[FFmpeg-devel] Accessing compressed domain data

[guido manfredi]

Thanks for replying.

At which level am I supposed to add this "if" statement ?
Moreover, if I later want to retrieve P-frames too, won't this be a probleme
?

Guido


2009/10/22 Michael Niedermayer <michaelni at gmx.at>

> On Thu, Oct 22, 2009 at 04:58:58PM -0400, guido manfredi wrote:
> > Hi,
> >
> > I'm running a research project using H.264 video codec.
> > I would like to use ffmpeg in order to retrieve frames ( I-frames
> especially
> > ) in compressed domain.
> > My goal is to get the DCT coefficients of each I-frame, with only partial
> > decoding of the frame.
> >
> > Is there a way to stop frame decoding before IDCT, so i can retrieve DCT
> > coefficients and btw save computation time ?
> >
> > I suppose i should change some lines in h264.c : hl_decode_mb_internal(),
> is
> > that right ?
>
> the clean way to do this is with
>
> if(s->avctx->debug&FF_DEBUG_DCT_COEFF){
>    copy coeffs -> picture.dct_coeff[]
> }
>
> such a patch might be accepted if it causes no meassureable slowdown!
>
>
> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> The worst form of inequality is to try to make unequal things equal.
> -- Aristotle
>
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