[FFmpeg-devel] JPEG2000 decoder

[rukhsana afroz]

Hi Michael,

On Tue, Jun 21, 2011 at 7:54 PM, rukhsana afroz <rukhsana.afroz at gmail.com>wrote:

> Hi Michael,
>
>
> On Wed, Jun 15, 2011 at 10:29 PM, rukhsana afroz <rukhsana.afroz at gmail.com
> > wrote:
>
>> Hi Michael,
>>
>>
>> On Wed, Jun 8, 2011 at 5:19 PM, rukhsana afroz <rukhsana.afroz at gmail.com>wrote:
>>
>>> Hi Michael,
>>>
>>>
>>> On Sat, Jun 4, 2011 at 5:23 PM, Michael Niedermayer <michaelni at gmx.at>wrote:
>>>
>>>> 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,
>>>>
>>>
I have found the problem of the bug I am working on. I see, band coordinates
are not correctly calculated for one band. I need your help to fix this bug.

Thanks

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