[FFmpeg-devel] [PATCH 03/N] RV30/40 Decoder - RV40 decoder

[Michael Niedermayer]

On Sat, Dec 01, 2007 at 08:08:59PM +0200, Kostya wrote:
> The same as RV30 counterpart - without loop filter.

[...]

>     for(i = 0; i < AIC_MODE1_NUM; i++){
>         // For some reason every tenth VLC table is empty
>         // So skip it for consistency
>         // XXX: redo without this hack
>         if((i % 10) == 9) continue;
>         init_vlc(&aic_mode1_vlc[i], AIC_MODE1_BITS, AIC_MODE1_SIZE,
>                  aic_mode1_vlc_bits[i],  1, 1,
>                  aic_mode1_vlc_codes[i], 1, 1, INIT_VLC_USE_STATIC);

i assume this %10 hack can be avoided by chaning the tables and using
B + C*9 instead of B + C*10, if so it should be done before this reaches
svn as otherwise it likely will never be cleaned up ...


[...]
> static int get_dimension(GetBitContext *gb, const int *dim1, const int *dim2)
> {

>     int val, t;
> 
>     t = get_bits(gb, 3);
>     val = dim1[t];

int t   = get_bits(gb, 3);
int val = dim1[t];


>     if(!val && dim2)
>         val = dim2[(t*2 | get_bits1(gb)) & 3];

if(val<0)
    val= dim[get_bits1(gb) - val];

and with matching change to dim (and removial of dim2)


[...]
>     if(!si->type || !get_bits1(gb))
>         rv40_parse_picture_size(gb, &w, &h);
>     si->width  = w;
>     si->height = h;

checking w/h for being valid before using them would be a good idea


[...]
>                         if(B == -1 || B == 0 || B == 1)

if(B<2)


[...]
>     int blocks[RV34_MB_TYPES];
>     int count = 0;
> 
>     if(!r->s.mb_skip_run)
>         r->s.mb_skip_run = ff_rv34_get_gamma(gb);
> 
>     if(--r->s.mb_skip_run)
>          return RV34_MB_SKIP;
> 
>     memset(blocks, 0, sizeof(blocks));

int blocks[RV34_MB_TYPES]={0};


>     if(r->avail[0])
>         blocks[r->mb_type[mb_pos - 1]]++;
>     if(r->avail[1])
>         blocks[r->mb_type[mb_pos - s->mb_stride]]++;
>     if(r->avail[1] && r->avail[2])
>         blocks[r->mb_type[mb_pos - s->mb_stride + 1]]++;
>     if(r->avail[1] && r->avail[3])
>         blocks[r->mb_type[mb_pos - s->mb_stride - 1]]++;

if(r->avail[1]) can be factored out


[...]
>     if(s->pict_type == P_TYPE){
>         if(prev_type == RV34_MB_SKIP) prev_type = RV34_MB_P_16x16;
>         prev_type = block_num_to_ptype_vlc_num[prev_type];

block_num_to_ptype_vlc_num can be changed to avoid the if()


[...]
> /**
>  * Initialize decoder
>  */
> static int rv40_decode_init(AVCodecContext *avctx)
> {
>     RV34DecContext *r = avctx->priv_data;
>     static int tables_done = 0;
> 
>     r->rv30 = 0;
>     ff_rv34_decode_init(avctx);
>     if(!tables_done){
>         rv40_init_tables();
>         tables_done = 1;
>     }

you could check an entry of one of the tables which would avoid the
tables_done var

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

No human being will ever know the Truth, for even if they happen to say it
by chance, they would not even known they had done so. -- Xenophanes
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