[FFmpeg-soc] [PATCH] jpeg2k : support higher sample precision

[Michael Niedermayer]

On Sun, Jun 21, 2009 at 04:35:20PM +0000, Jai Menon wrote:
> Hi,
> 
> Attached patch fixes decoding of files where component precision > 8.
> 
> Possible test files are :
> 
> codestreams_profile1/p1_04.j2k
> testfiles_jp2/file6.jp2
> testfiles_jp2/file7.jp2
> 
> Posting here for comments.
> 
> -- 
> Regards,
> 
> Jai

>  j2kdec.c |   35 ++++++++++++++++++++++++++++++++---
>  1 file changed, 32 insertions(+), 3 deletions(-)
> 10381c8c4a6486b49b3013bc0683cb6d62f9161e  high_precision.patch
> Index: j2kdec.c
> ===================================================================
> --- j2kdec.c	(revision 4434)
> +++ j2kdec.c	(working copy)
> @@ -54,7 +54,7 @@
>      uint8_t cbps[4]; ///< bits per sample in particular components
>      uint8_t sgnd[4]; ///< if a component is signed
>      uint8_t properties[4];
> -
> +    int precision;
>      int ncomponents;
>      int tile_width, tile_height; ///< tile size
>      int numXtiles, numYtiles;

> @@ -225,6 +225,8 @@
>      for (i = 0; i < s->ncomponents; i++){ // Ssiz_i XRsiz_i, YRsiz_i
>          uint8_t x = bytestream_get_byte(&s->buf);
>          s->cbps[i] = (x & 0x7f) + 1;
> +        if (s->cbps[i] > s->precision)
> +            s->precision = s->cbps[i];
>          s->sgnd[i] = (x & 0x80) == 1;
>          if (bytestream_get_byte(&s->buf) != 1)
>              return -1;

FFMAX

[...]
> @@ -806,6 +815,26 @@
>  
>          line += s->picture.linesize[0];
>      }
> +    } else {
> +        for (; y < tile->comp[0].coord[1][1] - s->image_offset_y; y++) {
> +            uint16_t *dst;
> +            x = tile->comp[0].coord[0][0] - s->image_offset_x;
> +            dst = line + x * s->ncomponents * 2;
> +            for (; x < tile->comp[0].coord[0][1] - s->image_offset_x; x++) {
> +                for (compno = 0; compno < s->ncomponents; compno++) {

> +                    *src[compno] = av_rescale(*src[compno], (1 << 16) - 1,
> +                                              (1 << s->cbps[compno]) - 1);

av_rescale is too slow


> +                    *src[compno] += 1 << 15;
> +                    if (*src[compno] < 0)
> +                        *src[compno] = 0;
> +                    else if (*src[compno] >= (1 << 16))
> +                        *src[compno] = (1 << 16) - 1;
> +                    *dst++ = *src[compno]++;

av_clip()


> +                }
> +            }
> +            line += s->picture.linesize[0];
> +        }
> +    }
>      return 0;
>  }
>  

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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
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