[x264-devel] Reconfiguring x264 aspect ratio in the middle of stream

Gabriel Bouvigne gabriel.bouvigne at joost.com
Mon Jan 12 10:45:34 CET 2009

Jarmo Torvinen a écrit :

> 1) it is too time consuming to call the x264_encoder_reconfig() just for 
> the purpose 
> of changing the aspect ratio, I'd rather have separate API function which 
> just would do that. 
> But on the other hand, is there enough justification to add another api 
> call just for that purpose?

I don't think this would justify another API call

> 3) according to initial tests, the aspect ratio changes, but the timing is 
> not always correct. This is because the 
> aspect ratio info is sent in the SPS, so the timing depends on the timing 
> of the scene cut. To have correct timing, 
> there should be some way to force a scenecut or sending a SPS through the 
> API when the aspect ratio changes.

Yes, ideally you should have a way to force a new IDR.
However, I've seen many real DVB cases where the aspect ratio change was 
slightly delayed from its theoretical placement. This is often not a big 
issue, as TV broadcaster are often using short gops (about 15 to 30 frames).


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