前言
最近工作中遇到了音视频处理的需求，android下音视频合成，在当前调研方案中主要有三大类方法：mediamux硬解码，mp4parser，ffmepg。三种方法均可实现，但是也有不同的局限和问题，先将实现和问题记录于此，便于之后的总结学习。下面话不多说了，来一起看看详细的介绍吧。
方法一（fail）
利用mediamux实现音视频的合成。
效果：可以实现音视频的合并，利用android原生的videoview和surfaceview播放正常，大部分的播放器也播放正常，但是，但是，在上传youtube就会出现问题：音频不连续，分析主要是上传youtube时会被再次的压缩，可能在压缩的过程中出现音频的帧率出现问题。
分析：在mediacodec.bufferinfo的处理中，时间戳presentationtimeus出现问题，导致youtube的压缩造成音频的紊乱。
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public static void muxvideoandaudio(string videopath, string audiopath, string muxpath) {
try {
mediaextractor videoextractor = new mediaextractor();
videoextractor.setdatasource(videopath);
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(audiopath);
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(muxpath, 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;
//noinspection wrongconstant
videobufferinfo.flags = mediacodec.buffer_flag_sync_frame;//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;
//noinspection wrongconstant
audiobufferinfo.flags = mediacodec.buffer_flag_sync_frame;// videoextractor.getsampleflags()
mediamuxer.writesampledata(writeaudiotrackindex, bytebuffer, audiobufferinfo);
audioextractor.advance();
}
mediamuxer.stop();
mediamuxer.release();
videoextractor.release();
audioextractor.release();
} catch (ioexception e) {
e.printstacktrace();
}
}
方法二（success）
public static void muxvideoaudio(string videofilepath, string audiofilepath, string outputfile) {
try {
mediaextractor videoextractor = new mediaextractor();
videoextractor.setdatasource(videofilepath);
mediaextractor audioextractor = new mediaextractor();
audioextractor.setdatasource(audiofilepath);
mediamuxer muxer = new mediamuxer(outputfile, mediamuxer.outputformat.muxer_output_mpeg_4);
videoextractor.selecttrack(0);
mediaformat videoformat = videoextractor.gettrackformat(0);
int videotrack = muxer.addtrack(videoformat);
audioextractor.selecttrack(0);
mediaformat audioformat = audioextractor.gettrackformat(0);
int audiotrack = muxer.addtrack(audioformat);
logutil.d(tag, "video format " + videoformat.tostring());
logutil.d(tag, "audio format " + audioformat.tostring());
boolean saweos = false;
int framecount = 0;
int offset = 100;
int samplesize = 256 * 1024;
bytebuffer videobuf = bytebuffer.allocate(samplesize);
bytebuffer audiobuf = bytebuffer.allocate(samplesize);
mediacodec.bufferinfo videobufferinfo = new mediacodec.bufferinfo();
mediacodec.bufferinfo audiobufferinfo = new mediacodec.bufferinfo();
videoextractor.seekto(0, mediaextractor.seek_to_closest_sync);
audioextractor.seekto(0, mediaextractor.seek_to_closest_sync);
muxer.start();
while (!saweos) {
videobufferinfo.offset = offset;
videobufferinfo.size = videoextractor.readsampledata(videobuf, offset);
if (videobufferinfo.size < 0 || audiobufferinfo.size < 0) {
saweos = true;
videobufferinfo.size = 0;
} else {
videobufferinfo.presentationtimeus = videoextractor.getsampletime();
//noinspection wrongconstant
videobufferinfo.flags = videoextractor.getsampleflags();
muxer.writesampledata(videotrack, videobuf, videobufferinfo);
videoextractor.advance();
framecount++;
}
}
boolean saweos2 = false;
int framecount2 = 0;
while (!saweos2) {
framecount2++;
audiobufferinfo.offset = offset;
audiobufferinfo.size = audioextractor.readsampledata(audiobuf, offset);
if (videobufferinfo.size < 0 || audiobufferinfo.size < 0) {
saweos2 = true;
audiobufferinfo.size = 0;
} else {
