[FFmpeg-devel] GSoC project (JPEG 2000)

[rukhsana afroz]

On Wed, Apr 13, 2011 at 1:46 PM, Michael Niedermayer <michaelni at gmx.at>wrote:

>
> i dont see a specific question in your mail, my suggestion is just to
> implement the missing feature.
> If you have specific questions ill try my best to help
>

Hi Michael,

The following is the patch for selective arithmetic coding bypass cblk_csty:

595c595
< static void decode_sigpass(J2kT1Context *t1, int width, int height, int
bpno, int bandno)
---
> static void decode_sigpass(J2kT1Context *t1, int width, int height, int
bpno, int bandno, int bpass_csty_symbol)
606,607c606,609
<
<                         t1->data[y][x] = (ff_mqc_decode(&t1->mqc,
t1->mqc.cx_states + ctxno) ^ xorbit) ? -mask : mask;
---
>             if (bpass_csty_symbol)
>                 t1->data[y][x] = ff_mqc_decode(&t1->mqc, t1->mqc.cx_states
+ ctxno) ? -mask : mask;
>             else
>                 t1->data[y][x] = (ff_mqc_decode(&t1->mqc,
t1->mqc.cx_states + ctxno) ^ xorbit) ? -mask : mask;
688c690
<     int passno = cblk->npasses, pass_t = 2, bpno = cblk->nonzerobits - 1,
y;
---
>     int passno = cblk->npasses, pass_t = 2, bpno = cblk->nonzerobits - 1,
y, clnpass_cnt = 0;
699a702,704
>     bpass_csty_symbols = J2K_CBLK_BYPASS & codsty->cblk_style;
>
>
702c707
<             case 0: decode_sigpass(t1, width, height, bpno+1, bandpos);
---
>             case 0: decode_sigpass(t1, width, height, bpno+1, bandpos,
bpass_csty_symbols & (clnpass_cnt > 4));
704c709,712
<             case 1: decode_refpass(t1, width, height, bpno+1);
---
>             case 1:
>             if (clnpass_cnt > 4)
>             ff_mqc_initdec(&t1->mqc, cblk->data);
>                     decode_refpass(t1, width, height, bpno+1);
706c714,717
<             case 2: decode_clnpass(s, t1, width, height, bpno+1, bandpos,
---
>             case 2:
>             if (clnpass_cnt > 4)
>             ff_mqc_initdec(&t1->mqc, cblk->data);
>             decode_clnpass(s, t1, width, height, bpno+1, bandpos,
707a719
>             clnpass_cnt = clnpass_cnt + 1;

Pages 115 -117 from the spec have illustrated this implementation. Please
let  me know if you have any suggestion.

Thanks

-- 
Rukhsana Ruby
Phd Student
Department of Electrical & Computer Engineering
The University of British Columbia
============================