Re: Dump raw compressed video -dumpvideo

From: "Carl Eugen Hoyos"
To: "MPlayer usage questions, feature requests, bug reports" 
<[email protected]>
Sent: Wednesday, March 14, 2018 1:48 AM
Subject: Re: [MPlayer-users] Dump raw compressed video -dumpvideo


> 2018-03-12 8:28 GMT+01:00, Bill Crockett

>> mplayer -dumpvideo some_video.mpg
>>
>> Dump raw compressed video stream to stream.dump
>
>> To see these raw videos, I would use something like this:
>>
>> mplayer -demuxer rawvideo -rawvideo fps=23.976:w=1280:h=720 stream.dump
>>
>> mplayer -demuxer rawvideo -rawvideo
>> fps=23.976:w=1280:h=720:format=i420:size=1382400 stream.dump
>
> These command lines are not supposed to support "raw compressed
> video" (but only raw uncompressed video), they should work with:
> $ mplayer stream.dump
>
>> This seems to work with mpeg videos and 1 or 2 other formats, but is not
>> working with an mp4 video with the x264 codec.
>
> The needed extradata is missing when dumping the video stream from mp4
> with -dumpvideo. You cannot easily fix this.
> One alternative is to use ffmpeg for this use-case:
> $ ffmpeg -i input.mp4 -vcodec copy dump.h264
>
> Carl Eugen

Thanks for your info on this.

Unfortunately, the FFmpeg dump.h264 produced the same results as MPlayer.  I 
even tried ffplay -f rawvideo -pixel_format yuv420p -video_size 
1280x720 -framerate 23.976 dump.h264.    Nothing but static on the screen.

> These command lines are not supposed to support "raw compressed
> video" (but only raw uncompressed video)

I think you are right, and that the -dumpvideo command is ripping too much 
of the header in mp4 or mov files encoded with x264 avc making it impossible 
to play.

I have spent too much time on this and will move on. 


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