static {
+		AVObject.init();
+	}
+
 	/**
 	 * Call av_get_media_type_string()
 	 */
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVObject.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVObject.java
index 63ff264..0bb6d50 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVObject.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVObject.java
@@ -41,7 +41,17 @@ public abstract class AVObject extends NativeZ {
 
 		AVUtil.setLogger(AVUtil.createAVLogger(Logger.getLogger("notzed.jjmpeg")));
 	}
-	
+
+	/**
+	 * Initialise AVObject.
+	 * <p>
+	 * This function does nothing itself but ensures the native library is
+	 * loaded and can be used by objects which DO NOT derive from AVObject
+	 * but need to use native calls.
+	 */
+	public static void init() {
+	}
+
 	/**
 	 * Handy iterator for various uses in the library.
 	 */
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVPacket.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVPacket.java
index b218a38..50ff939 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVPacket.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVPacket.java
@@ -45,7 +45,7 @@ public class AVPacket extends AVObject implements Cloneable {
 	 * Flag is used to discard packets which are required to maintain valid
 	 * decoder state but are not required for output and should be dropped
 	 * after decoding.
-	 *
+	 * <p>
 	 */
 	public static final int AV_PKT_FLAG_DISCARD = 0x0004;
 	/**
@@ -74,14 +74,23 @@ public class AVPacket extends AVObject implements Cloneable {
 	/**
 	 * Retrieve the current data buffer pointer and size.
 	 * <p>
-	 * This value should not be saved between calls which might update the packet.
-	 * <p>
-	 * TODO: do i even need this?
+	 * This value must not be saved between calls which might update the packet.
 	 *
 	 * @return
 	 */
 	public native ByteBuffer getData();
 
+	/**
+	 * Resize then retrieve the current data buffer pointer and size.
+	 * <p>
+	 * This will call av_packet_grow() or av_packet_shrink() as necessary
+	 * to set the data size, and will return a reference to it.
+	 *
+	 * @param size
+	 * @return
+	 */
+	public native ByteBuffer getData(long size);
+
 	/**
 	 * Clear and free any data pointers and returns the packet to an initialised state.
 	 * <p>
@@ -105,6 +114,10 @@ public class AVPacket extends AVObject implements Cloneable {
 
 	public native void setDTS(long val);
 
+	public native long getDuration();
+
+	public native void setDuration(long val);
+
 	public native int getSize();
 
 	public native int getStreamIndex();
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVPixelFormat.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVPixelFormat.java
index 65166dc..8c578ce 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVPixelFormat.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVPixelFormat.java
@@ -22,6 +22,10 @@ package au.notzed.jjmpeg;
  */
 public class AVPixelFormat implements AVPixelFormatBits {
 
+	static {
+		AVObject.init();
+	}
+
 	/**
 	 * Call av_get_pix_fmt(name)
 	 */
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVRational.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVRational.java
index 0dcac36..7dd1674 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVRational.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVRational.java
@@ -35,6 +35,10 @@ public class AVRational extends Number implements Comparable<AVRational> {
 		this.den = den;
 	}
 
+	static {
+		AVObject.init();
+	}
+
 	/**
 	 * Calls av_d2q
 	 *
@@ -112,7 +116,7 @@ public class AVRational extends Number implements Comparable<AVRational> {
 	 * Compare two rationals.
 	 *
 	 * @param b Second rational
-	 * 
+	 *
 	 * Taken from avutil/rational.c
 	 *
 	 * @return One of the following values:
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVSampleFormat.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVSampleFormat.java
index c5bd2e8..5210857 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVSampleFormat.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVSampleFormat.java
@@ -22,15 +22,17 @@ package au.notzed.jjmpeg;
  */
 public class AVSampleFormat implements AVSampleFormatBits {
 
+	static {
+		AVObject.init();
+	}
+
 	/**
 	 * Call av_get_sample_fmt(name)
 	 */
-
 	public static native int valueOf(String name);
-	
+
 	/**
 	 * Call av_get_sample_fmt_name(value)
 	 */
 	public static native String toString(int value);
 }
-
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVUtil.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVUtil.java
index 5a42751..dce3c7d 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVUtil.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/AVUtil.java
@@ -29,6 +29,10 @@ import java.util.logging.Logger;
  */
 public class AVUtil {
 
+	static {
+		AVObject.init();
+	}
+
 	/**
 	 * Call av_log_set_callback() with the provided logger.
 	 *
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/io/JJMediaReader.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/io/JJMediaReader.java
index e891247..16aa7c5 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/io/JJMediaReader.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/io/JJMediaReader.java
@@ -443,6 +443,15 @@ public class JJMediaReader implements AutoCloseable {
 			return duration;
 		}
 
+		/**
+		 * Retrieve stream start time in milliseconds.
+		 *
+		 * @return
+		 */
+		public long getStartMS() {
+			return startms;
+		}
+
 		public boolean isOpened() {
 			return opened;
 		}
diff --git a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/io/JJMediaWriter.java b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/io/JJMediaWriter.java
index 66acaec..aff403c 100644
--- a/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/io/JJMediaWriter.java
+++ b/src/notzed.jjmpeg/classes/au/notzed/jjmpeg/io/JJMediaWriter.java
@@ -27,6 +27,7 @@
  */
 package au.notzed.jjmpeg.io;
 
+import au.notzed.jjmpeg.AVChannelLayout;
 import au.notzed.jjmpeg.AVCodec;
 import au.notzed.jjmpeg.AVCodecContext;
 import au.notzed.jjmpeg.AVFormatContext;
@@ -35,7 +36,6 @@ import au.notzed.jjmpeg.AVOutputFormat;
 import au.notzed.jjmpeg.AVPacket;
 import au.notzed.jjmpeg.AVRational;
 import au.notzed.jjmpeg.AVStream;
-import au.notzed.jjmpeg.AVCodecID;
 import au.notzed.jjmpeg.AVError;
 import au.notzed.jjmpeg.AVIOContext;
 import au.notzed.jjmpeg.AVPixelFormat;
@@ -47,16 +47,18 @@ import java.util.List;
 import java.util.logging.Logger;
 
