[Libav-user] Closed GOP structure problem

NITIN GOYAL nitinkumgoyal at gmail.com
Thu Jan 1 06:12:13 CET 2015

It looks odd coz as per my understanding GOP with B frames generally ends
with B frames and not P frame as you are getting. Can yu check if its open
GOP or closed GOP or if you are missing to get the last B frames while

On Fri, Dec 19, 2014 at 8:38 PM, Valentin Noël <van at mikrosimage.eu> wrote:

> Hi to all,
> I would like to encode MPEG-2 video with closed GOP of 12 frames, and a
> structure like IBBPBBPBBPBB.
> For doing this, I am using these options :
> *-g 12* to set the GOP size
> *-bf 2* to set the max B frames between reference frames
> *-flags +cgop* to use Closed GOP
> *-sc_threshold 1000000000* to disable scene change detection
> However, the result is a GOP of 10 frames IBBPBBPBBP, with two missing B
> frames.
> How can I do to fix this ? Is there something missing ?
> It seems that a "strict_gop" parameter (or "sgop" flag) used to exist in
> former versions of ffmpe to enforce GOP size. Is there an equivalent
> nowadays ?
> Thanks.
> Valentin
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