问题
I am decoding a h264 video stream with the following code (original guide):
public void configure(Surface surface, int width, int height, ByteBuffer csd0) {
String VIDEO_FORMAT = "video/avc";
if (mConfigured) {
throw new IllegalStateException("Decoder is already configured");
}
MediaFormat format = MediaFormat.createVideoFormat(VIDEO_FORMAT, width, height);
// little tricky here, csd-0 is required in order to configure the codec properly
// it is basically the first sample from encoder with flag: BUFFER_FLAG_CODEC_CONFIG
format.setByteBuffer("csd-0", csd0);
try {
mCodec = MediaCodec.createDecoderByType(VIDEO_FORMAT);
} catch (IOException e) {
throw new RuntimeException("Failed to create codec", e);
}
mCodec.configure(format, surface, null, 0);
mCodec.start();
mConfigured = true;
}
@SuppressWarnings("deprecation")
public void decodeSample(byte[] data, int offset, int size, long presentationTimeUs, int flags) {
if (mConfigured && mRunning) {
int index = mCodec.dequeueInputBuffer(mTimeoutUs);
if (index >= 0) {
ByteBuffer buffer;
// since API 21 we have new API to use
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
buffer = mCodec.getInputBuffers()[index];
buffer.clear();
} else {
buffer = mCodec.getInputBuffer(index);
}
if (buffer != null) {
buffer.put(data, offset, size);
mCodec.queueInputBuffer(index, 0, size, presentationTimeUs, flags);
}
}
}
}
@Override
public void run() {
try {
MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
while (mRunning) {
if (mConfigured) {
int index = mCodec.dequeueOutputBuffer(info, mTimeoutUs);
if (index >= 0) {
// setting true is telling system to render frame onto Surface
mCodec.releaseOutputBuffer(index, true);
if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) == MediaCodec.BUFFER_FLAG_END_OF_STREAM) {
break;
}
}
} else {
// just waiting to be configured, then decode and render
try {
Thread.sleep(10);
} catch (InterruptedException ignore) {
}
}
}
} finally {
if (mConfigured) {
mCodec.stop();
mCodec.release();
}
}
}
I can run this on both my Nexus 6 (api 22) and Samsung galaxy core (api 16) on low and medium quality. However when I switch to high quality (720p) it crashes on the Samsung after about 30 frames (but nothing is rendered to the screen).
E/ACodec﹕ [OMX.qcom.video.decoder.avc] ERROR(0x8000100a)
E/MediaCodec﹕ Codec reported an error. (omx error 0x8000100a, internalError -2147483648)
[...]
W/System.err﹕ java.lang.IllegalStateException
W/System.err﹕ at android.media.MediaCodec.dequeueInputBuffer(Native Method)
W/System.err﹕ at com.test.stream.VideoDecoder$Worker.decodeSample(VideoDecoder.java:95)
W/System.err﹕ at com.test.stream.VideoDecoder.decodeSample(VideoDecoder.java:24)
W/System.err﹕ at com.test.stream.VideoThread.run(VideoThread.java:160)
The error above is the first error that appears, the IllegalStateException is afterwards thrown on each frame.
My question is, is this a device specific problem (because of: older api/device, less powerful, etc.) or is something actually wrong? and how should I deal with this?
回答1:
For my Android h.264 decoder i do it slightly different to your setup. I think your using more modern api level. But for me it looks more like this:
public void startDecoder() {
// Initilize codec
mediaCodec = MediaCodec.createDecoderByType("video/avc");
mediaFormat = MediaFormat.createVideoFormat("video/avc", 0, 0);
bufferInfo = new MediaCodec.BufferInfo();
// STOPS unit-tests from crashing here from mocked out android
if (mediaCodec != null) {
mediaCodec.configure(mediaFormat, targetSurface, null, 0);
mediaCodec.start();
decoderThread = new Thread(this);
decoderThread.start();
}
}
// Decoder Thread refers to this class which does the decoder/render loop:
public void run() {
//mediaCodec input + output dequeue timeouts
long kInputBufferTimeoutMs = 50;
long kOutputBufferTimeoutMs = 50;
while (running && mediaCodec != null) {
synchronized (mediaCodec) {
// stop if not running.
