[FFmpeg-devel] [PATCH 02/N] RV30/40 Decoder - RV30 decoder

[Michael Niedermayer]

On Sat, Dec 01, 2007 at 08:07:51PM +0200, Kostya wrote:
> Here it is. I decided to drop loop filter because
> it's not complete yet and I don't know what parameters
> should be fed to it.

[...]

> static int rv30_parse_slice_header(RV34DecContext *r, GetBitContext *gb, SliceInfo *si)
> {
>     int t, mb_bits;
>     int w = r->s.width, h = r->s.height;
>     int mb_size;
> 
>     memset(si, 0, sizeof(SliceInfo));
>     skip_bits(gb, 3);
>     si->type = get_bits(gb, 2);
>     if(si->type == 1) si->type = 0;
>     if(get_bits1(gb))
>         return -1;
>     si->quant = get_bits(gb, 5);
>     skip_bits1(gb);

>     t = get_bits(gb, 13);

t is unused


>     skip_bits(gb, r->rpr);

>     si->vlc_set = 0;

uneeded due to the memset(), either one of the 2 should be removed


[...]
> /**
>  * Decode 4x4 intra types array
>  */
> static int rv30_decode_intra_types(RV34DecContext *r, GetBitContext *gb, int *dst)
> {
>     int i, j, k;
>     int A, B;
>     int *ptr;
>     int code;
> 
>     for(i = 0; i < 4; i++, dst += r->s.b4_stride){
>         ptr = dst;

dst += r->s.b4_stride - 4 would avoid the ptr variable


>         for(j = 0; j < 4; j+= 2){
>             code = (ff_rv34_get_gamma(gb) - 1) << 1;
>             if(code >= 81*2){
>                 av_log(r->s.avctx, AV_LOG_ERROR, "Incorrect intra prediction code\n");
>                 return -1;
>             }
>             for(k = 0; k < 2; k++){

>                 A = ptr[-r->s.b4_stride] + 1;
>                 B = ptr[-1] + 1;

declaration and statement can be merged, this is also true for code


[...]
>     int code;
> 
>     code = ff_rv34_get_gamma(gb) - 1;

can be merged


[...]
> /**
>  * Initialize decoder
>  */
> static int rv30_decode_init(AVCodecContext *avctx)
> {
>     RV34DecContext *r = avctx->priv_data;
>     MpegEncContext *s = &r->s;
> 
>     r->rv30 = 1;
>     ff_rv34_decode_init(avctx);
>     if(avctx->extradata_size < 2){
>         av_log(avctx, AV_LOG_ERROR, "Extradata is too small\n");
>         return -1;
>     }
>     r->rpr = (avctx->extradata[1] & 7) >> 1;
>     r->rpr = FFMIN(r->rpr + 1, 3);
>     r->parse_slice_header = rv30_parse_slice_header;

>     r->decode_intra_types = rv30_decode_intra_types;
>     r->decode_mb_info     = rv30_decode_mb_info;

these are used just once, so a
if(rv30) A()
else     B()
would be more obvious, also it would allow gcc to inline the code


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

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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