[x264-devel] Re: Using I-frame instead of IDR

[Loren Merritt]

On Wed, 15 Nov 2006, Axel Gunter wrote:
> Loren Merritt wrote:
>> On Wed, 15 Nov 2006, Axel Gunter wrote:
>> 
>>> I noticed all the I-frames introduced by the x264 code were IDR Access 
>>> Units. Is there a way I can have non-IDR I-frames in x264 encoding?
>> 
>> No. Why do you want non-IDR I-frames? The only reason I can think of is 
>> open-GOP B-frames, which x264 also doesn't do.
>
> I guess the compression would be better if the frames following the IDR or 
> I-picture could use frames temporally before the IDR/I-picture since they 
> have more reference frames to chose from. Since IDR forces a decoder 
> reference buffer flush, this isn't possible. Correct me if I am wrong.

In that case, look at --min-keyint. If a scenecut is too close to the 
previous IDR (default: 25 frames) it gets encoded as a non-IDR I-frame. 
Note that this is not optimal, but the metric that would really optimize 
for compression ratio isn't possible to measure in 1 pass, and I haven't 
written a 2 pass scenecut/IDR algorithm yet.

--Loren Merritt

-- 
This is the x264-devel mailing-list
To unsubscribe, go to: http://developers.videolan.org/lists.html