如果文件未正确完成，您如何使用 libav 编写可播放的 .mov 文件

Question

I'm developing a video recording application in c++ with the libav c library which records and encodes h265 from a camera feed into a .mov container.

I can successfully play back the .mov file on all standard video players, but only if the recording is terminated properly - ie calling av_write_trailer and properly closing the file.

One important requirements of the software, however, is a playable .mov file even in the event that the recording is terminated inappropriately - ie power loss or target disk becomes full.

I'm assuming this is possible as most video recording devices create valid .mov files even when they run out of battery or fill their target media.

I have tried specifying the following AVDictionary option which is suppose to move relevant stream information to the start of the file:

av_dict_set(&options, "movflags", "faststart", 0);

However, this does not make incomplete files playable.

Answer 1

I believe this is the options you're looking for:

av_dict_set(&options, "movflags", "+frag_keyframe+empty_moov+faststart", 0);

This is what is used for streaming mp4 , so the stream is both playable and interruptible at any time.

As a downside, such video file won't be seekable. But you can probably post-process such incomplete files and fix headers once the power is restored.