 /**
- * High level av file writer interface
+ * High level av file writer interface.
  * <p>
- * @author notzed
+ * This is still work in progress and subject to change.
  */
-public class JJMediaWriter {
+public class JJMediaWriter implements AutoCloseable {
 
 	List<JJWriterStream> streams = new ArrayList<>();
 	String filename;
 	AVFormatContext oc;
 	AVIOContext output; // need to keep ref around
+	// writeTrailer must only be called if writeHeader was successful.
+	boolean writeTrailer;
 
 	/**
 	 * Create a new stream for writing to a file.
@@ -66,16 +68,11 @@ public class JJMediaWriter {
 	 * and then call close().
 	 *
 	 * @param filename
-	 * <p>
-	 * @throws AVInvalidFormatException
 	 */
 	public JJMediaWriter(String filename) throws AVIOException {
 		this.filename = filename;
 
-		/* allocate the output media context */
 		oc = AVFormatContext.allocContext(null, null, filename);
-
-		// Caller now calls addVideoStream, etc.
 	}
 
 	/**
@@ -90,177 +87,170 @@ public class JJMediaWriter {
 	/**
 	 * The stream must be opened after adding streams and before writing to them.
 	 * <p>
-	 * @throws AVInvalidFormatException
-	 * @throws AVInvalidCodecException
 	 * @throws AVIOException
 	 */
 	public void open() throws AVIOException {
 		/* now that all the parameters are set, we can open the audio and
 		 video codecs and allocate the necessary encode buffers */
-		for (JJWriterStream sd: streams) {
+		for (JJWriterStream sd : streams) {
 			sd.open();
 		}
 
 		/* open the output file, if needed */
 		//if (!(format->flags & AVFMT_NOFILE)) {
-		output = AVIOContext.open(filename, AVIOContext.AVIO_FLAG_WRITE);
+		output = AVIOContext.open(filename, AVIOContext.AVIO_FLAG_WRITE, null, null);
 		oc.setIOContext(output);
 
 		/* write the stream header, if any */
 		oc.writeHeader(null);
-	}
-
-	/**
-	 * Add a stream using the default video codec for this stream.
-	 * The streamid is the index of the stream in the streams list.
-	 * <p>
-	 * @param width
-	 * @param height
-	 * @param frame_rate
-	 * @param bit_rate
-	 * <p>
-	 * @return
-	 */
-	public JJWriterVideo addVideoStream(int width, int height, int frame_rate, long bit_rate) throws AVIOException {
-		return addVideoStream(getFormat().getVideoCodec(), streams.size(), width, height, 1, frame_rate, bit_rate);
-	}
-
-	public JJWriterVideo addVideoStream(int width, int height, int frame_rate_num, int frame_rate_den, long bit_rate) throws AVIOException {
-		return addVideoStream(getFormat().getVideoCodec(), streams.size(), width, height, frame_rate_num, frame_rate_den, bit_rate);
-	}
-
-	public JJWriterVideo addVideoStream(int codec_id, int streamid, int width, int height, int frame_rate_den, long bit_rate) throws AVIOException {
-		return addVideoStream(codec_id, streamid, width, height, 1, frame_rate_den, bit_rate);
+		writeTrailer = true;
 	}
 
 	/**
 	 * Add a video stream.
 	 * <p>
-	 * @param codec_id
-	 * @param width
-	 * @param height
-	 * @param frame_rate
-	 * @param bit_rate
-	 * <p>
+	 * Creates and adds a video stream. The video stream size, pixel format, and bitrate must still be initialised.
+	 *
+	 * @param codec If null then use the format default codec. If non-null must be a video codec.
+	 * @param streamid StreamID to create, or -1 to use the next available slot.
 	 * @return
-	 * @throws AVInvalidStreamException
+	 * @throws AVIOException
 	 */
-	public JJWriterVideo addVideoStream(int codec_id, int streamid, int width, int height, int frame_rate_num, int frame_rate_den, long bit_rate) throws AVIOException {
+	public JJWriterVideo addVideoStream(AVCodec codec, int streamid) throws AVIOException {
 		AVCodecContext c;
+		JJWriterVideo vs;
 		AVStream st;
 
-		// TODO: all this crap should probably go into JJWriterVideo constructor
-		AVCodec codec = AVCodec.findEncoder(codec_id);
+		if (codec == null) {
+			codec = AVCodec.findEncoder(getFormat().getVideoCodec());
+			if (codec == null)
+				throw new AVIOException(AVError.AVERROR_STREAM_NOT_FOUND);
+		} else if (codec.getType() != AVMediaType.AVMEDIA_TYPE_VIDEO)
+			throw new AVIOException(AVError.AVERROR_STREAM_NOT_FOUND);
 
 		c = AVCodecContext.allocContext(codec);
-
 		st = oc.newStream(codec);
-		if (st == null) {
+		if (st == null)
 			throw new AVIOException(AVError.AVERROR_STREAM_NOT_FOUND);
-		}
-		st.setID(streams.size());
 
-		c.setCodecID(codec_id);
-		c.setCodecType(AVMediaType.AVMEDIA_TYPE_VIDEO);
-		/* put sample parameters */
-		c.setBitRate(bit_rate);
+		st.setID(streamid == -1 ? streams.size() : streamid);
 
-		/* resolution must be a multiple of two */
-		c.setWidth(width);
-		c.setHeight(height);
-		/* time base: this is the fundamental unit of time (in seconds) in terms
-		 of which frame timestamps are represented. for fixed-fps content,
-		 timebase should be 1/framerate and timestamp increments should be
-		 identically 1. */
-		st.setTimeBase(new AVRational(frame_rate_num, frame_rate_den));
-		c.setTimeBase(new AVRational(frame_rate_num, frame_rate_den));
-		c.setGOPSize(12);
-		/* emit one intra frame every twelve frames at most */
-
-		c.setPixelFormat(AVPixelFormat.AV_PIX_FMT_YUV420P);
-		if (codec_id == AVCodecID.AV_CODEC_ID_MPEG2VIDEO) {
-			/* just for testing, we also add B frames */
-			c.setMaxBFrames(2);
-		}
-		if (codec_id == AVCodecID.AV_CODEC_ID_MPEG1VIDEO) {
-			/* Needed to avoid using macroblocks in which some coeffs overflow.
-			 This does not happen with normal video, it just happens here as
-			 the motion of the chroma plane does not match the luma plane. */
-			c.setMBDecision(2);
-		}
-		// FIXME: some formats want stream headers to be separate
-		if ((oc.getOutputFormat().getFlags() & AVOutputFormat.AVFMT_GLOBALHEADER) != 0) {
-			c.setFlags(AVCodecContext.AV_CODEC_FLAG_GLOBAL_HEADER, AVCodecContext.AV_CODEC_FLAG_GLOBAL_HEADER);
-		}
+		c.setCodecID(codec.getID());
+		c.setCodecType(codec.getType());
 
