MediaExtractor是用于提取媒体数据轨道的Android类,它不会在提取过程中修改提取的数据。因此,我们需要自己处理媒体数据以删除ADTS头信息。
以下是示例代码,用于从AAC文件中提取音频轨道并删除ADTS头信息:
MediaExtractor extractor = new MediaExtractor(); extractor.setDataSource("/path/to/aac/file"); int numTracks = extractor.getTrackCount(); int audioTrackIndex = -1; for (int i = 0; i < numTracks; i++) { MediaFormat format = extractor.getTrackFormat(i); String mime = format.getString(MediaFormat.KEY_MIME); if (mime.startsWith("audio/")) { audioTrackIndex = i; break; } } extractor.selectTrack(audioTrackIndex);
MediaCodec codec = MediaCodec.createDecoderByType(mime); codec.configure(format, null, null, 0); codec.start();
ByteBuffer[] inputBuffers = codec.getInputBuffers(); ByteBuffer[] outputBuffers = codec.getOutputBuffers(); MediaCodec.BufferInfo info = new MediaCodec.BufferInfo(); boolean isEOS = false; while (!isEOS) { int inIndex = codec.dequeueInputBuffer(10000); if (inIndex >= 0) { ByteBuffer buffer = inputBuffers[inIndex]; int sampleSize = extractor.readSampleData(buffer, 0); if (sampleSize < 0) { codec.queueInputBuffer(inIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM); isEOS = true; } else { codec.queueInputBuffer(inIndex, 0, sampleSize, extractor.getSampleTime(), 0); extractor.advance(); } }
int outIndex = codec.dequeueOutputBuffer(info, 10000);
switch (outIndex) {
case MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED:
outputBuffers = codec.getOutputBuffers();
break;
case MediaCodec.INFO_OUTPUT_FORMAT_CHANGED:
MediaFormat newFormat = codec.getOutputFormat();
// do something with newFormat
break;
case MediaCodec.INFO_TRY_AGAIN_LATER:
// do nothing
break;
default:
ByteBuffer outBuffer = outputBuffers[outIndex];
byte[] data = new byte[info.size];
outBuffer.get(data);
if ((info.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
// this buffer contains codec-specific configuration data
// skip it
} else {
// remove ADTS header from AAC buffer
int bytesRemoved = removeAdtsHeader(data, info.size);
codec.queueOutputBuffer(outIndex, 0, info.size - bytesRemoved, info.presentationTimeUs, info.flags);
}
codec.releaseOutputBuffer(outIndex, false);
break;
}
}
codec.stop(); codec.release(); extractor.release();
private static final int ADTS_HEADER_SIZE = 7; private static int removeAdtsHeader(byte[] data, int size) { int numRemoved = 0; while (size >= ADTS_HEADER_SIZE) { // check if the buffer starts with ADTS header int sync = ((data[0] & 0xff) << 4) | ((data[1] & 0xff) >> 4); if (sync != 0xfff) { break; // not ADTS header } // calculate size of ADTS header, and remove it from buffer int headerSize = ((data[3] & 0x03) << 11