[FFmpeg-user] FFmpeg XDCAMHD422 streamcopy ClosedGOP problem

[Christoph Gerstbauer]

Hello Carl,

good hint.

But I have made some tests. And this raises another question:

A conventional Start of an XDCAMHD422 file has this GOP structure (closed):

B.B.I.B.B.P.B.B.P.B.B.P.B.B.I......



After FFMpeg has cut out a clip, because FFmpeg always cuts at I_frames 
(doesn matter which -ss position I give, it always cuts at the nearest 
I_frame):

I.B.B.P.B.B.P.B.B.P.B.B.I......

Is it possible to force FFmpeg to cut 2 frames BEFORE an I-Frame 
(streamcopy)?
To get a cutout file with the first GOP structure like this: 
B.B.I.B.B.P.B.B.P.B.B.P.B.B.I......

Is there a syntax to do so?

Best Regards

Christoph


Am 22.06.16 um 15:22 schrieb Carl Eugen Hoyos:
> Christoph Gerstbauer <christophgerstbauer <at> gmail.com> writes:
>
>> So my need is to force FFMpeg to make an extraction via codec
>> copy (copy video and audiostreams) , BUT JUST ENCODE the first
>> GOP to a new CLOSED GOP.
> Then you either have to program an application (that uses
> FFmpeg libraries if you want) or run ffmpeg (the application)
> several times to reencode a part and stream copy another part
> and concatenate.
> This may or may not lead to sync issues;-(
>
> Carl Eugen
>
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