-		Logger.getLogger("jjmpeg.io")
-			.fine(()
-				-> String.format("add avideo stream %s %d [%dx%d %s aspect %s]\n",
-				codec.getName(), c.getBitRate(),
-				c.getWidth(), c.getHeight(), AVPixelFormat.toString(c.getPixelFormat()),
-				c.getAspectRatio()));
+		if ((oc.getOutputFormat().getFlags() & AVOutputFormat.AVFMT_GLOBALHEADER) != 0)
+			c.setFlags(AVCodecContext.AV_CODEC_FLAG_GLOBAL_HEADER, AVCodecContext.AV_CODEC_FLAG_GLOBAL_HEADER);
 
-		JJWriterVideo sd = new JJWriterVideo(st, c);
-		streams.add(sd);
+		vs = new JJWriterVideo(st, c);
+		streams.add(vs);
 
-		return sd;
+		return vs;
 	}
 
 	/**
-	 * Add a new audio stream.
+	 * Add an initialise a video stream.
 	 * <p>
-	 * @param codec_id
-	 * @param streamid
-	 * @param fmt
-	 * @param sample_rate
-	 * @param bit_rate
+	 * The supplied parameters are used to initialise the corresponding fields of the AVCodecContext. Other fields initialised
+	 * are:
+	 * <ul>
+	 * <li>AVCodecContext.TimeBase=1 / frame_rate
+	 * <li>AVStream.TimeBase=1 / frame_rate
+	 * </ul>
+	 *
+	 * @param codec If null then use the format default codec. If non-null must be a video codec.
+	 * @param streamid StreamID to create, or -1 to use the next available slot.
+	 * @param pixel_format AVPixelFormat.
+	 * @param width Width of video stream.
+	 * @param height Height of video stream.
+	 * @param frame_rate Display frame rate. It's inverse is also set as the stream and codec timebase.
+	 * @param bit_rate Bitrate of encoding.
 	 * <p>
 	 * @return
-	 * @throws AVInvalidStreamException
+	 * @throws au.notzed.jjmpeg.AVIOException on error
 	 */
-	public JJWriterAudio addAudioStream(int codec_id, int streamid, int fmt, int sample_rate, int channels, long bit_rate) throws AVIOException {
+	public JJWriterVideo addVideoStream(AVCodec codec, int streamid, int pixel_format, int width, int height, AVRational frame_rate, long bit_rate) throws AVIOException {
+		JJWriterVideo sd = addVideoStream(codec, streamid);
+
+		/* Initialise provided parameters */
+		AVCodecContext c = sd.c;
+		AVStream st = sd.stream;
+
+		c.setWidth(width);
+		c.setHeight(height);
+
+		st.setAverageFrameRate(frame_rate);
+		sd.setTimeBase(new AVRational(frame_rate.den, frame_rate.num));
+
+		c.setBitRate(bit_rate);
+		c.setPixelFormat(pixel_format);
+
+		return sd;
+	}
+
+	public JJWriterAudio addAudioStream(AVCodec codec, int streamid) throws AVIOException {
 		AVCodecContext c;
+		JJWriterAudio as;
 		AVStream st;
 
-		AVCodec codec = AVCodec.findEncoder(codec_id);
+		if (codec == null) {
+			codec = AVCodec.findEncoder(getFormat().getAudioCodec());
+			if (codec == null)
+				throw new AVIOException(AVError.AVERROR_STREAM_NOT_FOUND);
+		} else if (codec.getType() != AVMediaType.AVMEDIA_TYPE_AUDIO)
+			throw new AVIOException(AVError.AVERROR_STREAM_NOT_FOUND);
 
 		c = AVCodecContext.allocContext(codec);
-
 		st = oc.newStream(codec);
-		if (st == null) {
+		if (st == null)
 			throw new AVIOException(AVError.AVERROR_STREAM_NOT_FOUND);
-		}
-
-		c.setCodecID(codec_id);
-		c.setCodecType(AVMediaType.AVMEDIA_TYPE_AUDIO);
 
-		c.setSampleFormat(fmt);
-		c.setBitRate(bit_rate);
-		c.setSampleRate(sample_rate);
+		st.setID(streamid == -1 ? streams.size() : streamid);
 
-		c.setNumChannels(channels);
-		c.setChannelLayout(4);
+		c.setCodecID(codec.getID());
+		c.setCodecType(codec.getType());
 
-		if ((oc.getOutputFormat().getFlags() & AVOutputFormat.AVFMT_GLOBALHEADER) != 0) {
+		if ((oc.getOutputFormat().getFlags() & AVOutputFormat.AVFMT_GLOBALHEADER) != 0)
 			c.setFlags(AVCodecContext.AV_CODEC_FLAG_GLOBAL_HEADER, AVCodecContext.AV_CODEC_FLAG_GLOBAL_HEADER);
-		}
 
-		Logger.getLogger("jjmpeg.io")
-			.fine(()
-				-> String.format("add audio stream audio %s %d [x%d %dHz %s]\n",
-				codec.getName(), c.getBitRate(),
-				c.getNumChannels(), c.getSampleRate(), AVSampleFormat.toString(c.getSampleFormat())));
+		as = new JJWriterAudio(st, c);
+		streams.add(as);
 
