'key' frame only decoding

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|

'key' frame only decoding

rohit khali
Hi All,


I want to integrate FFMPEG shared libraries in my 'key/I' frames
only' decoder application.

Will it be possible to limit decoding to I frames only for various video
codecs (MPEG-2, AVC and HEVC) without modifying FFMPEG code?



As part of initial checks, I came across below command, which seems to be
working however was wondering why '-vsync 0' parameter is needed.

./ffmpeg -skip_frame nokey -i .input.ts -vsync 0 output.yuv


Also in context of HEVC, does "key" frame in above command refer to all 3
IRAP types IDR, CRA, BLA ?


Thanks,

Rohit Khali
_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|

Re: 'key' frame only decoding

Nicolas George
rohit khali (12020-06-01):
> As part of initial checks, I came across below command, which seems to be
> working however was wondering why '-vsync 0' parameter is needed.

The output format you are using does not support timestamps, and
therefore must be used with constant frame rate, but keyframes are not
guaranteed to be constant frame rate. Therefore, ffmpeg will duplicate
frame as needed to meet the constant frame rate, by default the same as
the input.

-vsync 0 disables that: it tells ffmpeg to not bother about timestamps.

Regards,

--
  Nicolas George

_______________________________________________
ffmpeg-user mailing list
[hidden email]
https://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".

signature.asc (849 bytes) Download Attachment