重新编码采用Android媒体codeC H.264内容不同的比特率比特率、不同、媒体、内容
我试图重新带采用的是Android媒体codeC API在4.2推出了不同的比特率codeA H.264的MP4文件。
I'm attempting to re-encode a h.264 mp4 file with a different bit rate using the Android MediaCodec API's introduced in 4.2.
我能去code和播放内容（前改变比特率），使用媒体codeC API，但如果我尝试重新连接code有不同的比特率的内容解码它之前我得到乱码了认沽（绿屏的灰色像素化）。
I am able decode and play the content (prior to changing the bit rate) using the MediaCodec API but if I attempt to re-encode the content with a different bit rate prior to decoding it I get garbled out put (a green screen with grey pixelation).
在code我使用的是基于Android的测试用例android.media.cts.De coderTest Android的测试用例android.media.cts.De coderTest ：
The code I am using is based on the Android Test Case android.media.cts.DecoderTest Android Test Case android.media.cts.DecoderTest:
public void encodeDecodeVideoFile(AssetFileDescriptor assetFileDescriptor) {
int bitRate = 500000;
int frameRate = 30;
int width = 480;
int height = 368;
String mimeType = "video/avc";
MediaCodec encoder, decoder = null;
ByteBuffer[] encoderInputBuffers;
ByteBuffer[] encoderOutputBuffers;
ByteBuffer[] decoderInputBuffers = null;
ByteBuffer[] decoderOutputBuffers = null;
// Find a code that supports the mime type
int numCodecs = MediaCodecList.getCodecCount();
MediaCodecInfo codecInfo = null;
for (int i = 0; i < numCodecs && codecInfo == null; i++) {
MediaCodecInfo info = MediaCodecList.getCodecInfoAt(i);
if (!info.isEncoder()) {
continue;
}
String[] types = info.getSupportedTypes();
boolean found = false;
for (int j = 0; j < types.length && !found; j++) {
if (types[j].equals(mimeType))
found = true;
}
if (!found)
continue;
codecInfo = info;
}
Log.d(TAG, "Found " + codecInfo.getName() + " supporting " + mimeType);
// Find a color profile that the codec supports
int colorFormat = 0;
MediaCodecInfo.CodecCapabilities capabilities = codecInfo.getCapabilitiesForType(mimeType);
for (int i = 0; i < capabilities.colorFormats.length && colorFormat == 0; i++) {
int format = capabilities.colorFormats[i];
switch (format) {
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedSemiPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_TI_FormatYUV420PackedSemiPlanar:
colorFormat = format;
break;
default:
Log.d(TAG, "Skipping unsupported color format " + format);
break;
}
}
Log.d(TAG, "Using color format " + colorFormat);
// Determine width, height and slice sizes
if (codecInfo.getName().equals("OMX.TI.DUCATI1.VIDEO.H264E")) {
// This codec doesn't support a width not a multiple of 16,
// so round down.
width &= ~15;
}
int stride = width;
int sliceHeight = height;
if (codecInfo.getName().startsWith("OMX.Nvidia.")) {
stride = (stride + 15) / 16 * 16;
sliceHeight = (sliceHeight + 15) / 16 * 16;
}
// Used MediaExtractor to select the first track from the h.264 content
MediaExtractor extractor = new MediaExtractor();
extractor.setDataSource(assetFileDescriptor.getFileDescriptor(), assetFileDescriptor.getStartOffset(), assetFileDescriptor.getLength());
MediaFormat extractedFormat = extractor.getTrackFormat(0);
String mime = extractedFormat.getString(MediaFormat.KEY_MIME);
Log.d(TAG, "Extartced Mime " + mime);
extractor.selectTrack(0);
// Create an encoder
encoder = MediaCodec.createByCodecName(codecInfo.getName());
MediaFormat inputFormat = MediaFormat.createVideoFormat(mimeType, width, height);
inputFormat.setInteger(MediaFormat.KEY_BIT_RATE, bitRate);
inputFormat.setInteger(MediaFormat.KEY_FRAME_RATE, frameRate);
inputFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, colorFormat);
inputFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 5);
inputFormat.setInteger("stride", stride);
inputFormat.setInteger("slice-height", sliceHeight);
Log.d(TAG, "Configuring encoder with input format " + inputFormat);
encoder.configure(inputFormat, null /* surface */, null /* crypto */, MediaCodec.CONFIGURE_FLAG_ENCODE);
encoder.start();
encoderInputBuffers = encoder.getInputBuffers();
encoderOutputBuffers = encoder.getOutputBuffers();
// start encoding + decoding
final long kTimeOutUs = 5000;
MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
boolean sawInputEOS = false;
boolean sawOutputEOS = false;
MediaFormat oformat = null;
long startMs = System.currentTimeMillis();
while (!sawOutputEOS) {
if (!sawInputEOS) {
int inputBufIndex = encoder.dequeueInputBuffer(kTimeOutUs);
if (inputBufIndex >= 0) {
ByteBuffer dstBuf = encoderInputBuffers[inputBufIndex];
int sampleSize = extractor.readSampleData(dstBuf, 0 /* offset */);
long presentationTimeUs = 0;
if (sampleSize < 0) {
Log.d(TAG, "saw input EOS.");
sawInputEOS = true;
sampleSize = 0;
} else {
presentationTimeUs = extractor.getSampleTime();
}
encoder.queueInputBuffer(inputBufIndex, 0 /* offset */, sampleSize, presentationTimeUs, sawInputEOS ? MediaCodec.BUFFER_FLAG_END_OF_STREAM : 0);
