[FFmpeg-soc] [RFC] Possible jpeg2k decoder rewrite

[Jai Menon]

On Wed, Jun 10, 2009 at 11:45 AM, Michael Niedermayer<michaelni at gmx.at> wrote:
> On Tue, Jun 09, 2009 at 03:25:52PM +0000, Jai Menon wrote:
>> On Sat, May 2, 2009 at 8:23 PM, Michael Niedermayer<michaelni at gmx.at> wrote:
>> > On Sun, May 03, 2009 at 12:56:02AM +0530, Jai Menon wrote:
>> >> On 4/26/09, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> > On Sun, Apr 26, 2009 at 05:47:11PM +0530, Jai Menon wrote:
>> >> >  > On 4/26/09, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> >  > > On Sun, Apr 26, 2009 at 04:17:48PM +0530, Jai Menon wrote:

[...]

>> I think I have narrowed the problem down to the tagtree decoding code,
>> but don't know what to fix and where to fix.
>
> in the most generic sense you should have some difference between some
> reference implementation and our decoder
> whereever that is there is prior code that can be tested for being
> different or not.
>
> if you tell us what variable with what value in what line of our code differs
> from what in what line of some reference we might be able to help ...

I tried rewriting that part from scratch based on the spec, and still
get the same problems. So maybe my assumption was wrong.

The file i'm using is file
http://samples.mplayerhq.hu/jpeg2000/j2kp4files_v1_2.zip/testfiles_jp2/file3.jp2

Here is jasper's output for that file:

packet size is 278
packet size is 58
packet size is 61
packet size is 785
packet size is 162
packet size is 160
packet size is 2883
packet size is 567
packet size is 533
packet size is 10259
packet size is 2056
packet size is 1905
packet size is 36007
packet size is 7836
packet size is 7421
packet size is 111139
packet size is 30613
packet size is 29299
no.  of packets 18

And here is what our decoder says :

size of packet is 278
size of packet is 58
size of packet is 61
size of packet is 785
size of packet is 162
size of packet is 160
size of packet is 2883
size of packet is 567
size of packet is 533
size of packet is 10259
size of packet is 1
^^^^^^^^^^^^^^^^^^^^^    <------- Packets arent read correctly from here on
size of packet is 21
size of packet is 1
size of packet is 31
size of packet is 1
size of packet is 164
size of packet is 35
size of packet is 42
no.  of packets 18

I'll continue looking into this.


-- 
Regards,

Jai