实时 RTSP 流解码：在 Android 上使用 MediaPlayer 时视频延迟较大

发布于 2024-12-27 19:59:40 字数 1435 浏览 2 评论 0原文

我正在从 PC 上的 VLC 播放 Live RTSP 流到 Android MediaPlayer 类（两者都在同一本地网络上）。它播放流畅，没有错误 - 问题是屏幕上的解码视频比实时视频晚大约 5 到 7 秒。

从调试和回调中我可以看到实时数据到达设备<启动mMediaPlayer.prepareAsync()后1秒。此时 MediaPlayer 类开始计算流的格式、尺寸等。然后，在视频显示在屏幕上之前（5 到 7 秒后），将调用 onPrepared()，其中我调用mMediaPlayer.start()。看起来这个 start() 播放了最初从准备阶段开始捕获的视频。

我在 start() 之前和之后都尝试过 seekTo(5000)，但它对延迟完全没有影响。

对于实时视频通话应用程序来说，几秒钟的设置延迟是完全可以的，但视频呈现后的这种延迟对我来说是无法接受的。

public void surfaceCreated(SurfaceHolder holder)
{
   mMediaPlayer = new MediaPlayer();
   mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
   mMediaPlayer.setOnInfoListener(this);
   mMediaPlayer.setOnErrorListener(this);
   mMediaPlayer.setOnVideoSizeChangedListener(this);
   mMediaPlayer.setOnBufferingUpdateListener(this);
   mMediaPlayer.setDataSource("rtsp://192.168.1.4:5544/test");
   mMediaPlayer.setDisplay(holder);
   mMediaPlayer.setScreenOnWhilePlaying(true);
   mMediaPlayer.setOnPreparedListener(this);
   mMediaPlayer.setOnCompletionListener(this);
   mMediaPlayer.prepareAsync();
   ...
public void onPrepared(MediaPlayer mediaplayer)
{
   mMediaPlayer.start();
...

有什么想法可以减少这种延迟，或者寻求 MediaPlayer 缓冲的内容的结尾吗？我的设备是3.1，minSdkVersion是2.2。

编辑：

我在 AwesomePlayer.cpp 中发现了一些高水位线和低水位线（2s 和 8s）。作为一个快速测试，我破解了 libstagefright.so 来制作这些 0.1 和 1。但这对延迟没有影响。我的搜索仍在继续...

原文

I'm playing a Live RTSP stream from VLC on a PC to Android MediaPlayer class (both on same local network). It plays smoothly with no errors - the problem is that the decoded video on screen is between around 5 and 7 seconds behind live.

From debug and callbacks I can see that the live data is arriving on the device < 1s after starting mMediaPlayer.prepareAsync(). This is when the MediaPlayer class begins to work out what format the stream is with what dimensions etc. Then just before video is shown on screen (between 5 and 7 seconds later), onPrepared() is called where I call mMediaPlayer.start(). It looks like this start() plays the video that was originally captured from the start of the prepare stage.

I've tried seekTo(5000) both before and after start(), but it has no effect on the lag at all.

For a live video calling app, the setup delay of a few seconds is perfectly fine, but this lag once video is presented is unaccaptable to me.

public void surfaceCreated(SurfaceHolder holder)
{
   mMediaPlayer = new MediaPlayer();
   mMediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
   mMediaPlayer.setOnInfoListener(this);
   mMediaPlayer.setOnErrorListener(this);
   mMediaPlayer.setOnVideoSizeChangedListener(this);
   mMediaPlayer.setOnBufferingUpdateListener(this);
   mMediaPlayer.setDataSource("rtsp://192.168.1.4:5544/test");
   mMediaPlayer.setDisplay(holder);
   mMediaPlayer.setScreenOnWhilePlaying(true);
   mMediaPlayer.setOnPreparedListener(this);
   mMediaPlayer.setOnCompletionListener(this);
   mMediaPlayer.prepareAsync();
   ...
public void onPrepared(MediaPlayer mediaplayer)
{
   mMediaPlayer.start();
...

Any ideas how I can reduce this lag, or seek to the end of what is buffered by MediaPlayer? My device is 3.1, minSdkVersion is 2.2.

EDIT:

I've found some high and low water-marks in AwesomePlayer.cpp (2s and 8s). As a quick test I have hacked the libstagefright.so to make these 0.1s and 1s. This however made no effect on the delay. My search continues...

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云柯 2025-01-03 19:59:40

我不会给出最终答案，但让我分享一下我现在所拥有的。

我在 PC 上本地播放时遇到了 5 秒延迟的问题，从 GStreamer 到 GStreamer。将以下参数添加到管道后，延迟消失了：
- 在客户端 - rtspsrc 的 latency=0 参数；
- 在服务器上 - v4l2src 的 is-live=1 参数，当然还有 x264enc tune=zerolatency。

无法控制 MediaPlayer/VideoView 的编解码器/媒体源参数。据我所知，MediaCodec API 中都没有。

所以我们需要使用 GStreamer 或 ffmpeg。