I'm doing a transcoder using MediaCodec.
I created two mediacodec instance, one is for decoding and another is for encoding. I'm trying to send decoders outputBuffer directly into encoders inputBuffer.
It seems has no problem while compiling and executing.And it runs quickly. But the output video file has something wrong.I checked the metadata of the output video and they are all right : bitrate, framerate, resolution ...Only the images in the video is wrong like this:screen shot
I thought it has somethings wrong,but I cannot figure it out...
I searched libraries and documents, and I found some sample codes using Texture surface to render the decoder output data and tranfer the data into the encoder. But I thought it should not be neccessary for me. Because I dont need to edit images of the video.What I only need to do is changing the bitrate and resolution to make the file's size smaller.
here is the core code in my project:
private void decodeCore() {
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
int frameCount = 0;
while (mDecodeRunning) {
int inputBufferId = mDecoder.dequeueInputBuffer(50);
if (inputBufferId >= 0) {
// fill inputBuffers[inputBufferId] with valid data
int sampleSize = mExtractor.readSampleData(mDecodeInputBuffers[inputBufferId], 0);
if (sampleSize >= 0) {
long time = mExtractor.getSampleTime();
mDecoder.queueInputBuffer(inputBufferId, 0, sampleSize, time, 0);
} else {
mDecoder.queueInputBuffer(inputBufferId, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
}
mExtractor.advance();
}
int outputBufferId = mDecoder.dequeueOutputBuffer(bufferInfo, 50);
if (outputBufferId >= 0) {
FrameData data = mFrameDataQueue.obtain();
//wait until queue has space to push data
while (data == null) {
try {
Thread.sleep(20);
} catch (InterruptedException e) {
e.printStackTrace();
}
data = mFrameDataQueue.obtain();
}
data.data.clear();
data.size = 0;
data.offset = 0;
data.flag = 0;
data.frameTimeInUs = bufferInfo.presentationTimeUs;
// outputBuffers[outputBufferId] is ready to be processed or rendered.
if (bufferInfo.size > 0) {
ByteBuffer buffer = mDecodeOutputBuffers[outputBufferId];
buffer.position(bufferInfo.offset);
buffer.limit(bufferInfo.offset + bufferInfo.size);
data.data.put(buffer);
data.data.flip();
data.size = bufferInfo.size;
data.frameIndex = frameCount++;
}
data.flag = bufferInfo.flags;
if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) == MediaCodec.BUFFER_FLAG_END_OF_STREAM) {
Log.d("bingbing_transcode", "decode over! frames:" + (frameCount - 1));
mDecodeRunning = false;
}
mFrameDataQueue.pushToQueue(data);
mDecoder.releaseOutputBuffer(outputBufferId, false);
Log.d("bingbing_transcode", "decode output:\n frame:" + (frameCount - 1) + "\n" + "size:" + bufferInfo.size);
} else if (outputBufferId == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
mDecodeOutputBuffers = mDecoder.getOutputBuffers();
} else if (outputBufferId == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
// Subsequent data will conform to new format.
mDecodeOutputVideoFormat = mDecoder.getOutputFormat();
configureAndStartEncoder();
}
}
mDecoder.stop();
mDecoder.release();
}
private void encodeCore() {
int trackIndex = 0;
boolean muxerStarted = false;
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
int frameCount = 0;
while (mEncodeRunning) {
int inputBufferId = mEncoder.dequeueInputBuffer(50);
if (inputBufferId >= 0) {
FrameData data = mFrameDataQueue.pollFromQueue();
//wait until queue has space to push data
while (data == null) {
try {
Thread.sleep(20);
} catch (InterruptedException e) {
e.printStackTrace();
}
data = mFrameDataQueue.obtain();
}
if (data.size > 0) {
ByteBuffer inputBuffer = mEncodeInputBuffers[inputBufferId];
inputBuffer.clear();
inputBuffer.put(data.data);
inputBuffer.flip();
}
mEncoder.queueInputBuffer(inputBufferId, 0, data.size, data.frameTimeInUs, data.flag);
mFrameDataQueue.recycle(data);
}
int outputBufferId = mEncoder.dequeueOutputBuffer(bufferInfo, 50);
if (outputBufferId >= 0) {
// outputBuffers[outputBufferId] is ready to be processed or rendered.
ByteBuffer encodedData = mEncodeOutputBuffers[outputBufferId];
if (bufferInfo.size > 0) {
if (encodedData == null) {
throw new RuntimeException("encoderOutputBuffer " + outputBufferId + " was null");
}
if (!muxerStarted) {
throw new RuntimeException("muxer hasn't started");
}
frameCount++;
}
// adjust the ByteBuffer values to match BufferInfo (not needed?)
encodedData.position(bufferInfo.offset);
encodedData.limit(bufferInfo.offset + bufferInfo.size);
mMuxer.writeSampleData(trackIndex, encodedData, bufferInfo);
if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) == MediaCodec.BUFFER_FLAG_END_OF_STREAM) {
Log.d("bingbing_transcode", "encode over! frames:" + (frameCount - 1));
mEncodeRunning = false;
}
mEncoder.releaseOutputBuffer(outputBufferId, false);
Log.d("bingbing_transcode", "encode output:\n frame:" + (frameCount - 1) + "\n" + "size:" + bufferInfo.size);
} else if (outputBufferId == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
mEncodeOutputBuffers = mEncoder.getOutputBuffers();
} else if (outputBufferId == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
// should happen before receiving buffers, and should only happen once
if (muxerStarted) {
throw new RuntimeException("format changed twice");
}
MediaFormat newFormat = mEncoder.getOutputFormat();
Log.d("bingbing_transcode", "encoder output format changed: " + newFormat);
// now that we have the Magic Goodies, start the muxer
trackIndex = mMuxer.addTrack(newFormat);
mMuxer.start();
muxerStarted = true;
mEncodeOutputVideoFormat = newFormat;
}
}
mEncoder.stop();
mEncoder.release();
if (muxerStarted) {
mMuxer.stop();
mMuxer.release();
}
}
these two functions run in two different threads.
FrameData is a simple storage of frame bytebuffer and frame present time and something needed
