[x264-devel] Re: [PATCH] Forcing frame coding as IDR

[Jingyi Hu]

1) I think if every scenecut detection you use a IDR, it will cost more than 
use other methods (like I-Blocks),  all reference data are lost! Really it 
depend coding trade-off.

2) Think about  a live content feed system, everything is automatic.

4) You talk about  a perfect world with fix fps. How about other conditions?

Thanks.

Jingyi Hu



>From: Loren Merritt <lorenm at u.washington.edu>
>Reply-To: x264-devel at videolan.org
>To: x264-devel at videolan.org
>Subject: [x264-devel] Re: [PATCH] Forcing frame coding as IDR
>Date: Mon, 4 Jun 2007 23:57:03 -0600 (MDT)
>
>On Mon, 4 Jun 2007, Jingyi Hu wrote:
>
>>It all depend on the clips and output frame location:
>>1)If all clips contents are not all related, the separate encoding will 
>>make more efficient in coding mv search, reference frame search etc.
>
>If clips contents are not related, then x264's scenecut detection will 
>trigger and put a keyframe there anyway. The purpose of forcing keyframes 
>is if the chapter break occurs somewhere that's not an obvious scenecut. 
>e.g. frade to black, chapter break, fade in next scene.
>
>>2)If you do not have a IDR interval parameter setting and clips scene 
>>changes a little, you will not have a IDR for a while. In this case, it 
>>will big offset between IDR and require frame #.
>
>Say in english please?
>
>>3)Usually end user do not have accurate idea about exact frame #. If you 
>>force set the frame # become IDR, it will increase stream data overhead.
>
>If the user doesn't know the exact frame numbers, how is he supposed to 
>split the video either? And if you want some algorithm to find scenecuts, 
>what's wrong with the current one?
>
>>4)The best approach to give the time duration or output bitstream size. 
>>Let program determine which frame numbers are and carry the extract 
>>output.
>
>How does time duration differ from frame number? Just multiply by fps.
>And splitting by output bitstream size is a completely different goal.
>
>
>P.S. please don't top-post, and please don't break threading.
>
>--Loren Merritt
>
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>This is the x264-devel mailing-list
>To unsubscribe, go to: http://developers.videolan.org/lists.html
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