-		JJWriterAudio as = new JJWriterAudio(st, c);
+		return as;
+	}
 
-		streams.add(as);
+	/**
+	 * Add an initialise an audio stream.
+	 * <p>
+	 * @param codec If null then use the format default codec. If non-null must be a video codec.
+	 * @param streamid StreamID to create, or -1 to use the next available slot.
+	 * @param sample_format AVSampleFormat
+	 * @param sample_rate Cycles per second.
+	 * @param layout AVChannelLayout
+	 * @param bit_rate Encoding bit rate.
+	 * <p>
+	 * @return
+	 * @throws au.notzed.jjmpeg.AVIOException
+	 * @see AVSampleFormat
+	 * @see AVChannelLayout
+	 * @see AVChannelLayout#getDefaultLayout(int)
+	 */
+	public JJWriterAudio addAudioStream(AVCodec codec, int streamid, int sample_format, int sample_rate, long layout, long bit_rate) throws AVIOException {
+		JJWriterAudio as = addAudioStream(codec, streamid);
+		AVCodecContext c = as.c;
+
+		c.setSampleFormat(sample_format);
+		c.setBitRate(bit_rate);
+		c.setSampleRate(sample_rate);
+
+		c.setNumChannels(AVChannelLayout.getNumChannels(layout));
+		c.setChannelLayout(layout);
 
 		return as;
 	}
 
 	public void flush() throws AVIOException {
-		for (JJWriterStream sd: streams) {
-			sd.addFrame(null);
+		for (JJWriterStream sd : streams) {
+			sd.writeFrame(null);
 		}
 	}
 
@@ -270,19 +260,17 @@ public class JJMediaWriter {
 	public void close() throws AVIOException {
 
 		flush();
-		/* write the trailer, if any.  the trailer must be written
-		 * before you close the CodecContexts open when you wrote the
-		 * header; otherwise write_trailer may try to use memory that
-		 * was freed on av_codec_close() */
-		oc.writeTrailer();
-
-		/* close each codec */
-		for (JJWriterStream sd: streams) {
-			sd.close();
+		if (writeTrailer) {
+			/* write the trailer, if any.  the trailer must be written
+			* before you close the CodecContexts open when you wrote the
+			* header; otherwise write_trailer may try to use memory that
+			* was freed on av_codec_close() */
+			oc.writeTrailer();
 		}
 
-		/* close the output file */
-		//output.close();
+		for (JJWriterStream sd : streams) {
+			sd.close();
+		}
 
 		/* free the stream */
 		oc.release();
@@ -322,6 +310,21 @@ public class JJMediaWriter {
 			return c;
 		}
 
+		public void setTimeBase(AVRational timeBase) {
+			stream.setTimeBase(timeBase);
+			c.setTimeBase(timeBase);
+		}
+
+		public void setBitRate(long bit_rate) {
+			c.setBitRate(bit_rate);
+		}
+
+		/**
+		 * Open a write stream.
+		 * This performs the step of set
+		 *
+		 * @throws AVIOException
+		 */
 		public void open() throws AVIOException {
 			AVCodec codec = AVCodec.findEncoder(c.getCodecID());
 
@@ -332,12 +335,38 @@ public class JJMediaWriter {
 			opened = true;
 		}
 
-		public void addFrame(AVFrame frame) throws AVIOException {
+		/**
+		 * Write encoded packet.
+		 * If the data is already in the correct format then use this to
+		 * add a packet to the stream.
+		 * <p>
+		 * This sets the packet streamIndex and rescales the timestamp and calls
+		 * {@link AVFormatContext#interleavedWriteFrame(au.notzed.jjmpeg.AVPacket)}
+		 *
+		 * @param packet
+		 * @throws AVIOException
+		 */
+		public void writePacket(AVPacket packet) throws AVIOException {
+			packet.rescaleTS(c.getTimeBase(), stream.getTimeBase());
+			packet.setStreamIndex(stream.getIndex());
+			oc.interleavedWriteFrame(packet);
+		}
+
+		/**
+		 * Write unencoded frame.
+		 * <p>
+		 * The frame is passed through the
+		 * {@link AVCodecContext#sendFrame(au.notzed.jjmpeg.AVFrame) /
+		 * {@link AVCodecContext#receivePacket(au.notzed.jjmpeg.AVPacket)
+		 * sequence and then written to the output.
+		 *
+		 * @param frame
+		 * @throws AVIOException on error.
+		 */
+		public void writeFrame(AVFrame frame) throws AVIOException {
 			if (c.sendFrame(frame)) {
 				while (c.receivePacket(packet)) {
-					packet.rescaleTS(c.getTimeBase(), stream.getTimeBase());
-					packet.setStreamIndex(stream.getIndex());
-					oc.interleavedWriteFrame(packet);
+					writePacket(packet);
 				}
 			}
 		}
@@ -364,6 +393,30 @@ public class JJMediaWriter {
 			super.open();
 
 			frame = AVFrame.alloc(c.getPixelFormat(), c.getWidth(), c.getHeight());
+
+			Logger.getLogger("jjmpeg.io")
+				.fine(()
+					-> String.format("open video stream %s %d [%dx%d %s aspect %s]\n",
+					AVCodec.findEncoder(c.getCodecID()).getName(),
+					c.getBitRate(),
+					c.getWidth(), c.getHeight(), AVPixelFormat.toString(c.getPixelFormat()),
+					c.getAspectRatio()));
+		}
+
+		public void setWidth(int width) {
+			c.setWidth(width);
+		}
+
+		public void setHeight(int height) {
+			c.setHeight(height);
+		}
+
+		public void setPixelFormat(int format) {
+			c.setPixelFormat(format);
+		}
+
+		public void setAverateFrameRate(AVRational frameRate) {
+			stream.setAverageFrameRate(frameRate);
 		}
 
 		@Override
@@ -382,13 +435,13 @@ public class JJMediaWriter {
 		 * <p>
 		 * @param frame Video frame to write, or null to flush buffers.
 		 * <p>
-		 * @throws AVEncodingError
-		 * @throws AVIOException
+		 * @throws AVIOException on error.
 		 */
-		public void addFrame(AVFrame frame) throws AVIOException {
-			if (frame != null)
-				frame.setPTS(nextPTS++);
-			super.addFrame(frame);
+		@Override
+		public void writeFrame(AVFrame frame) throws AVIOException {
+			//if (frame != null)
+			//	frame.setPTS(nextPTS++);
+			super.writeFrame(frame);
 		}
 
