How to play raw h264 produced by MediaCodec encoder?

Question

I'm a bit new when it comes to MediaCodec (and video encoding/decoding in general), so correct me if anything I say here is wrong.

I want to play the raw h264 output of MediaCodec with VLC/ffplay. I need this to play becuase my end goal is to stream some live video to a computer, and MediaMuxer only produces a file on disk rather than something I can stream with (very) low latency to a desktop. (I'm open to other solutions, but I have not found anything else that fits the latency requirement)

Here is the code I'm using encode the video and write it to a file: (it's based off the MediaCodec example found here, only with the MediaMuxer part removed)

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));
            }
        }
    }
}

However, the file produced from this code does not play with VLC or ffplay. Can anyone tell me what I'm doing wrong? I believe it is due to an incorrect format (or total lack) of headers required for the playing of raw h264, as I have had success playing .264 files downloaded from the internet with ffplay. Also, I'm not sure exactly how I'm going to stream this video to a computer, so if somebody could give me some suggestions as to how I might do that, I would be very grateful! Thanks!

Answer 1

You should be able to play back a raw H264 stream (as you wrote, other raw .264 files play back just fine with VLC or ffplay), but you are missing the parameter sets. These are passed in two different ways, and you happen to be missing both. First they are returned in MediaFormat when you get MediaCodec.INFO_OUTPUT_FORMAT_CHANGED (which you don't handle, you just log a message about it), secondly they are returned in a buffer with MediaCodec.BUFFER_FLAG_CODEC_CONFIG set (which you ignore by setting the size to 0). The simplest solution here is to remove the special case handling of MediaCodec.BUFFER_FLAG_CODEC_CONFIG, and it should all work just fine.

The code you've based it on does things this way in order to test all the different ways of doing things - where you copied it from, the parameter sets were carried in the MediaFormat from MediaCodec.INFO_OUTPUT_FORMAT_CHANGED. If you wanted to use that in your case with a raw H264 bytestream, you could write the byte buffers with keys csd-0 and csd-1 from the MediaFormat and keep ignoring the buffers with MediaCodec.BUFFER_FLAG_CODEC_CONFIG set.

Answer 2

You cannot play just raw h264. It does not have any information about format. You also can find several great examples here. In order to stream you need to implement some streaming protocol like RTSP (in a case of real time streaming) or more flexible HLS (if real time is not required)