[FFmpeg-soc] [soc]: r334 - jpeg2000/j2kenc.c

[Michael Niedermayer]

Hi

On Sat, Jul 07, 2007 at 01:54:31AM +0200, k.nowosad wrote:
> Author: k.nowosad
> Date: Sat Jul  7 01:54:31 2007
> New Revision: 334
> 
> Log:
> adds lossy compression with possibility to limit the number of bytes contributed by a single tile by setting maxtilelen field in the encoder context [i'll connect it with api in the nearest future];

[...]
> +static int lut_nmsedec_ref[1<<NMSEDEC_BITS],
> +    lut_nmsedec_ref0[1<<NMSEDEC_BITS],
> +    lut_nmsedec_sig[1<<NMSEDEC_BITS],
> +    lut_nmsedec_sig0[1<<NMSEDEC_BITS];
> +

these can be vertically aligned


[...]
> +        tile->mindr = 1e10;

FLOAT_MAX


[...]
>  
> +void init_luts()

non static with no prefix


[...]
> +static double getwmsedec(int nmsedec, int bandpos, int lev, int bpno)
> +{
> +   static const double dwt_norms[4][10] = {
> +    {1.000, 1.500, 2.750, 5.375, 10.68, 21.34, 42.67, 85.33, 170.7, 341.3},
> +    {1.038, 1.592, 2.919, 5.703, 11.33, 22.64, 45.25, 90.48, 180.9},
> +    {1.038, 1.592, 2.919, 5.703, 11.33, 22.64, 45.25, 90.48, 180.9},
> +    {.7186, .9218, 1.586, 3.043, 6.019, 12.01, 24.00, 47.97, 95.93}};
> +
> +    double t = dwt_norms[bandpos][lev] * (1 << bpno);
> +    return t * t * nmsedec / 8192.0;
> +}

as all numbers are integers or fixed point, plesse use int(64_t) instead of
double


[...]
>                          ff_aec_encode(&t1->aec, ctxno, (t1->data[k][j] < 0 ? 1:0) ^ xorbit);

the ? 1:0 is superflous


[...]
> +            if (dr < tile->mindr)
> +                tile->mindr = dr;
> +            if (dr > tile->maxdr)
> +                tile->maxdr = dr;

tile->mindr= FFMIN(tile->mindr, dr);


[..]
>  /* tier-2 routines: */
> @@ -946,7 +1041,7 @@ static void encode_packet(J2kEncoderCont
>  
>          for (pos=0, yi = band->prec[precno].yi0; yi < band->prec[precno].yi1; yi++){
>              for (xi = band->prec[precno].xi0; xi < band->prec[precno].xi1; xi++, pos++){

> -                cblkincl[pos].val = band->cblk[yi * cblknw + xi].npassess == 0 ? 1:0;
> +                cblkincl[pos].val = band->cblk[yi * cblknw + xi].ninclpassess == 0 ? 1:0;

superfous ?1:0


[...]
> +static int getcut(J2kCblk *cblk, double threshold)
> +{
> +    int passno, res = 0;
> +    for (passno = 0; passno < cblk->npassess; passno++){
> +        int dr;
> +        double dd;
> +
> +        dr = cblk->passess[passno].rate
> +           - (res ? cblk->passess[res-1].rate:0);
> +        dd = cblk->passess[passno].disto
> +           - (res ? cblk->passess[res-1].disto:0.0);
> +
> +        if (dd >= dr * threshold)
> +            res = passno+1;
> +    }
> +    return res;
> +}

double best= FLOAT_MAX;
for (passno = 0; passno < cblk->npassess; passno++){
    double rd= cblk->passess[passno].disto + cblk->passess[passno].rate*threshold;
    if(rd < best){
        res= passno+1;
        best= rd;
    }
}


[...]
> +static void rate_control(J2kEncoderContext *s, J2kTile *tile, int tileno)
> +{
> +    int i, ok;
> +    uint8_t *oldbuf = s->buf;
> +    double lo = tile->mindr, hi = tile->maxdr, resthres = lo;
> +    for (i = 0; (i < 32); i++){
> +        double thres = (lo+hi)/2;
> +
> +        ok = 0;
> +        s->buf = oldbuf;
> +        truncpassess(s, tile, thres);
> +        encode_packets(s, tile, tileno);
> +
> +        if (s->buf - oldbuf > s->maxtilelen)
> +            lo = thres;
> +        else{
> +            resthres = hi = thres;
> +            ok=1;
> +        }
> +    }
> +    if (!ok){
> +        s->buf = oldbuf;
> +        truncpassess(s, tile, resthres);
> +        encode_packets(s, tile, tileno);
> +    }
> +}

this seems to do strict CBR, i think using AVFrame.quality factor as
lambda/threshold would make more sense most of the time, that said iam
not against an optional CBR mode which uses max/min_rate


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

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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