一、MediaExtractor API介绍
MediaExtractor的作用是把音频和视频的数据进行分离。
主要API介绍：
- setDataSource(String path)：即可以设置本地文件又可以设置网络文件
- getTrackCount()：得到源文件通道数
- getTrackFormat(int index)：获取指定（index）的通道格式
- getSampleTime()：返回当前的时间戳
- readSampleData(ByteBuffer byteBuf, int offset)：把指定通道中的数据按偏移量读取到ByteBuffer中；
- advance()：读取下一帧数据
- release(): 读取结束后释放资源
MediaExtractor 的使用主要有这么几步：
- 设置数据源
- 获取通道数，切换到想要的轨道
- 循环读取每帧的样本数据
- 完成后释放资源
MP4视频分离成音频和视频示例：
private void exactorMedia() {
FileOutputStream videoOutputStream = null;
FileOutputStream audioOutputStream = null;
try {
//分离的视频文件
File videoFile = new File(SDCARD_PATH, "output_video.mp4");
//分离的音频文件
File audioFile = new File(SDCARD_PATH, "output_audios.mp3");
videoOutputStream = new FileOutputStream(videoFile);
audioOutputStream = new FileOutputStream(audioFile);
//源文件
mediaExtractor.setDataSource(SDCARD_PATH + "720p.mp4");
//信道总数
int trackCount = mediaExtractor.getTrackCount();
int audioTrackIndex = -1;
int videoTrackIndex = -1;
for (int i = 0; i < trackCount; i++) {
MediaFormat trackFormat = mediaExtractor.getTrackFormat(i);
String mineType = trackFormat.getString(MediaFormat.KEY_MIME);
//视频信道
if (mineType.startsWith("video/")) {
videoTrackIndex = i;
}
//音频信道
if (mineType.startsWith("audio/")) {
audioTrackIndex = i;
}
}
ByteBuffer byteBuffer = ByteBuffer.allocate(500 * 1024);
//切换到视频信道
mediaExtractor.selectTrack(videoTrackIndex);
while (true) {
int readSampleCount = mediaExtractor.readSampleData(byteBuffer, 0);
if (readSampleCount < 0) {
Log.d("dimen", "视频分离完成 ");
break;
}
//保存视频信道信息
byte[] buffer = new byte[readSampleCount];
byteBuffer.get(buffer);
videoOutputStream.write(buffer);
byteBuffer.clear();
mediaExtractor.advance();
}
//切换到音频信道
mediaExtractor.selectTrack(audioTrackIndex);
while (true) {
int readSampleCount = mediaExtractor.readSampleData(byteBuffer, 0);
if (readSampleCount < 0) {
Log.d("dimen", "音频分离完成 ");
break;
}
//保存音频信息
byte[] buffer = new byte[readSampleCount];
byteBuffer.get(buffer);
audioOutputStream.write(buffer);
byteBuffer.clear();
mediaExtractor.advance();
}
} catch (IOException e) {
e.printStackTrace();
} finally {
mediaExtractor.release();
try {
videoOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}二、MediaMuxer API介绍
MediaMuxer的作用是生成音频或视频文件；还可以把音频与视频混合成一个音视频文件。
相关API介绍：
- MediaMuxer(String path, int format)：path:输出文件的名称 format:输出文件的格式；当前只支持MP4格式；
- addTrack(MediaFormat format)：添加通道；我们更多的是使用MediaCodec.getOutpurForma()或Extractor.getTrackFormat(int index)来获取MediaFormat;也可以自己创建；
- start()：开始合成文件
- writeSampleData(int trackIndex, ByteBuffer byteBuf, MediaCodec.BufferInfo bufferInfo)：把ByteBuffer中的数据写入到在构造器设置的文件中；
- stop()：停止合成文件
- release()：释放资源
MediaMuxer的使用步骤：
- 设置目标文件路径和音视频格式
- 添加要合成的轨道，包括音轨和视轨
- 开始合成，循环写入每帧样本数据
- 完成后释放
纯视频分离的实例：
private void SeparateVideo() {
int videoIndex = -1;
try {
mediaExtractor.setDataSource(SDCARD_PATH + "720p.mp4");
int trackCount = mediaExtractor.getTrackCount();
for (int i = 0; i < trackCount; i++) {
MediaFormat trackFormat = mediaExtractor.getTrackFormat(i);
String mimeType = trackFormat.getString(MediaFormat.KEY_MIME);
// 取出视频的信号
if (mimeType.startsWith("video/")) {
videoIndex = i;
}
}
//切换道视频信号的信道
mediaExtractor.selectTrack(videoIndex);
