对于MediaCodec（以及一般的视频编码/解码），我有点新意，所以如果我在这里说的任何内容都是错误的，请纠正我。
我想用VLC / ffplay播放MediaCodec的原始h264输出。我需要这个才能发挥，因为我的最终目标是将一些实时视频流式传输到计算机，而MediaMuxer只在磁盘上生成一个文件，而不是我可以以非常低的延迟流式传输到桌面。 （我对其他解决方案持开放态度，但我还没有找到符合延迟要求的其他解决方案）
以下代码我使用对视频进行编码并将其写入文件:(它基于找到的MediaCodec示例here，仅删除了MediaMuxer部分）
package com.jackos2500.droidtop;
import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaFormat;
import android.opengl.EGL14;
import android.opengl.EGLConfig;
import android.opengl.EGLContext;
import android.opengl.EGLDisplay;
import android.opengl.EGLExt;
import android.opengl.EGLSurface;
import android.opengl.GLES20;
import android.os.Environment;
import android.util.Log;
import android.view.Surface;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
public class StreamH264 {
private static final String TAG = "StreamH264";
private static final boolean VERBOSE = true; // lots of logging
// where to put the output file (note: /sdcard requires WRITE_EXTERNAL_STORAGE permission)
private static final File OUTPUT_DIR = Environment.getExternalStorageDirectory();
public static int MEGABIT = 1000 * 1000;
private static final int IFRAME_INTERVAL = 10;
private static final int TEST_R0 = 0;
private static final int TEST_G0 = 136;
private static final int TEST_B0 = 0;
private static final int TEST_R1 = 236;
private static final int TEST_G1 = 50;
private static final int TEST_B1 = 186;
private MediaCodec codec;
private CodecInputSurface inputSurface;
private BufferedOutputStream out;
private MediaCodec.BufferInfo bufferInfo;
public StreamH264() {
}
private void prepareEncoder() throws IOException {
bufferInfo = new MediaCodec.BufferInfo();
MediaFormat format = MediaFormat.createVideoFormat("video/avc", 1280, 720);
format.setInteger(MediaFormat.KEY_BIT_RATE, 2 * MEGABIT);
format.setInteger(MediaFormat.KEY_FRAME_RATE, 30);
format.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);
format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, IFRAME_INTERVAL);
codec = MediaCodec.createEncoderByType("video/avc");
codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
inputSurface = new CodecInputSurface(codec.createInputSurface());
codec.start();
File dst = new File(OUTPUT_DIR, "test.264");
out = new BufferedOutputStream(new FileOutputStream(dst));
}
private void releaseEncoder() throws IOException {
if (VERBOSE) Log.d(TAG, "releasing encoder objects");
if (codec != null) {
codec.stop();
codec.release();
codec = null;
}
if (inputSurface != null) {
inputSurface.release();
inputSurface = null;
}
if (out != null) {
out.flush();
out.close();
out = null;
}
}
public void stream() throws IOException {
try {
prepareEncoder();
inputSurface.makeCurrent();
for (int i = 0; i < (30 * 5); i++) {
// Feed any pending encoder output into the file.
drainEncoder(false);
// Generate a new frame of input.
generateSurfaceFrame(i);
inputSurface.setPresentationTime(computePresentationTimeNsec(i, 30));
// Submit it to the encoder. The eglSwapBuffers call will block if the input
// is full, which would be bad if it stayed full until we dequeued an output
// buffer (which we can't do, since we're stuck here). So long as we fully drain
// the encoder before supplying additional input, the system guarantees that we
// can supply another frame without blocking.
if (VERBOSE) Log.d(TAG, "sending frame " + i + " to encoder");
inputSurface.swapBuffers();
}
// send end-of-stream to encoder, and drain remaining output
drainEncoder(true);
} finally {
// release encoder, muxer, and input Surface
releaseEncoder();
}
}
private void drainEncoder(boolean endOfStream) throws IOException {
final int TIMEOUT_USEC = 10000;
if (VERBOSE) Log.d(TAG, "drainEncoder(" + endOfStream + ")");
if (endOfStream) {
if (VERBOSE) Log.d(TAG, "sending EOS to encoder");
codec.signalEndOfInputStream();
}
ByteBuffer[] outputBuffers = codec.getOutputBuffers();
while (true) {
int encoderStatus = codec.dequeueOutputBuffer(bufferInfo, TIMEOUT_USEC);
if (encoderStatus == MediaCodec.INFO_TRY_AGAIN_LATER) {
// no output available yet
if (!endOfStream) {
break; // out of while
} else {
if (VERBOSE) Log.d(TAG, "no output available, spinning to await EOS");
}
} else if (encoderStatus == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
// not expected for an encoder
outputBuffers = codec.getOutputBuffers();
} else if (encoderStatus == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
// should happen before receiving buffers, and should only happen once
MediaFormat newFormat = codec.getOutputFormat();
Log.d(TAG, "encoder output format changed: " + newFormat);
} else if (encoderStatus < 0) {
Log.w(TAG, "unexpected result from encoder.dequeueOutputBuffer: " + encoderStatus);
// let's ignore it
} else {
ByteBuffer encodedData = outputBuffers[encoderStatus];
if (encodedData == null) {
throw new RuntimeException("encoderOutputBuffer " + encoderStatus + " was null");
}
if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_CODEC_CONFIG) != 0) {
// The codec config data was pulled out and fed to the muxer when we got
// the INFO_OUTPUT_FORMAT_CHANGED status. Ignore it.
