使用Android的MediaCodec + mp4parser编码时，什么决定播放速度? [英] What governs playback speed when encoding with Android's MediaCodec + mp4parser?

问题描述

我正在尝试结合MediaCodec和Mp4Parser(封装为.mp4)在Android上使用API​​ 16录制，编码并最终制作一部短片.

I'm trying to record, encode and finally create a short movie on Android (using API 16) with a combination of MediaCodec and Mp4Parser (to encapsulate into .mp4).

除了.mp4的持续时间外，一切正常，它始终为3秒，运行速度约为正确"速度的两倍.

Everything is working just fine, except for the duration of the .mp4: its always 3 seconds long - and runs at about twice the 'right' speed.

• 编码器的输入为84帧(相隔100ms).
• 最后一帧设置流结束"标志.
• 我在queueInputBuffer
上设置每帧的演示时间

• The input to encoder is 84 frames (taken 100ms apart).
• The last frame sets the 'end of stream' flag.
• I set the presentation time for each frame on queueInputBuffer

我试图调整所有可能的参数-但似乎没有什么不同-电影总是3秒长-总是播放得太快了.

I've tried to tweak every conceivable parameter - but nothing seems to make a difference - the film is always 3 seconds long - and always played way too fast.

那么什么决定了播放的渗透呢?如何以"natuarl"速度拍摄电影?

So what governs the playback seepd? how do I generate a film with 'natuarl' speed?

推荐答案

我知道了:用mp4parser封装时(如果目标API是18)，则需要在mp4parser的API中设置速度.如果您未使用Android的内置混合器(仅可从API18获得)，则您提供给queueInputBuffer的演示时间似乎没有任何区别.

I figured it out: When encapsulating with mp4parser (needed if you target API<18), you need to set the speed in mp4parser's API. The presentation time you provide to queueInputBuffer appearently make no difference if you're not using Android's built-in muxer (available only from API18).

我在github上偶然发现了这个问题，该问题表明需要以下内容:

I stumbled on this question on github, which indicates the following is required:

 new H264TrackImpl(new FileDataSourceImpl(rawDataFile), "eng", 100, 10);

• 最后两个参数(timeScale和frameTick)将播放速度设置为"noraml".

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