if (!sawInputEOS) {
extractor.advance();
}
}
}
int res = encoder.dequeueOutputBuffer(info, kTimeOutUs);
if (res >= 0) {
int outputBufIndex = res;
ByteBuffer buf = encoderOutputBuffers[outputBufIndex];
buf.position(info.offset);
buf.limit(info.offset + info.size);
if ((info.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
// create a decoder
decoder = MediaCodec.createDecoderByType(mimeType);
MediaFormat format = MediaFormat.createVideoFormat(mimeType, width, height);
format.setInteger(MediaFormat.KEY_COLOR_FORMAT, colorFormat);
format.setByteBuffer("csd-0", buf);
decoder.configure(format, surface /* surface */, null /* crypto */, 0 /* flags */);
decoder.start();
decoderInputBuffers = decoder.getInputBuffers();
decoderOutputBuffers = decoder.getOutputBuffers();
} else {
int decIndex = decoder.dequeueInputBuffer(-1);
decoderInputBuffers[decIndex].clear();
decoderInputBuffers[decIndex].put(buf);
decoder.queueInputBuffer(decIndex, 0, info.size, info.presentationTimeUs, info.flags);
}
encoder.releaseOutputBuffer(outputBufIndex, false /* render */);
} else if (res == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
encoderOutputBuffers = encoder.getOutputBuffers();
Log.d(TAG, "encoder output buffers have changed.");
} else if (res == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
MediaFormat encformat = encoder.getOutputFormat();
Log.d(TAG, "encoder output format has changed to " + encformat);
}
if (decoder == null)
res = MediaCodec.INFO_TRY_AGAIN_LATER;
else
res = decoder.dequeueOutputBuffer(info, kTimeOutUs);
if (res >= 0) {
int outputBufIndex = res;
ByteBuffer buf = decoderOutputBuffers[outputBufIndex];
buf.position(info.offset);
buf.limit(info.offset + info.size);
// The worlds simplest FPS implementation
while (info.presentationTimeUs / 1000 > System.currentTimeMillis() - startMs) {
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
break;
}
}
decoder.releaseOutputBuffer(outputBufIndex, true /* render */);
if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
Log.d(TAG, "saw output EOS.");
sawOutputEOS = true;
}
} else if (res == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
decoderOutputBuffers = decoder.getOutputBuffers();
Log.d(TAG, "decoder output buffers have changed.");
} else if (res == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
oformat = decoder.getOutputFormat();
Log.d(TAG, "decoder output format has changed to " + oformat);
}
}
encoder.stop();
encoder.release();
decoder.stop();
decoder.release();
}
我想该文件EN code是从Android CTS测试项目：
The file I am trying to encode is from the Android cts Test Project:
R.raw.video_480x360_mp4_h264_1000kbps_30fps_aac_stereo_128kbps_44100hz
R.raw.video_480x360_mp4_h264_1000kbps_30fps_aac_stereo_128kbps_44100hz
我猜问题是相关的格式参数我指定的EN codeR媒体codeC，但我无法弄清楚什么是不正确/缺失。
I'm guessing the problem is related to the format parameters I am specifying in the encoder MediaCodec but I can't figure out what is incorrect/missing.
推荐答案
在你的程序中，有一个设计问题。在循环而（！sawOutputEOS）{，你正在尝试重新连接code，
In your program, there is a design issue. In the loop while (!sawOutputEOS) { where you are trying to re-encode,
int inputBufIndex = encoder.dequeueInputBuffer(kTimeOutUs);
离队一个缓冲来自输入/输入端口连接codeR
Dequeues one buffer from the input / input port of the encoder
ByteBuffer dstBuf = encoderInputBuffers[inputBufIndex];
缓冲区指针出列缓冲
Buffer pointer to the dequeued buffer
int sampleSize = extractor.readSampleData(dstBuf, 0 /* offset */);
该出队缓冲器填充有从提取的数据。提取器的输出是一个COM pressed比特流。这是不是YUV uncom pressed框架。
The dequeued buffer is filled with the data from extractor. The output of an extractor is a compressed bitstream. This is not a YUV uncompressed frame.
encoder.queueInputBuffer(inputBufIndex,....)
在这里，COM pressed比特流是连接codeD。因为这不是一个YUV帧时，EN codeR将尝试执行COM pression尽它的能力，因此，你看到一个绿色的字迹模糊帧的EN codeR输出。我presume你在屏幕上观察这是由于code以下部分，你c中的相同的内容去$ C $。这已经观察到，即使连接codeR的输出被写进文件，并通过不同的播放器或PC上播放。
Here, the compressed bitstream is encoded. Since this is not a YUV frame, the encoder will try to perform a compression to the best of it's ability and hence, you observe a green illegible frame at the output of the encoder. I presume you are observing this on the screen due to the following portion of code where you decode the same content. This would have been observed even if the encoder's output was written into a file and played through a different player or on PC.
从程序，我presume你的设计意图是德code ==＆GT;恩code ==＆GT;直播德code 的，你的图应该是
From the program, I presume your intended design is Decode ==> Encode ==> Live Decode for which your graph should be
MediaExtractor ==> MediaCodec (Decoder) ==> MediaCodec (Encoder) ==> MediaCodec (Decoder) ==> Display
PS：你有没有发现任何违规的内存，当您运行这个程序？
P.S: Did you observe any memory violations when you run this program?