if (VERBOSE) Log.d(TAG, "ignoring BUFFER_FLAG_CODEC_CONFIG");
bufferInfo.size = 0;
}
if (bufferInfo.size != 0) {
// adjust the ByteBuffer values to match BufferInfo (not needed?)
encodedData.position(bufferInfo.offset);
encodedData.limit(bufferInfo.offset + bufferInfo.size);
byte[] data = new byte[bufferInfo.size];
encodedData.get(data);
out.write(data);
if (VERBOSE) Log.d(TAG, "sent " + bufferInfo.size + " bytes to file");
}
codec.releaseOutputBuffer(encoderStatus, false);
if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
if (!endOfStream) {
Log.w(TAG, "reached end of stream unexpectedly");
} else {
if (VERBOSE) Log.d(TAG, "end of stream reached");
}
break; // out of while
}
}
}
}
private void generateSurfaceFrame(int frameIndex) {
frameIndex %= 8;
int startX, startY;
if (frameIndex < 4) {
// (0,0) is bottom-left in GL
startX = frameIndex * (1280 / 4);
startY = 720 / 2;
} else {
startX = (7 - frameIndex) * (1280 / 4);
startY = 0;
}
GLES20.glClearColor(TEST_R0 / 255.0f, TEST_G0 / 255.0f, TEST_B0 / 255.0f, 1.0f);
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
GLES20.glEnable(GLES20.GL_SCISSOR_TEST);
GLES20.glScissor(startX, startY, 1280 / 4, 720 / 2);
GLES20.glClearColor(TEST_R1 / 255.0f, TEST_G1 / 255.0f, TEST_B1 / 255.0f, 1.0f);
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
GLES20.glDisable(GLES20.GL_SCISSOR_TEST);
}
private static long computePresentationTimeNsec(int frameIndex, int frameRate) {
final long ONE_BILLION = 1000000000;
return frameIndex * ONE_BILLION / frameRate;
}
/**
* Holds state associated with a Surface used for MediaCodec encoder input.
* <p>
* The constructor takes a Surface obtained from MediaCodec.createInputSurface(), and uses that
* to create an EGL window surface. Calls to eglSwapBuffers() cause a frame of data to be sent
* to the video encoder.
* <p>
* This object owns the Surface -- releasing this will release the Surface too.
*/
private static class CodecInputSurface {
private static final int EGL_RECORDABLE_ANDROID = 0x3142;
private EGLDisplay mEGLDisplay = EGL14.EGL_NO_DISPLAY;
private EGLContext mEGLContext = EGL14.EGL_NO_CONTEXT;
private EGLSurface mEGLSurface = EGL14.EGL_NO_SURFACE;
private Surface mSurface;
/**
* Creates a CodecInputSurface from a Surface.
*/
public CodecInputSurface(Surface surface) {
if (surface == null) {
throw new NullPointerException();
}
mSurface = surface;
eglSetup();
}
/**
* Prepares EGL. We want a GLES 2.0 context and a surface that supports recording.
*/
private void eglSetup() {
mEGLDisplay = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY);
if (mEGLDisplay == EGL14.EGL_NO_DISPLAY) {
throw new RuntimeException("unable to get EGL14 display");
}
int[] version = new int[2];
if (!EGL14.eglInitialize(mEGLDisplay, version, 0, version, 1)) {
throw new RuntimeException("unable to initialize EGL14");
}
// Configure EGL for recording and OpenGL ES 2.0.
int[] attribList = {
EGL14.EGL_RED_SIZE, 8,
EGL14.EGL_GREEN_SIZE, 8,
EGL14.EGL_BLUE_SIZE, 8,
EGL14.EGL_ALPHA_SIZE, 8,
EGL14.EGL_RENDERABLE_TYPE, EGL14.EGL_OPENGL_ES2_BIT,
EGL_RECORDABLE_ANDROID, 1,
EGL14.EGL_NONE
};
EGLConfig[] configs = new EGLConfig[1];
int[] numConfigs = new int[1];
EGL14.eglChooseConfig(mEGLDisplay, attribList, 0, configs, 0, configs.length,
numConfigs, 0);
checkEglError("eglCreateContext RGB888+recordable ES2");
// Configure context for OpenGL ES 2.0.
