[Ffmpeg-devel] b_quant_factor and B frames

Michael Niedermayer michaelni
Fri Sep 15 17:40:36 CEST 2006


On Fri, Sep 15, 2006 at 04:36:47PM +0200, Panagiotis Issaris wrote:
> Hi,
> In my removal of additional option from the OptionDef array, I noticed
> that the regression tests fail if I remove the b_quant_factor and use
> the AVOption one instead.
> While investigating why this was/is happening, I noticed that b_quant_factor
> always turned up as being 2.0 in my tracings.
> Now, apparently, in ffmpeg.c, the following lines occur:
>   3044         if (b_frames) {
>   3045             video_enc->max_b_frames = b_frames;
>   3046             video_enc->b_quant_factor = 2.0;
>   3047         }
> I had the impression b_quant_factor was only relevant when B-frames were
> used. If so, then it seems weird to me that it is always fixed at 2.0
> while there exists a commandline option to alter it.
> Any hints?

the code makes no sense, maybe it is from the time before b_quant_factor
could be specified on the cmd line
feel free to remove the if() and the b_quant_factor=2

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is

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