theora - Jun 2009 - macro block artifacts of ogv file converted from mpeg(libthusnelda I 20090527)

hi,

there is a problem when i convert some mpeg files to ogv with libthusnelda I
20090527... i don't know it this helps you but i am sending information
about it...

when i convert an mpeg file ro ogv, there are macro block artifacts on the lower
part of the video... but it doesn't happen all the time... description is
below and you can download the video files form the link below if you like...
(1MB rar file with 5 video files)
https://download.yousendit.com/UmNKckhWUnIwZ21Ga1E9PQ

video files and info:

01_original_avi_captured_with_camera.avi
320x240 PAR1:1 progressive 16.716fps mjpg avi 
this is the original footage captured by the camera

02_mpeg_converted_from_original_avi.mpg
320x240 par1:1 progressive 25fps mpeg2
this is the file i have converted to mpeg form original file with mainconcept
mpeg pro.. the video is OK

03_ogv_converted_from_original_w_firefogg_OK.ogv
320x240 PAR1:1 16,72fps ogv
this is the file i have converted to ogv from original file with firefogg
(ffmpeg2theora 0.24).. the video is OK

04_ogv_converted_from_mpeg_w_firefogg_wARTIFACTS.ogv
320x240 par1:1 25fps ogv
this is the file i have converted to ogv from mpeg file with above with firefogg
(ffmpeg2theora 0.24).. this is the problematic file... there are macro block
artifacts on the lower part of the video... this happens sometimes when i
convert from mpeg (with he same spesifications as above) to ogv. but some files
are converted ok... i don't understand it... but when i convert the same 
mpeg file with vlc which uses libtheora I 20081020 3 2 1 it is ok, there are no
artifacts (but also the 16:15 par instead of 1:1).. here is info about it..

06_vlc_converted_file_from_mpeg_NOartifactsbut rescaled.ps
320x256 16:15 par 25fps .ps? file..
this is converted form the mpeg file above by using vlc 0.99 grichenko (windows)
which uses ibtheora I 20081020 3 2 1.... the extension of the file is .ps but i
don't understand what it is... vlc converted ogg files always have this
extension on windows, which is another problem.  but it plays when i drag it
into vlc or change the extension to .ogv... THIS FILE ALSO DOESN'T HAVE ANY
MACROBLOCK ARTIFACTS...

because the same mpeg file is converted ok with vlc encoder which uses do you
think that this problem is because of ffmpeg2theora or libthusnelda I 20090527
?libtheora I 20081020 is ok...


 .-_-.



      
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://lists.xiph.org/pipermail/theora/attachments/20090605/8c24964b/attachment.htm

On Fri, Jun 5, 2009 at 5:07 PM, Orton AKINCI aka .-_-.
<ortonak at yahoo.com> wrote:
> hi,
>
> there is a problem when i convert some mpeg files to ogv with libthusnelda
I
> 20090527... i don't know it this helps you but i am sending information
> about it...
This appears to be an ffmpeg problem.

If I use ffplay from ffmpeg SVN-r18213 to play
02_mpeg_converted_from_original_avi.mpg I see the flashing block in
the lower left corner.

Transcoding the file using ffmpeg2theora-0.24-thusnelda.linux32.bin
gives the same result in the transcoded output, which is unsurprising
because it uses a recent FFMPEG for decoding.

I will report this to the ffmpeg developers.

The reason you don't see it with other older converters must be
because they are using a different version of ffmpeg for decode.

Thank you for the detailed report which allowed me to quickly exclude
many possible causes.

In the future you may want to use zip or tar for sending files like
this, because unrar is not free software many Linux distributions do
not ship it and developers on these platforms may need to undertake
extra effort to decode your archive.