[FFmpeg-user] Mosaic issue when playing RMVB with ffmpeg

[Wang Xingchao]

Hi Community,

I met an weird issue on Mosaic when playing RMVB video files with ffmpeg.
It's 100% reproduced when seek forward/backward, the mosaic video
picture would last for ~4 seconds and recover back to normal playback.

The issue is reproduced with below environments:
- ffplay version 0.8
- android + ffmpeg 1.13
- play some particular rmvb files, not all rmvb files

please note this issue doesnot occur with ffplay 2.0 on desktop.

The audio codec type is "AAC" inside the rmvb test video file. The
only workround for me is to disable audio with "-an" option, this will
remove mosaic, and that's why i feel so weird.

Here's the log message i met when playing the video with "ffplay", you
can see audio decoding fails:
"[aac @ 0x7fe188000e20] channel element 0.0 is not allocated=0/2   f=0/0
[aac @ 0x7fe188000e20] SBR was found before the first channel element.
[aac @ 0x7fe188000e20] channel element 0.13 is not allocated
[aac @ 0x7fe188000e20] SBR was found before the first channel element.
[aac @ 0x7fe188000e20] channel element 2.14 is not allocated
[aac @ 0x7fe188000e20] channel element 2.12 is not allocated
[rv40 @ 0x7fe188003260] First slice header is incorrect, ret=0, si.start 960
[rv40 @ 0x7fe188003260] Invalid decoder state: B-frame without reference data.
[rv40 @ 0x7fe188003260] warning: first frame is no keyframe
[aac @ 0x7fe188000e20] channel element 0.0 is not allocated=0/42
"
Seems the audio packet damaged before sending to decoder, but how does
that has impact on video playback?

Another clue is about av_seek_frame(), it may seek to wrong positioin
with audio enabled, that make video packets damaged too, but i'm not
sure about that.

I need more guide on such mosaic issue, any comments would be appreciated.

thanks
--xingchao