13.Android H265投屏

Android H265投屏

H265特点

• H265将宏块的大小从H264的16x16扩展到了64x64，以便于高分辨率视频的压缩
• H265采用了更加灵活的编码结构来提高编码效率
  包括编码单元（类似H264宏块，用于编码）、预测单元和变换单
• H265帧内预测
  • H265:所有的CU块，亮度有35种预测方向，色度5种
  • H264：亮度4x4和8x8块都是9个方向，16x16是4种方向，色度4种方向

H265码流分析

• H264的帧类型，因为H264是后5位保存帧类型数据，所以与1F即可

  图片.png

• H265的帧类型：将value&7E>>1就可以得到帧类型

  图片.png

图片.png

图片.png

以40 01为例

    0100  0000  40
&   0111  1110  7E
=   0100  0000  40
>>1 0010  0000  =32   //vps

42 01为例

    0100  0010  42
&   0111  1110  7E
=   0100  0010  42
>>1 0010  0001  =33   //sps

• 推送端

public void startLive() {
        try {
            //服务器端编码H264通过socket发送给客户端
            MediaFormat format = MediaFormat.createVideoFormat(MediaFormat.MIMETYPE_VIDEO_HEVC, mWidth, mHeight);
            format.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);
            format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 1);
            format.setInteger(KEY_BIT_RATE, mWidth * mHeight);
            format.setInteger(KEY_FRAME_RATE, 20);
            mMediaCodec = MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_VIDEO_HEVC);
            mMediaCodec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
            //创建场地
            Surface surface = mMediaCodec.createInputSurface();
            mVirtualDisplay = mMediaProjection.createVirtualDisplay("CodecLiveH265",
                    mWidth, mHeight, 1, DisplayManager.VIRTUAL_DISPLAY_FLAG_PUBLIC, surface, null, null);
            mHandler.post(this);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    @Override
    public void run() {
        mMediaCodec.start();
        MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
        while (true) {
            //取出数据发送给客户端
            int outIndex = mMediaCodec.dequeueOutputBuffer(bufferInfo, 1000);
            if (outIndex >= 0) {
                ByteBuffer buffer = mMediaCodec.getOutputBuffer(outIndex);
                dealFrame(buffer, bufferInfo);
                mMediaCodec.releaseOutputBuffer(outIndex, false);
            }
        }
    }

    public static final int NAL_I = 19;
    public static final int NAL_VPS = 32;
    //vps+sps+pps是一帧，所以只需要获取vps
    private byte[] vps_sps_pps_buffer;

    private void dealFrame(ByteBuffer buffer, MediaCodec.BufferInfo bufferInfo) {
        //过滤掉第一个0x00 00 00 01 或者0x 00 00 01
        int offset = 4;
        if (buffer.get(2) == 0x01) {
            offset = 3;
        }
        //获取帧类型
        int type = (buffer.get(offset) & 0x7E) >> 1;
        if (type == NAL_VPS) {
            vps_sps_pps_buffer = new byte[bufferInfo.size];
            buffer.get(vps_sps_pps_buffer);
        } else if (type == NAL_I) {
            //I帧
            final byte[] bytes = new byte[bufferInfo.size];
            buffer.get(bytes);
            //vps_pps_sps+I帧的数据
            byte[] newBuffer = new byte[vps_sps_pps_buffer.length + bytes.length];
            System.arraycopy(vps_sps_pps_buffer, 0, newBuffer, 0, vps_sps_pps_buffer.length);
            System.arraycopy(bytes, 0, newBuffer, vps_sps_pps_buffer.length, bytes.length);
            mWebSocketSendLive.sendData(newBuffer);
        }else{
            //P帧 B帧直接发送就可以了
            final byte[] bytes = new byte[bufferInfo.size];
            buffer.get(bytes);
            mWebSocketSendLive.sendData(bytes);
        }
    }

接收端

 //初始化解码器
    private fun initDecoder(surface: Surface?) {
        mMediaCodec = MediaCodec.createDecoderByType(MediaFormat.MIMETYPE_VIDEO_HEVC)
        val format =
            MediaFormat.createVideoFormat(MediaFormat.MIMETYPE_VIDEO_HEVC, mWidth, mHeight)
        format.setInteger(MediaFormat.KEY_BIT_RATE, mWidth * mHeight)
        format.setInteger(MediaFormat.KEY_FRAME_RATE, 20)
        format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 1)
        mMediaCodec.configure(
            format,
            surface,
            null, 0
        )
        mMediaCodec.start()
    }

override fun callBack(data: ByteArray?) {
        //回调
        LogUtils.e("接收到数据的长度:${data?.size}")
        //客户端主要将获取到的数据进行解码，首先需要通过dsp进行解码
        val index = mMediaCodec.dequeueInputBuffer(10000)
        if (index >= 0) {
            val inputBuffer = mMediaCodec.getInputBuffer(index)
            inputBuffer.clear()
            inputBuffer.put(data, 0, data!!.size)
            //通知dsp芯片帮忙解码
            mMediaCodec.queueInputBuffer(index, 0, data.size, System.currentTimeMillis(), 0)
        }
        //取出数据
        val bufferInfo = MediaCodec.BufferInfo()
        var outIndex: Int = mMediaCodec.dequeueOutputBuffer(bufferInfo, 10000)
        while (outIndex > 0) {
            mMediaCodec.releaseOutputBuffer(outIndex, true)
            outIndex = mMediaCodec.dequeueOutputBuffer(bufferInfo, 10000)
        }
    }