[Libav-user] ffmpeg fragmentation
simone.cilli at spark-security.com
Wed Feb 18 10:56:52 CET 2015
I'm trying to create a fragmented mp4 recording using ffmpeg API. I'm running on an ARM Linux system. I have two main purposes:
* Avoid corrupted recordings in case of system crash;
* Allow user to play file while recording.
Reading ffmpeg documentation (https://www.ffmpeg.org/ffmpeg-formats.html#mov_002c-mp4_002c-ismv) I used different combinations of these flags:
* movflags frag_keyframe
* movflags empty_moov
The result is always the follow:
1. I start the recording;
2. A file is created in the output directory with size 28 B;
3. The size is kept until the end of the recording;
4. I stop the recording;
5. The file size increases until to reach the final size;
6. The file could be read with ffplay and/or VLC.
If I shutdown the system while recording, the video is a 28 B file not playable. It seems ffmpeg keeps in memory the recording until the stop and only then it writes in file system.
Using frag_keyframe and min_frag_duration in Windows I see the file increase its size while recording.
What is the common behavior of ffmpeg fragmentation? Is file "buffering" expected? Can I activate some flag to flush the file periodically?
Any idea to achieve my two goals?
Thanks in advance,
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