 	}
@@ -399,6 +452,22 @@ public class JJMediaWriter {
 			super(stream, c);
 		}
 
+		public void setSampleFormat(int sample_format) {
+			c.setSampleFormat(sample_format);
+		}
+
+		public void setSampleRate(int sample_rate) {
+			c.setSampleRate(sample_rate);
+		}
+
+		public void setNumChannels(int channels) {
+			c.setNumChannels(channels);
+		}
+
+		public void setChannelLayout(long layout) {
+			c.setChannelLayout(layout);
+		}
+
 		@Override
 		public void open() throws AVIOException {
 			super.open();
@@ -409,6 +478,13 @@ public class JJMediaWriter {
 
 			// ??? unchecked
 			frame = AVFrame.alloc(c.getSampleFormat(), c.getNumChannels(), 2048);
+
+			Logger.getLogger("jjmpeg.io")
+				.fine(()
+					-> String.format("open audio stream %s %d [x%d %dHz %s]\n",
+					AVCodec.findEncoder(c.getCodecID()).getName(),
+					c.getBitRate(),
+					c.getNumChannels(), c.getSampleRate(), AVSampleFormat.toString(c.getSampleFormat())));
 		}
 
 		@Override
diff --git a/src/notzed.jjmpeg/gen/extract-defines.pl b/src/notzed.jjmpeg/gen/extract-defines.pl
index cd82b46..cddf729 100644
--- a/src/notzed.jjmpeg/gen/extract-defines.pl
+++ b/src/notzed.jjmpeg/gen/extract-defines.pl
@@ -175,11 +175,13 @@ sub scan {
 	    my $def = $1;
 	    #print $1."\n";
 	    if ($lastc ne "") {
-		#$lastc =~ s@\t+@\t@g;
+		$lastc =~ s@\"@\\\"@g;
 		print C "\tprintf(\"%s\", \"$lastc\");\n";	    
 	    } elsif (m@///< (.*)@ || m@/\*\|<(.*)\*@) {
+		my $com = $1;
+		$com =~ s@\"@\\\"@g;
 		# handle single-line comments, perhaps these should override
-		print C "\tprintf(\"\\t/**\\n\\t * $1\\n\\t */\\n\");\n";
+		print C "\tprintf(\"\\t/**\\n\\t * $com\\n\\t */\\n\");\n";
 	    }
 	
 	    print C "\tprintf(\"\\tpublic final static $o{type} $def = $o{cfmt};\\n\", $o{ctype}$def$o{shift});\n";
diff --git a/src/notzed.jjmpeg/gen/gen.make b/src/notzed.jjmpeg/gen/gen.make
index 9bada1d..6281db8 100644
--- a/src/notzed.jjmpeg/gen/gen.make
+++ b/src/notzed.jjmpeg/gen/gen.make
@@ -28,6 +28,7 @@ notzed.jjmpeg_JAVA_GENERATED =			\
  au/notzed/jjmpeg/AVCodecIDBits.java		\
  au/notzed/jjmpeg/AVDiscardBits.java		\
  au/notzed/jjmpeg/AVErrorBits.java		\
+ au/notzed/jjmpeg/AVIOContextBits.java		\
  au/notzed/jjmpeg/AVMediaTypeBits.java		\
  au/notzed/jjmpeg/AVOptionsBits.java		\
  au/notzed/jjmpeg/AVPixelFormatBits.java	\
@@ -87,6 +88,10 @@ $(tmp)/AVCodecBits-gen.c: $(extract_defines) $(dep)
 	@install -d $(@D)
 	perl $(extract_defines) -c -interface AVCodecBits -f $(FFMPEG_HOME) -header libavcodec/avcodec.h -d AV_CODEC_CAP_ $@
 
+$(tmp)/AVIOContextBits-gen.c: $(extract_defines) $(dep)
+	@install -d $(@D)
+	perl $(extract_defines) -c -interface AVIOContextBits -f $(FFMPEG_HOME) -header libavformat/avio.h -d AVSEEK_ -d AVIO_FLAG_ -d AVIO_SEEKABLE_ $@
+
 $(tmp)/AVOptionsBits-gen.c: $(extract_defines) $(dep)
 	@install -d $(@D)
 	perl $(extract_defines) -c -interface AVOptionsBits -f $(FFMPEG_HOME) -header libavutil/opt.h -d AV_OPT_ $@
diff --git a/src/notzed.jjmpeg/jni/jj-avcodeccontext.c b/src/notzed.jjmpeg/jni/jj-avcodeccontext.c
index 78bda20..bd8eb93 100644
--- a/src/notzed.jjmpeg/jni/jj-avcodeccontext.c
+++ b/src/notzed.jjmpeg/jni/jj-avcodeccontext.c
@@ -35,13 +35,8 @@ jint AVCodecContext_OnLoad(JavaVM *vmi, JNIEnv *env) {
 
 GS_int(AVCodecContext, CodecType, codec_type)
 GS_int(AVCodecContext, CodecID, codec_id)
-GS_int(AVCodecContext, CodecTag, codec_tag)
 GS_long(AVCodecContext, BitRate, bit_rate)
-GS_int(AVCodecContext, BitRateTolerance, bit_rate_tolerance)
 GS_int(AVCodecContext, GlobalQuality, global_quality)
-GS_int(AVCodecContext, CompressionLevel, compression_level)
-//GS_int(AVCodecContext, Flags1, flags)
-//GS_int(AVCodecContext, Flags2, flags2)
 
 JNIEXPORT jlong JNICALL MAKE_JJNAME(AVCodecContext, getFlags)
 (JNIEnv *env , jobject jo) {
@@ -77,7 +72,6 @@ JNIEXPORT void JNICALL MAKE_JJNAME(AVCodecContext, setTimeBase)
 	o->time_base = AVRational_get(env, jtb);
 }
 
-GS_int(AVCodecContext, TicksPerFrame, ticks_per_frame)
 GET_prim(jint, AVCodecContext, Delay, delay)
 
 /* Video options */
@@ -88,35 +82,17 @@ GS_int(AVCodecContext, GOPSize, gop_size)
 
 GS_int(AVCodecContext, PixelFormat, pix_fmt)
 