int[] attrib_list = {
EGL14.EGL_CONTEXT_CLIENT_VERSION, 2,
EGL14.EGL_NONE
};
mEGLContext = EGL14.eglCreateContext(mEGLDisplay, configs[0], EGL14.EGL_NO_CONTEXT,
attrib_list, 0);
checkEglError("eglCreateContext");
// Create a window surface, and attach it to the Surface we received.
int[] surfaceAttribs = {
EGL14.EGL_NONE
};
mEGLSurface = EGL14.eglCreateWindowSurface(mEGLDisplay, configs[0], mSurface,
surfaceAttribs, 0);
checkEglError("eglCreateWindowSurface");
}
/**
* Discards all resources held by this class, notably the EGL context. Also releases the
* Surface that was passed to our constructor.
*/
public void release() {
if (mEGLDisplay != EGL14.EGL_NO_DISPLAY) {
EGL14.eglMakeCurrent(mEGLDisplay, EGL14.EGL_NO_SURFACE, EGL14.EGL_NO_SURFACE,
EGL14.EGL_NO_CONTEXT);
EGL14.eglDestroySurface(mEGLDisplay, mEGLSurface);
EGL14.eglDestroyContext(mEGLDisplay, mEGLContext);
EGL14.eglReleaseThread();
EGL14.eglTerminate(mEGLDisplay);
}
mSurface.release();
mEGLDisplay = EGL14.EGL_NO_DISPLAY;
mEGLContext = EGL14.EGL_NO_CONTEXT;
mEGLSurface = EGL14.EGL_NO_SURFACE;
mSurface = null;
}
/**
* Makes our EGL context and surface current.
*/
public void makeCurrent() {
EGL14.eglMakeCurrent(mEGLDisplay, mEGLSurface, mEGLSurface, mEGLContext);
checkEglError("eglMakeCurrent");
}
/**
* Calls eglSwapBuffers. Use this to "publish" the current frame.
*/
public boolean swapBuffers() {
boolean result = EGL14.eglSwapBuffers(mEGLDisplay, mEGLSurface);
checkEglError("eglSwapBuffers");
return result;
}
/**
* Sends the presentation time stamp to EGL. Time is expressed in nanoseconds.
*/
public void setPresentationTime(long nsecs) {
EGLExt.eglPresentationTimeANDROID(mEGLDisplay, mEGLSurface, nsecs);
checkEglError("eglPresentationTimeANDROID");
}
/**
* Checks for EGL errors. Throws an exception if one is found.
*/
private void checkEglError(String msg) {
int error;
if ((error = EGL14.eglGetError()) != EGL14.EGL_SUCCESS) {
throw new RuntimeException(msg + ": EGL error: 0x" + Integer.toHexString(error));
}
}
}
}
但是，从此代码生成的文件不能与VLC或ffplay一起使用。谁能告诉我我做错了什么？我认为这是因为播放原始h264所需的标题格式（或完全缺乏）不正确，因为我已经成功播放了使用ffplay从互联网上下载的.264文件。此外，我不确定我将如何将此视频流式传输到计算机上，所以如果有人能就我如何做到这一点给我一些建议，我将非常感激！谢谢！
答案 0 :(得分：7)
您应该能够播放原始H264流（正如您所写，其他原始.264文件可以使用VLC或ffplay进行回放），但您缺少参数集。这些是以两种不同的方式传递的，而你碰巧两者都错过了。首先，当你得到MediaFormat（你没有处理，你只是记录一条关于它的消息）时，它们会在MediaCodec.INFO_OUTPUT_FORMAT_CHANGED中返回，其次它们会在设置了MediaCodec.BUFFER_FLAG_CODEC_CONFIG的缓冲区中返回（通过将大小设置为0来忽略它。这里最简单的解决方案是删除MediaCodec.BUFFER_FLAG_CODEC_CONFIG的特殊情况处理，它应该都可以正常工作。
你基于它的代码以这种方式做事，以便测试所有不同的做事方式 - 你从中复制它，参数集是在MediaFormat MediaCodec.INFO_OUTPUT_FORMAT_CHANGED中进行的}。如果您希望在原始H264字节流的情况下使用它，您可以使用csd-0中的密钥csd-1和MediaFormat编写字节缓冲区，并使用{{1}忽略缓冲区设置。
答案 1 :(得分：1)
你不能只玩原始的h264。它没有关于格式的任何信息。您还可以找到几个很好的例子here。为了流式传输，您需要实现一些流媒体协议，如RTSP（在实时流媒体的情况下）或更灵活的HLS（如果不需要实时）