[FFmpeg-devel] [PATCH] ffmpeg2theora 6to2channel-resample.patch

[Michael Niedermayer]

On Sun, May 01, 2011 at 07:50:47PM +0200, Reimar Döffinger wrote:
> Just some quick comments
> 
> On Sun, May 01, 2011 at 07:38:27PM +0200, Michael Niedermayer wrote:
> > +/*
> > +*/
> > +static short clip_short(int v) {
> > +    if (v < -32768)
> > +        v = -32768;
> > +    else if (v > 32767)
> > +        v = 32767;
> > +    return (short) v;
> > +}
> 
> Looks like a bad reimplementation of av_clip_int16,
> and generally "short" shouldn't be used but that's
> already in existing code...
> 
> >      for(i=0;i<n;i++) {
> > -        *output1++ = *input++;
> > -        *output2++ = *input++;
> > +        if (channels == 2) {
> > +            /* simple stereo to stereo. Input is: l, r */
> > +            l = input[0];
> > +            r = input[1];
> > +        } else if (channels == 6) {
> > +            /* 5.1 to stereo input: [fl, fr, c, lfe, rl, rr] */
> > +            int fl,fr,c,rl,rr,lfe;
> > +            fl = input[0];
> > +            fr = input[1];
> > +            c = input[2];
> > +            lfe = input[3];
> > +            rl = input[4];
> > +            rr = input[5];
> > +
> > +            l = clip_short(fl + (0.5 * rl) + (0.7 * c));
> > +            r = clip_short(fr + (0.5 * rr) + (0.7 * c));
> > +        } else {
> > +            /* channels must be 3-5, or >= 7. l, c, r, ? */
> > +            l = input[0];
> > +            r = input[2];
> > +        }
> 
> The ifs should hardly be inside the loop.

of course, i was just posting what i found in ffmpeg2theora.
in case someone wants to clean any of it up / apply it ...

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

it is not once nor twice but times without number that the same ideas make
their appearance in the world. -- Aristotle
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