MediaFormat trackFormat = mediaExtractor.getTrackFormat(videoIndex);
mediaMuxer = new MediaMuxer(SDCARD_PATH + "/output_video2.mp4", MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
//追踪此信道
int trackIndex = mediaMuxer.addTrack(trackFormat);
ByteBuffer byteBuffer = ByteBuffer.allocate(1024 * 500);
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
mediaMuxer.start();
long videoSampleTime;
//获取每帧的之间的时间
{
mediaExtractor.readSampleData(byteBuffer, 0);
//skip first I frame
if (mediaExtractor.getSampleFlags() == MediaExtractor.SAMPLE_FLAG_SYNC)
mediaExtractor.advance();
mediaExtractor.readSampleData(byteBuffer, 0);
long firstVideoPTS = mediaExtractor.getSampleTime();
mediaExtractor.advance();
mediaExtractor.readSampleData(byteBuffer, 0);
long SecondVideoPTS = mediaExtractor.getSampleTime();
videoSampleTime = Math.abs(SecondVideoPTS - firstVideoPTS);
Log.d("dimen", "videoSampleTime is " + videoSampleTime);
}
//重新切换此信道，不然上面跳过了3帧,造成前面的帧数模糊
mediaExtractor.unselectTrack(videoIndex);
mediaExtractor.selectTrack(videoIndex);
while (true) {
//读取帧之间的数据
int readSampleSize = mediaExtractor.readSampleData(byteBuffer, 0);
if (readSampleSize < 0) {
break;
}
mediaExtractor.advance();
bufferInfo.size = readSampleSize;
bufferInfo.offset = 0;
bufferInfo.flags = mediaExtractor.getSampleFlags();
bufferInfo.presentationTimeUs += videoSampleTime;
//写入帧的数据
mediaMuxer.writeSampleData(trackIndex, byteBuffer, bufferInfo);
}
//release
mediaMuxer.stop();
mediaExtractor.release();
mediaMuxer.release();
Log.e("dimen", "finish");
} catch (IOException e) {
e.printStackTrace();
}
}分离纯音频的示例：
private void SeparateAudio() {
int audioIndex = -1;
try {
mediaExtractor.setDataSource(SDCARD_PATH + "720p.mp4");
int trackCount = mediaExtractor.getTrackCount();
for (int i = 0; i < trackCount; i++) {
MediaFormat trackFormat = mediaExtractor.getTrackFormat(i);
if (trackFormat.getString(MediaFormat.KEY_MIME).startsWith("audio/")) {
audioIndex = i;
}
}
mediaExtractor.selectTrack(audioIndex);
MediaFormat trackFormat = mediaExtractor.getTrackFormat(audioIndex);
mediaMuxer = new MediaMuxer(SDCARD_PATH + "/output_audios2.mp3", MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
int writeAudioIndex = mediaMuxer.addTrack(trackFormat);
mediaMuxer.start();
ByteBuffer byteBuffer = ByteBuffer.allocate(500 * 1024);
MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
long stampTime = 0;
//获取帧之间的间隔时间
{
mediaExtractor.readSampleData(byteBuffer, 0);
if (mediaExtractor.getSampleFlags() == MediaExtractor.SAMPLE_FLAG_SYNC) {
mediaExtractor.advance();
}
mediaExtractor.readSampleData(byteBuffer, 0);
long secondTime = mediaExtractor.getSampleTime();
mediaExtractor.advance();
mediaExtractor.readSampleData(byteBuffer, 0);
long thirdTime = mediaExtractor.getSampleTime();
stampTime = Math.abs(thirdTime - secondTime);
Log.e("dimen", stampTime + "");
}
mediaExtractor.unselectTrack(audioIndex);
mediaExtractor.selectTrack(audioIndex);
while (true) {
int readSampleSize = mediaExtractor.readSampleData(byteBuffer, 0);
if (readSampleSize < 0) {
break;
}
mediaExtractor.advance();
bufferInfo.size = readSampleSize;
bufferInfo.flags = mediaExtractor.getSampleFlags();
bufferInfo.offset = 0;
bufferInfo.presentationTimeUs += stampTime;
