[FFmpeg-devel] JPEG2000 decoder

rukhsana afroz rukhsana.afroz at gmail.com
Thu May 5 23:18:02 CEST 2011

On Mon, May 2, 2011 at 3:13 PM, Michael Niedermayer <michaelni at gmx.at>wrote:

> for p1_01.j2k i get
> unsupported marker 0xA17D at pos 0x145
> unsupported marker 0xEFC8 at pos 0xbfa
> Missing EOC
> before any other output, and i would not trust data after errors
> the first error happens after a 0xFF93
> so i would suspect theres some difference in init_tile() or
> decode_packets() or a function called by them or something surrounding
> that code
> I suggest you first check if the s->buf points to the same data
> after these in our decoder and jasper and i suspect it wont.
> From there its finding out where and why it starts to differ
> Hi Michael,

s->buf points to the decoded raw codestream extracted from the file.
Therefore, it does not differ between our decoder and jasper. The bug, I
think is in the extracted parameters from this codestream. Extracted
parameters define the codeblock and the data in the codeblock. I think, the
bug is either is in "ff_j2k_init_component" called from init_tile or in
"decode_packet" function. Actually all parameters are extracted in the
function "ff_j2k_init_component". Therefore, I think i need to see whether
the extracted parameters are right comparing with jasper. If you check the
j2kdec code, you will find there is a function:

void dump(J2kDecoderContext *s, FILE *fd)

It prints all extracted parameters. I am writing similar function in jasper
in order to compare.

Please let me know if you have any suggestion.


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

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