if (!running || mediaCodec == null)
break;
// Only push in new data if there is data available in the queue
if (naluSegmentQueue.size() > 0) {
int inputBufferIndex = mediaCodec.dequeueInputBuffer(kInputBufferTimeoutMs);
if (inputBufferIndex >= 0) {
NaluSegment segment = naluSegmentQueue.poll();
codecInputBufferAvailable(segment, mediaCodec, inputBufferIndex);
}
}
// always check if output is available.
int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, kOutputBufferTimeoutMs);
if (outputBufferIndex >= 0) {
// Try and render first
codecOuputBufferAvailable(mediaCodec, outputBufferIndex, bufferInfo);
} else if (outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
// Subsequent data will conform to new format.
// Can ignore if using getOutputFormat(outputBufferId)
mediaFormat = mediaCodec.getOutputFormat();
}
}
}
}
To put data into the decoder including the parameters. I don't bother with trying to use the csd-0/1 network streams can have changing format descriptions and its easier to just let it be picked up dynamically.
private void codecInputBufferAvailable(NaluSegment segment, MediaCodec codec, int index) {
int flags = (segment.getType() == NaluType.SPS
|| segment.getType() == NaluType.PPS
|| segment.getType() == NaluType.SUPP_ENHANCEMENT) ?
MediaCodec.BUFFER_FLAG_CODEC_CONFIG : MediaCodec.BUFFER_FLAG_SYNC_FRAME;
ByteBuffer[] buffers = codec.getInputBuffers();
ByteBuffer buffer = buffers[index];
// Can throw buffer overflow exception when buffer sizes are too small.
try {
buffer.put(segment.getBuffer());
codec.queueInputBuffer(index, 0, segment.getBufferSize(), 0, flags);
} catch(Exception e) {
Log.e(TAG, "Failed to push buffer to decoder");
}
}
IMPORTANT: buffer.put(segment.getBuffer()); getBuffer() here always returns a 4 byte annexb buffer. The android decoders do not understand 3 byte nal units. So if you have a 3 byte nal unit turn it into 4 bytes magic sequence with length + 1 and 0x00, 0x00, 0x00, 0x01 as the start magic sequence the rest of the buffer should be &buffer[headerLength].
Notice the try-catch here this doesn't give a compiler warning but it can throw a buffer overflow exception here if your have a very big payload and the byte-buffer is too small.
So long as your parse out your NAL units correctly this should work for you. But for my case i noticed that the NAL units can be 3 or 4 bytes for the magic header.
/**
* H264 is comprised of NALU segments.
*
* XXXX Y ZZZZZZZZ -> XXXX Y ZZZZZZZZ -> XXXX Y ZZZZZZZZ
*
* Each segment is comprised of:
*
* XXXX -> Magic byte header (0x00, 0x00, 0x00, 0x01) NOTE: this can be either 3 of 4 bytes
* Y -> The Nalu Type
* ZZZ... -> The Payload
*
* Notice there is no nalu length specified. To parse an nalu, you must
* read until the next magic-byte-sequence AKA the next segment to figure
* out the full nalu length
**/
public static List<NaluSegment> parseNaluSegments(byte[] buffer) throws NaluBufferException {
List<NaluSegment> segmentList = new ArrayList<>();
if (buffer.length < 6) {
return segmentList;
}
int lastStartingOffset = -1;
for (int i = 0; i < buffer.length - 10; ++i) {
**if (buffer[i] == 0x00 && buffer[i+1] == 0x00 && buffer[i+2] == 0x01)** {
int naluType = (buffer[i+3] & 0x1F);
NaluSegment segment = new NaluSegment(naluType, 3, i);
**if (i > 0 && buffer[i-1] == 0x00)** {
// This is actually a 4 byte segment
int currentSegmentOffset = segment.getOffset();
segment.setHeaderSize(4);
segment.setOffset(currentSegmentOffset - 1);
}
...
Create your own nalu-segment objects and don't forget the trailing NAL.
I hope this helps.
来源：https://stackoverflow.com/questions/32841513/mediacodec-crash-on-high-quality-stream