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fix: wait for a decoder input buffer instead of dropping NAL units after 5 ms (#89) #106

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Merged
compot-dev merged 3 commits into from
Oct 13, 2026
Merged

fix: wait for a decoder input buffer instead of dropping NAL units after 5 ms (#89) #106

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8295373
fix: wait up to 40 ms for a decoder input buffer, giving frames back …
compot-dev Oct 13, 2026
a99918a
fix: the input wait gives way to a close or pause waiting for the dec…
compot-dev Oct 13, 2026
14b3dec
fix: a wait cut short by a close or pause is not counted as a decoder…
compot-dev Oct 13, 2026
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81 changes: 58 additions & 23 deletions android/app/src/main/java/com/openipc/decoder/MediaCodecManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
import java.nio.ByteBuffer;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;

class MediaCodecManager {
private static final String TAG = "OpenIPCDecoder";
Expand All @@ -30,6 +31,14 @@ class MediaCodecManager {

/** Largest NAL unit (single view); 4K key frames at high bitrate can exceed 1 MiB. */
static final int MAX_NAL_SIZE = 2 * 1024 * 1024;
/** One wait for a free input buffer, in microseconds. */
private static final long INPUT_POLL_US = 5_000;
/**
* How long a NAL unit waits for a free input buffer before it is dropped (#89): longer
* than a frame at 30 fps, so a decoder that only falls behind for a moment loses nothing;
* meanwhile the network queue of the stream takes the backlog.
*/
static final long INPUT_WAIT_MS = 40;

private volatile MediaCodec decoder;
private final Object decoderLock = new Object();
Expand All @@ -54,6 +63,8 @@ class MediaCodecManager {
private volatile long lastFrameMs;
/** NAL units not fed because the decoder had no free input buffer: it is not keeping up. */
private volatile int inputDropped;
/** closeDecoder() calls waiting for decoderLock: the input wait gives way to them. */
private final AtomicInteger closeWaiting = new AtomicInteger();
private volatile int outWidth;
private volatile int outHeight;
/** MIME type whose instance slot this manager holds while it has a decoder (#83). */
Expand Down Expand Up @@ -187,6 +198,15 @@ private static void releaseAsync(MediaCodec codec) {

/** Release the decoder on purpose (codec switch, camera switch): no back-off. */
void closeDecoder() {
closeWaiting.incrementAndGet();
try {
closeDecoderLocked();
} finally {
closeWaiting.decrementAndGet();
}
}

private void closeDecoderLocked() {
synchronized (decoderLock) {
retry.onSuccess();
MediaCodec codec = decoder;
Expand Down Expand Up @@ -315,7 +335,17 @@ boolean decodeFrame(Frame buffer, boolean codecH265, long watchdogRef) {
if ((configSeen & needed) == needed) awaitingConfig = false;
}
try {
int inputBufferId = codec.dequeueInputBuffer(5_000);
// No free input buffer at once: give decoded frames back (the decoder may
// be waiting for output space) and try again, for up to INPUT_WAIT_MS.
// Dropping a NAL unit corrupts the picture until the next key frame (#89)
int inputBufferId = codec.dequeueInputBuffer(INPUT_POLL_US);
long waitUntil = nowMs() + INPUT_WAIT_MS;
// A close or a pause waiting for the lock ends the wait at once (UI thread)
while (inputBufferId < 0 && nowMs() < waitUntil && enabled
&& closeWaiting.get() == 0) {
drainOutput(codec);
inputBufferId = codec.dequeueInputBuffer(INPUT_POLL_US);
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}
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if (inputBufferId >= 0) {
ByteBuffer inputBuffer = codec.getInputBuffer(inputBufferId);
if (inputBuffer != null) {
Expand All @@ -324,30 +354,11 @@ boolean decodeFrame(Frame buffer, boolean codecH265, long watchdogRef) {
codec.queueInputBuffer(inputBufferId, 0,
buffer.length(), System.nanoTime() / 1000, flag);
}
} else {
} else if (enabled && closeWaiting.get() == 0) {
// Only a full wait is a decoder loss; a close or pause cut it short
inputDropped++;
}

MediaCodec.BufferInfo info = bufferInfo;
int outputBufferId;
while ((outputBufferId = codec.dequeueOutputBuffer(info, 0)) >= 0
|| outputBufferId == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
if (outputBufferId == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
MediaFormat format = codec.getOutputFormat();
int mWidth = format.getInteger(MediaFormat.KEY_WIDTH);
int mHeight = format.getInteger(MediaFormat.KEY_HEIGHT);
outWidth = mWidth;
outHeight = mHeight;
if (listener != null) {
listener.onResolutionChanged(mWidth, mHeight);
}
} else {
codec.releaseOutputBuffer(outputBufferId, true);
framesOut++;
lastFrameMs = nowMs();
retry.onSuccess(); // a decoded frame: the decoder works
}
}
drainOutput(codec);
} catch (Exception e) {
decoder = null;
releaseSlot();
Expand All @@ -362,4 +373,28 @@ boolean decodeFrame(Frame buffer, boolean codecH265, long watchdogRef) {
}
return needCreate;
}

/** Renders every decoded frame that is ready; caller holds decoderLock. */
private void drainOutput(MediaCodec codec) {
MediaCodec.BufferInfo info = bufferInfo;
int outputBufferId;
while ((outputBufferId = codec.dequeueOutputBuffer(info, 0)) >= 0
|| outputBufferId == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
if (outputBufferId == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
MediaFormat format = codec.getOutputFormat();
int mWidth = format.getInteger(MediaFormat.KEY_WIDTH);
int mHeight = format.getInteger(MediaFormat.KEY_HEIGHT);
outWidth = mWidth;
outHeight = mHeight;
if (listener != null) {
listener.onResolutionChanged(mWidth, mHeight);
}
} else {
codec.releaseOutputBuffer(outputBufferId, true);
framesOut++;
lastFrameMs = nowMs();
retry.onSuccess(); // a decoded frame: the decoder works
}
}
}
}
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