-GS_int(AVCodecContext, MaxBFrames, max_b_frames)
-GS_float(AVCodecContext, BQuantFactor, b_quant_factor)
-GS_float(AVCodecContext, BQuantOffset, b_quant_offset)
-
-GET_bool(AVCodecContext, hasBFrames, has_b_frames)
-
-GS_float(AVCodecContext, IQuantFactor, i_quant_factor)
-GS_float(AVCodecContext, IQuantOffset, i_quant_offset)
-
-GS_int(AVCodecContext, MBDecision, mb_decision)
-
 /* Audio options */
 GS_int(AVCodecContext, SampleRate, sample_rate)
 GS_int(AVCodecContext, NumChannels, channels)
 GS_int(AVCodecContext, SampleFormat, sample_fmt)
-GS_int(AVCodecContext, FrameSize, frame_size)
+GET_prim(jint, AVCodecContext, FrameSize, frame_size)
 GET_prim(jint, AVCodecContext, FrameNumber, frame_number)
 GS_long(AVCodecContext, ChannelLayout, channel_layout)
 GS_long(AVCodecContext, RequestChannelLayout, request_channel_layout)
-GS_int(AVCodecContext, StrictStdCompliance, strict_std_compliance)
-
-GS_int(AVCodecContext, ErrorConcealment, error_concealment)
-GS_int(AVCodecContext, ErrorRecognition, err_recognition) // !!
-
-GS_int(AVCodecContext, DCTAlgo, dct_algo)
-GS_int(AVCodecContext, IDCTAlgo, idct_algo)
 
+/* other options */
 GS_int(AVCodecContext, ThreadCount, thread_count)
-GS_int(AVCodecContext, Profile, profile)
 
 /* ********************************************************************** */
 /* Methods */
diff --git a/src/notzed.jjmpeg/jni/jj-aviocontext.c b/src/notzed.jjmpeg/jni/jj-aviocontext.c
index 2b27ac2..51725b4 100644
--- a/src/notzed.jjmpeg/jni/jj-aviocontext.c
+++ b/src/notzed.jjmpeg/jni/jj-aviocontext.c
@@ -29,27 +29,28 @@ jint AVIOContext_OnLoad(JavaVM *vmi, JNIEnv *env) {
 
 /* ********************************************************************** */
 
+/*
+ * All the callbacks use this structure to find the java instance
+ * which implement it.
+ *
+ * AVIOContext.open() has a further complication in that there is
+ * nowhere to store a pointer to this.  To get around this if an
+ * interrupt callback is supplied it is referenced in an instance of a
+ * nativez.ReferenceZ object and set on the java AVIOContext.opaque
+ * field.
+ */
 struct jj_io {
-	// AVIOHandler global reference
+	// AVIOHandler or AVIOInterrupt depending on how it was created
 	jobject jhandler;
-	// direct ByteBuffer for this data
-	// I don't think this will work looking at avio*.c
-	//jobject jbuffer;
-	//uint8_t *buffer;
 };
 
 static int jj_read_packet(void *opaque, uint8_t *buf, int buf_size) {
-	JNIEnv *env = nativez_AttachCurrentThread();
+	JNIEnv *env = nativez_AttachCurrentThreadAsDaemon();
 	
 	if (env) {
 		struct jj_io *jjio = opaque;
-		//size_t position = (buf - jjio->buffer);
 		jvalue args[1];
 
-		//jjbufferSetLimit(env, jjio->jbuffer, (int)(position + buf_size));
-		//jjbufferSetPosition(env, jjio->jbuffer, (int)(position));
-		//args[0].l = jjio->jbuffer;
-
 		args[0].l = nativez_NewDirectBuffer(env, buf, buf_size);
 
 		return (*env)->CallIntMethodA(env, jjio->jhandler, AVIOHandler_readPacket_l, args);
@@ -59,17 +60,12 @@ static int jj_read_packet(void *opaque, uint8_t *buf, int buf_size) {
 }
 
 static int jj_write_packet(void *opaque, uint8_t *buf, int buf_size) {
-	JNIEnv *env = nativez_AttachCurrentThread();
+	JNIEnv *env = nativez_AttachCurrentThreadAsDaemon();
 
 	if (env) {
 		struct jj_io *jjio = opaque;
-		//size_t position = (buf - jjio->buffer);
 		jvalue args[1];
 
-		//jjbufferSetLimit(env, jjio->jbuffer, (int)(position + buf_size));
-		//jjbufferSetPosition(env, jjio->jbuffer, (int)(position));
-		//args[0].l = jjio->jbuffer;
-
 		args[0].l = nativez_NewDirectBuffer(env, buf, buf_size);
 
 		return (*env)->CallIntMethodA(env, jjio->jhandler, AVIOHandler_writePacket_l, args);
@@ -79,7 +75,7 @@ static int jj_write_packet(void *opaque, uint8_t *buf, int buf_size) {
 }
 
 static int64_t jj_seek(void *opaque, int64_t offset, int whence) {
-	JNIEnv *env = nativez_AttachCurrentThread();
+	JNIEnv *env = nativez_AttachCurrentThreadAsDaemon();
 
 	if (env) {
 		struct jj_io *jjio = opaque;
@@ -94,6 +90,18 @@ static int64_t jj_seek(void *opaque, int64_t offset, int whence) {
 	}
 }
 
+static int jj_interrupt(void *opaque) {
+	JNIEnv *env = nativez_AttachCurrentThreadAsDaemon();
+
+	if (env) {
+		struct jj_io *jjio = opaque;
+
+		return (*env)->CallBooleanMethodA(env, jjio->jhandler, AVIOInterrupt_isInterrupted_, NULL);
+	} else {
+		return 1;
+	}
+}
+
 JNIEXPORT void JNICALL Java_au_notzed_jjmpeg_AVIOContext_release
 (JNIEnv *env, jclass jc, jlong jic) {
 	AVIOContext *ic = (void *)(uintptr_t)jic;
@@ -102,29 +110,63 @@ JNIEXPORT void JNICALL Java_au_notzed_jjmpeg_AVIOContext_release
 		struct jj_io *jjio = ic->opaque;
 
 		(*env)->DeleteGlobalRef(env, jjio->jhandler);
-		//(*env)->DeleteGlobalRef(env, jjio->jbuffer);
-		//DLCALL(av_free)(jjio->buffer);
-		free(jjio);
-		
 		DLCALL(av_free)(ic->buffer);
 		DLCALL(avio_context_free)(&ic);
+		free(jjio);
 	} else {
 		DLCALL(avio_close)(ic);
 	}
 }
 
 JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVIOContext_open
-(JNIEnv *env, jclass jc, jstring jurl, jint flags) {
-	const char *url = nativez_GetString(env, jurl);
-	AVIOContext *ic = NULL;
+(JNIEnv *env, jclass jc, jstring jurl, jint flags, jobject jcb, jobject joptions) {
+	AVIOContext *io = NULL;
 	int res;
+	struct jj_io *jjio = NULL;
+	AVIOInterruptCB cb = { 0, 0 };
+	jobject jio = NULL;
+	jobject jrefs = NULL;
+	
+	jjio = malloc(sizeof(*jjio));
+	if (!jjio) {
+		nativez_ThrowOutOfMemoryError(env, "Allocating handler");
+		return NULL;
+	}
+	
+	if (jcb) {
+		// FIXME: check returns
+		jrefs = ReferenceZ_create(env, &jcb, 1);
+		jjio->jhandler = (*env)->NewGlobalRef(env, jcb);
+		cb.callback = jj_interrupt;
+		cb.opaque = jjio;
+	}
 	
-	res = DLCALL(avio_open)(&ic, url, flags);
-	if (res < 0)
+	AVDictionary *options = AVDictionary_get(env, joptions);
+	const char *url = nativez_GetString(env, jurl);
+	
+	res = DLCALL(avio_open2)(&io, url, flags, &cb, &options);
+	AVDictionary_set(env, joptions, options, 1);
+
+	if (res < 0) {
 		jjthrowAVIOException(env, res, url);
+		goto fail;
+	}
+
+	jio = NativeZ_create(env, jc, io);
+	if (!jio)
+		goto fail;
+
+	
+	(*env)->SetObjectField(env, jio, AVIOContext_opaque, jrefs);
+
+	return jio;
+ fail:
 	nativez_ReleaseString(env, jurl, url);
+	if (jjio->jhandler)
+		(*env)->DeleteGlobalRef(env, jjio->jhandler);
+	free(jjio);
 
-	return NativeZ_create(env, jc, ic);
+	return NULL;
 }
 
 JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVIOContext_alloc
@@ -132,35 +174,40 @@ JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVIOContext_alloc
 	AVIOContext *io = NULL;
 	struct jj_io *jjio;
 	uint8_t *buffer;
+	jobject jio = NULL;
 
 	jjio = malloc(sizeof(*jjio));
-	if (jjio) {
-		buffer = DLCALL(av_malloc)(buffer_size);
-		if (buffer) {
-			int write_flag = (jflags & au_notzed_jjmpeg_AVIOContext_AVIO_WRITABLE) != 0;
+	if (!jjio)
+		goto fail_nojjio;
 
-			jjio->jhandler = (*env)->NewGlobalRef(env, jhandler);
-			//jjio->jbuffer = jjnewDirectBuffer(env, jjio->buffer, buffer_size);
+	buffer = DLCALL(av_malloc)(buffer_size);
+	if (!buffer)
+		goto fail_nobuffer;
+	
+	jjio->jhandler = (*env)->NewGlobalRef(env, jhandler);
 		
-			io = DLCALL(avio_alloc_context)(buffer, buffer_size, write_flag, jjio,
-						      jj_read_packet,
-						      jj_write_packet,
-						      jj_seek);
-			if (io) {
-				io->seekable = jflags & 3;
-				io->direct = (jflags & au_notzed_jjmpeg_AVIOContext_AVIO_DIRECT) != 0;
-			} else {
-				nativez_ThrowOutOfMemoryError(env, "Allocating io context");
-				free(buffer);
-				free(jjio);
-			}
-		} else {
-			nativez_ThrowOutOfMemoryError(env, "Allocating buffer");
-			free(jjio);
-		}
-	} else {
-		nativez_ThrowOutOfMemoryError(env, "Allocating handler");
-	}
-
-	return NativeZ_create(env, jc, io);
+	io = DLCALL(avio_alloc_context)(buffer, buffer_size,
+					(jflags & au_notzed_jjmpeg_AVIOContext_AVIO_WRITABLE) != 0,
+					jjio,
+					jj_read_packet,
+					jj_write_packet,
+					jj_seek);
+	if (!io)
+		goto fail;
+
+	io->seekable = jflags & (AVIO_SEEKABLE_NORMAL | AVIO_SEEKABLE_TIME);
+	io->direct = (jflags & au_notzed_jjmpeg_AVIOContext_AVIO_DIRECT) != 0;
+	jio = NativeZ_create(env, jc, io);
+	if (!jio)
+		goto fail;
+
+	return jio;
+ fail:
+	(*env)->DeleteGlobalRef(env, jjio->jhandler);
+	free(buffer);
+ fail_nobuffer:
+	free(jjio);
+ fail_nojjio:
+	nativez_ThrowOutOfMemoryError(env, "Allocating io context");
+	return NULL;
 }
diff --git a/src/notzed.jjmpeg/jni/jj-aviocontext.def b/src/notzed.jjmpeg/jni/jj-aviocontext.def
index f1a2fe7..fec52b1 100644
--- a/src/notzed.jjmpeg/jni/jj-aviocontext.def
+++ b/src/notzed.jjmpeg/jni/jj-aviocontext.def
@@ -3,7 +3,7 @@ header avformat libavformat/avio.h {
 	avio_alloc_context
 	avio_context_free
 
-	avio_open
+	avio_open2
 	avio_close
 }
 
@@ -12,6 +12,14 @@ header avutil libavutil/mem.h {
 	av_free
 }
 
+java AVIOContext au/notzed/jjmpeg/AVIOContext {
+     opaque, Ljava/lang/Object;
+}
+
+java AVIOInterrupt au/notzed/jjmpeg/AVIOContext$AVIOInterrupt {
+     isInterrupted, ()Z
+}
+
 java AVIOHandler au/notzed/jjmpeg/AVIOContext$AVIOHandler {
      readPacket, (Ljava/nio/ByteBuffer;)I
      writePacket, (Ljava/nio/ByteBuffer;)I
diff --git a/src/notzed.jjmpeg/jni/jj-avpacket.c b/src/notzed.jjmpeg/jni/jj-avpacket.c
index bd57fa4..fe2f3e1 100644
--- a/src/notzed.jjmpeg/jni/jj-avpacket.c
+++ b/src/notzed.jjmpeg/jni/jj-avpacket.c
@@ -34,6 +34,7 @@ jint AVPacket_OnLoad(JavaVM *vmi, JNIEnv *env) {
 