audiobufferinfo.presentationtimeus = audioextractor.getsampletime();
//noinspection wrongconstant
audiobufferinfo.flags = audioextractor.getsampleflags();
muxer.writesampledata(audiotrack, audiobuf, audiobufferinfo);
audioextractor.advance();
}
}
muxer.stop();
muxer.release();
logutil.d(tag,"output: "+outputfile);
} catch (ioexception e) {
logutil.d(tag, "mixer error 1 " + e.getmessage());
} catch (exception e) {
logutil.d(tag, "mixer error 2 " + e.getmessage());
}
}
方法三
利用mp4parser实现
mp4parser是一个视频处理的开源工具箱，由于mp4parser里的方法都依靠工具箱里的一些内容，所以需要将这些内容打包成jar包，放到自己的工程里，才能对mp4parser的方法进行调用。
compile “com.googlecode.mp4parser:isoparser:1.1.21”
问题：上传youtube压缩后，视频数据丢失严重，大部分就只剩下一秒钟的时长，相当于把视频变成图片了，囧
public boolean mux(string videofile, string audiofile, final string outputfile) {
if (isstopmux) {
return false;
}
movie video;
try {
video = moviecreator.build(videofile);
} catch (runtimeexception e) {
e.printstacktrace();
return false;
} catch (ioexception e) {
e.printstacktrace();
return false;
}
movie audio;
try {
audio = moviecreator.build(audiofile);
} catch (ioexception e) {
e.printstacktrace();
return false;
} catch (nullpointerexception e) {
e.printstacktrace();
return false;
}
track audiotrack = audio.gettracks().get(0);
video.addtrack(audiotrack);
container out = new defaultmp4builder().build(video);
fileoutputstream fos;
try {
fos = new fileoutputstream(outputfile);
} catch (filenotfoundexception e) {
e.printstacktrace();
return false;
}
bufferedwritablefilebytechannel bytebufferbytechannel = new
bufferedwritablefilebytechannel(fos);
try {
out.writecontainer(bytebufferbytechannel);
bytebufferbytechannel.close();
fos.close();
if (isstopmux) {
return false;
}
runonuithread(new runnable() {
@override
public void run() {
mcustomeprogressdialog.setprogress(100);
goshareactivity(outputfile);
// fileutils.insertmediadb(addaudiosactivity.this,outputfile);//
}
});
} catch (ioexception e) {
e.printstacktrace();
if (mcustomeprogressdialog.isshowing()) {
mcustomeprogressdialog.dismiss();
}
toastutil.showshort(getstring(r.string.process_failed));
return false;
}
return true;
}
private static class bufferedwritablefilebytechannel implements writablebytechannel {
private static final int buffer_capacity = 2000000;
private boolean isopen = true;
private final outputstream outputstream;
private final bytebuffer bytebuffer;
private final byte[] rawbuffer = new byte[buffer_capacity];
private bufferedwritablefilebytechannel(outputstream outputstream) {
this.outputstream = outputstream;
this.bytebuffer = bytebuffer.wrap(rawbuffer);
}
@override
public int write(bytebuffer inputbuffer) throws ioexception {
int inputbytes = inputbuffer.remaining();
if (inputbytes > bytebuffer.remaining()) {
dumptofile();
bytebuffer.clear();
if (inputbytes > bytebuffer.remaining()) {
throw new bufferoverflowexception();
}
}
bytebuffer.put(inputbuffer);
return inputbytes;
}
@override
public boolean isopen() {
return isopen;
}
@override
public void close() throws ioexception {
dumptofile();
isopen = false;
}
private void dumptofile() {
try {
outputstream.write(rawbuffer, 0, bytebuffer.position());
} catch (ioexception e) {
throw new runtimeexception(e);
}
}
}
方法四
利用ffmpeg大法
ffmpeg 由于其丰富的 codec 插件，详细的文档说明，并且与其调试复杂量大的编解码代码(是的，用 mediacodec 实现起来十分啰嗦和繁琐)还是不如调试一行 ffmpeg 命令来的简单。
merge video /audio and retain both audios
可以实现，兼容性强，但由于是软解码，合并速度很慢，忍受不了，而相应的ffmpeg优化还不太了解，囧…….
总结
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