音频的MediaExtractor，获取意外的音频
使用MediaExtractor类，我可以从保存的mp4视频中获得编码后的音频样本数据，如下所示：
ByteBuffer byteBuffer = ByteBuffer.allocate(1024 * 256);
MediaExtractor audioExtractor = new MediaExtractor();
try {
int trackIndex = -1;
audioExtractor.setDataSource(originalMediaItem.getFilePath());
for (int i = 0; i < audioExtractor.getTrackCount(); i++) {
MediaFormat format = audioExtractor.getTrackFormat(i);
String mime = format.getString(MediaFormat.KEY_MIME);
if (mime.startsWith("audio/")) {
trackIndex = i;
break;
}
}
audioExtractor.selectTrack(trackIndex);
mAudioFormatMedia = audioExtractor.getTrackFormat(trackIndex);
mAudioTrackIndex = mMediaMuxer.addTrack(mAudioFormatMedia);
int size = audioExtractor.readSampleData(byteBuffer, 0);
do {
if (audioExtractor.getSampleTrackIndex() == 1) {
long presentationTime = audioExtractor.getSampleTime();
mInputBufferHashMap.put(presentationTime, byteBuffer);
audioExtractor.advance();
size = audioExtractor.readSampleData(byteBuffer, 0);
}
} while (size >= 0);
audioExtractor.release();
audioExtractor = null;
} catch (IOException e) {
e.printStackTrace();
}我有一个来自GlSurface的视频源，然后想使用MediaMuxer将此视频与前面提到的音频提取进行多路复用。在处理视频时，使用哈希图将音频交织到多路复用器中。
当我写入多路复用器时，我确实看到了预期的bufferinfo.size和bufferInfo.presentationTimeUs：
mMediaMuxer.writeSampleData(mAudioTrackIndex, buffer, mAudioBufferInfo);
Log.d(TAG, String.format("Wrote %d audio bytes at %d", mAudioBufferInfo.size, mAudioBufferInfo.presentationTimeUs));我试过使用标准的inputBuffer，outputBuffer和MediaCodec，像这样的https://gist.github.com/a-m-s/1991ab18fbcb0fcc2cf9，但这产生了相同的音频，据我所知，MediaExtractor应该已经是编码的音频数据，所以数据应该能够直接通过管道传输。
if( (audioExtractor.getSampleFlags() & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0)
Log.d(TAG, "BUFFER_FLAG_END_OF_STREAM")我现在正在质疑最初的mp4视频，是否有可能有一个mp4的不可提取的音频轨道，以及我如何可能证实这一点。
如果我当前的实现中有任何错误，任何见解都会有所帮助！
{最大比特率=512000，采样率=48000，音轨id=2，durationUs=22373187，mime=音频/MP4A-latm，profile=2，通道计数=4，language=`，aac-=2，bitrate=512000，最大输入大小=1764，csd-0=java.nio.HeapByteBufferpos=0 lim=2 cap=2}
回答 1
Stack Overflow用户
发布于 2018-07-03 08:22:47
尝试为音频数据创建映射时出现问题。AudioData不正确。我可以通过在编写videoData时批量处理音频样本数据来解决这个问题，方法如下：
private void writeAudioSampleData(
MediaExtractor audioExtractor, MediaMuxer muxer, int filterStart, int filterEnd) {
mFilterStart = filterEnd;
MediaCodec.BufferInfo audioBufferInfo = new MediaCodec.BufferInfo();
boolean audioExtractorDone = false;
audioExtractor.seekTo(filterStart, MediaExtractor.SEEK_TO_CLOSEST_SYNC);
synchronized (mAudioLockObject) {
while (!audioExtractorDone) {
try {
audioBufferInfo.size =
audioExtractor.readSampleData(audioInputBuffer, 0);
} catch (Exception e) {
e.printStackTrace();
}
if (DEBUG) {
Log.d(TAG, "audioBufferInfo.size: " + audioBufferInfo.size);
}
if (audioBufferInfo.size < 0) {
audioBufferInfo.size = 0;
audioExtractorDone = true;
} else {
audioBufferInfo.presentationTimeUs = audioExtractor.getSampleTime();
if (audioBufferInfo.presentationTimeUs > filterEnd) {
break; //out of while
}
if (audioBufferInfo.presentationTimeUs >= filterStart &&
audioBufferInfo.presentationTimeUs <= filterEnd) {
audioBufferInfo.presentationTimeUs -= mOriginalMediaItem.mRecordingStartTs;
audioBufferInfo.flags = audioExtractor.getSampleFlags();
try {
muxer.writeSampleData(mAudioTrackIndex, audioInputBuffer,
audioBufferInfo);
if (DEBUG)Log.d(TAG, String.format("Wrote %d audio bytes at %d",
audioBufferInfo.size, audioBufferInfo.presentationTimeUs));
} catch(IllegalArgumentException | IllegalStateException |
NullPointerException ignore) {}
}
audioExtractor.advance();
}
}
}https://stackoverflow.com/questions/48594218
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