 GS_long(AVPacket, PTS, pts)
 GS_long(AVPacket, DTS, dts)
+GS_long(AVPacket, Duration, duration)
 GET_prim(jint, AVPacket, Size, size)
 GS_int(AVPacket, StreamIndex, stream_index)
 GET_prim(jint, AVPacket, Flags, flags)
@@ -61,14 +62,16 @@ JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVPacket_alloc
 (JNIEnv *env, jclass jc) {
 	AVPacket *packet = DLCALL(av_packet_alloc)();
 
-	//if (!packet) // outofmemoryerror?
-
-	return NativeZ_create(env, jc, packet);
+	if (nativez_NonNull(env, "Allocating AVPacket", packet)) {
+		DLCALL(av_init_packet)(packet);
+		return NativeZ_create(env, jc, packet);
+	}
+	return NULL;
 }
 
 /* **************************************** */
 
-JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVPacket_getData
+JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVPacket_getData__
 (JNIEnv *env, jobject jpacket) {
 	AVPacket *packet = NativeZ_getP(env, jpacket);
 
@@ -78,6 +81,25 @@ JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVPacket_getData
 	return NULL;
 }
 
+JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVPacket_getData__J
+(JNIEnv *env, jobject jpacket, jlong size) {
+	AVPacket *packet = NativeZ_getP(env, jpacket);
+
+	if (packet->size < size) {
+		if (av_grow_packet(packet, size - packet->size) != 0) {
+			nativez_ThrowOutOfMemoryError(env, "Unable to grow packet");
+			return NULL;
+		}
+	} else {
+		av_shrink_packet(packet, size);
+	}
+	
+	if (nativez_NonNull(env, "No data pointer", packet->data))
+		return nativez_NewDirectBuffer(env, packet->data, packet->size);
+
+	return NULL;
+}
+
 JNIEXPORT void JNICALL Java_au_notzed_jjmpeg_AVPacket_clear
 (JNIEnv *env, jobject jpacket) {
 	AVPacket *packet = NativeZ_getP(env, jpacket);
@@ -90,8 +112,9 @@ JNIEXPORT jobject JNICALL Java_au_notzed_jjmpeg_AVPacket_clone
 	AVPacket *packet = NativeZ_getP(env, jpacket);
 	AVPacket *dst = DLCALL(av_packet_clone)(packet);
 
-	// if !dst ...
-	return NativeZ_create(env, AVPacket_classid, dst);	
+	if (nativez_NonNull(env, "Cloning AVPacket", dst))
+		return NativeZ_create(env, AVPacket_classid, dst);
+	return NULL;
 }
 
 JNIEXPORT void JNICALL Java_au_notzed_jjmpeg_AVPacket_rescaleTS
diff --git a/src/notzed.jjmpeg/jni/jj-avpacket.def b/src/notzed.jjmpeg/jni/jj-avpacket.def
index 3352b5a..92c42ae 100644
--- a/src/notzed.jjmpeg/jni/jj-avpacket.def
+++ b/src/notzed.jjmpeg/jni/jj-avpacket.def
@@ -4,6 +4,8 @@ header avcodec libavcodec/avcodec.h {
 	av_packet_unref
 	av_packet_clone
 	av_packet_rescale_ts
+
+	av_init_packet
 }
 
 java AVPacket au/notzed/jjmpeg/AVPacket {
diff --git a/src/notzed.jjmpeg/jni/jj-avutil.c b/src/notzed.jjmpeg/jni/jj-avutil.c
index a8d4bb7..8de4a15 100644
--- a/src/notzed.jjmpeg/jni/jj-avutil.c
+++ b/src/notzed.jjmpeg/jni/jj-avutil.c
@@ -30,7 +30,7 @@ jint AVUtil_OnLoad(JavaVM *vmi, JNIEnv *env) {
 static jobject jlogger_ref;
 
 static void log_callback(void*ptr, int level, const char*fmt, va_list vl) {
-	JNIEnv *env = nativez_AttachCurrentThread();
+	JNIEnv *env = nativez_AttachCurrentThreadAsDaemon();
 
 	if (env) {
 		char log[1024];
diff --git a/src/notzed.jjmpeg/jni/jjmpeg-jni.c b/src/notzed.jjmpeg/jni/jjmpeg-jni.c
index a59381c..3c9a433 100644
--- a/src/notzed.jjmpeg/jni/jjmpeg-jni.c
+++ b/src/notzed.jjmpeg/jni/jjmpeg-jni.c
@@ -83,7 +83,7 @@ void jjthrowAVIOException(JNIEnv *env, int error, const char *msg) {
 
 /* ********************************************************************** */
 
-jstring jjnewIntArrayT(JNIEnv *env, const int *ap, int terminal) {
+jintArray jjnewIntArrayT(JNIEnv *env, const int *ap, int terminal) {
 	jintArray ret = NULL;
 
 	if (ap) {
@@ -94,6 +94,7 @@ jstring jjnewIntArrayT(JNIEnv *env, const int *ap, int terminal) {
 		ret = (*env)->NewIntArray(env, len);
 		(*env)->SetIntArrayRegion(env, ret, 0, len, (const jint *)ap);
 	}
+
 	return ret;
 }
 
diff --git a/src/notzed.jjmpeg/jni/jjmpeg.h b/src/notzed.jjmpeg/jni/jjmpeg.h
index d29f641..be1aa4c 100644
--- a/src/notzed.jjmpeg/jni/jjmpeg.h
+++ b/src/notzed.jjmpeg/jni/jjmpeg.h
@@ -161,7 +161,7 @@
  * @param ap Array pointer, may be NULL.
  * @param terminal Terminating value.
  */
-jstring jjnewIntArrayT(JNIEnv *env, const int *ap, int terminal);
+jintArray jjnewIntArrayT(JNIEnv *env, const int *ap, int terminal);
 
 void jjthrowAVIOException(JNIEnv *env, int error, const char *msg);