mediaMuxer.writeSampleData(writeAudioIndex, byteBuffer, bufferInfo);
}
mediaMuxer.stop();
mediaMuxer.release();
mediaExtractor.release();
Log.e("dimen", "finish");
} catch (IOException e) {
e.printStackTrace();
}
}纯音频和纯视频合成示例：
private void SynthesisAudioVideo() {
try {
MediaExtractor videoExtractor = new MediaExtractor();
videoExtractor.setDataSource(SDCARD_PATH + "output_video2.mp4");
MediaFormat videoFormat = null;
int videoTrackIndex = -1;
int videoTrackCount = videoExtractor.getTrackCount();
for (int i = 0; i < videoTrackCount; i++) {
videoFormat = videoExtractor.getTrackFormat(i);
String mimeType = videoFormat.getString(MediaFormat.KEY_MIME);
if (mimeType.startsWith("video/")) {
videoTrackIndex = i;
break;
}
}
MediaExtractor audioExtractor = new MediaExtractor();
audioExtractor.setDataSource(SDCARD_PATH + "output_audios2.mp3");
MediaFormat audioFormat = null;
int audioTrackIndex = -1;
int audioTrackCount = audioExtractor.getTrackCount();
for (int i = 0; i < audioTrackCount; i++) {
audioFormat = audioExtractor.getTrackFormat(i);
String mimeType = audioFormat.getString(MediaFormat.KEY_MIME);
if (mimeType.startsWith("audio/")) {
audioTrackIndex = i;
break;
}
}
videoExtractor.selectTrack(videoTrackIndex);
audioExtractor.selectTrack(audioTrackIndex);
MediaCodec.BufferInfo videoBufferInfo = new MediaCodec.BufferInfo();
MediaCodec.BufferInfo audioBufferInfo = new MediaCodec.BufferInfo();
MediaMuxer mediaMuxer = new MediaMuxer(SDCARD_PATH + "/output.mp4", MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
int writeVideoTrackIndex = mediaMuxer.addTrack(videoFormat);
int writeAudioTrackIndex = mediaMuxer.addTrack(audioFormat);
mediaMuxer.start();
ByteBuffer byteBuffer = ByteBuffer.allocate(500 * 1024);
long sampleTime = 0;
{
videoExtractor.readSampleData(byteBuffer, 0);
if (videoExtractor.getSampleFlags() == MediaExtractor.SAMPLE_FLAG_SYNC) {
videoExtractor.advance();
}
videoExtractor.readSampleData(byteBuffer, 0);
long secondTime = videoExtractor.getSampleTime();
videoExtractor.advance();
long thirdTime = videoExtractor.getSampleTime();
sampleTime = Math.abs(thirdTime - secondTime);
}
videoExtractor.unselectTrack(videoTrackIndex);
videoExtractor.selectTrack(videoTrackIndex);
while (true) {
int readVideoSampleSize = videoExtractor.readSampleData(byteBuffer, 0);
if (readVideoSampleSize < 0) {
break;
}
videoBufferInfo.size = readVideoSampleSize;
videoBufferInfo.presentationTimeUs += sampleTime;
videoBufferInfo.offset = 0;
videoBufferInfo.flags = videoExtractor.getSampleFlags();
mediaMuxer.writeSampleData(writeVideoTrackIndex, byteBuffer, videoBufferInfo);
videoExtractor.advance();
}
while (true) {
int readAudioSampleSize = audioExtractor.readSampleData(byteBuffer, 0);
if (readAudioSampleSize < 0) {
break;
}
audioBufferInfo.size = readAudioSampleSize;
audioBufferInfo.presentationTimeUs += sampleTime;
audioBufferInfo.offset = 0;
audioBufferInfo.flags = videoExtractor.getSampleFlags();
mediaMuxer.writeSampleData(writeAudioTrackIndex, byteBuffer, audioBufferInfo);
audioExtractor.advance();
}
mediaMuxer.stop();
mediaMuxer.release();
videoExtractor.release();
audioExtractor.release();
} catch (IOException e) {
e.printStackTrace();
}
}项目地址：https://github.com/ChloeDimen/AudioAndVideo