[FFmpeg-devel] JPEG2000 decoder

[Michael Niedermayer]

On Sat, Jun 04, 2011 at 06:06:51AM -0700, rukhsana afroz wrote:
> Hi Michael,
> 
> On Sat, Jun 4, 2011 at 5:26 AM, rukhsana afroz <rukhsana.afroz at gmail.com>wrote:
> 
> > Hi Michael,
> >
> >
> > On Fri, Jun 3, 2011 at 10:36 AM, Michael Niedermayer <michaelni at gmx.at>wrote:
> >
> >> On Fri, Jun 03, 2011 at 02:25:26AM -0700, rukhsana afroz wrote:
> >> > Hi Michael,
> >> >
> >> > On Wed, Jun 1, 2011 at 3:42 AM, rukhsana afroz <
> >> rukhsana.afroz at gmail.com>wrote:
> >> >
> >> > > Hi Michael,
> >> > >
> >> > >> maybe jaspers and ours advance the pointer at a slightly different
> >> > >> spot in the implementation
> >> > >>
> >> > >>
> >> > > As per the discussion on IRC chat, I checked where s->bit_index gets
> >> > > modified. I see, in our decoder that s->bit_index has been manually
> >> set to 8
> >> > > at the beginning of decoding packet. whereas, in jasper, I did not see
> >> this.
> >> > > Also, jasper always reads the entire byte to check present bit even
> >> for
> >> > > other files, like file1.jp2 etc. Whereas, our decoder does not do so.
> >> I need
> >> > > your suggestion on this as i do not find any clue in the doc for this.
> >> I am
> >> > > waiting for you on the IRC chat.
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > I have rebased the codebase against ffmpeg and also decode_packet
> >> function
> >> > works properly comparing with jasper. However, it gets segmentation
> >> fault
> >> > somewhere in decode_cblk function for adding new code. Tomorrow I will
> >> be in
> >> > chat to discuss this code. My new code rebased with ffmpeg is in:
> >> >
> >> > https://github.com/rukhsana/ffmpeg_j2k
> >>
> >> thanks
> >>
> >> btw
> >>
> >> floor_log2() can be replaced by av_log2()
> >>
> >>
> > I have pushed another branch r2 now. Could you please help check whether
> > the initialization of contexts (which has been done for every codeblock
> > segment) is ok compared with jasper? I think, there some problem in this. I
> > am checking as well. There are some problems in decode_cblk function, i need
> > to debug thoroughly.
> 
> 
> 
> ff_mqc_initdec function have both context and data initialization. I think,
> context and data initialization should be separated.

yes

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

In fact, the RIAA has been known to suggest that students drop out
of college or go to community college in order to be able to afford
settlements. -- The RIAA
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