theora - Sep 2009 - issue with encoding of one particular file?

Hello,

I'm using ffmpeg2theora.linux to encode video casts from http://digit.cz

For one particular episode 24, I discovered two issues:
1. minor one - at beginnig, software is reporting very big and long
result
ffmpeg2theora.linux digit24.mp4 
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'digit24.mp4':
  Duration: 00:42:41.04, start: 0.000000, bitrate: 1177 kb/s
    Stream #0.0(eng): Audio: aac, 48000 Hz, 2 channels, s16
    Stream #0.1(eng): Video: h264, yuv420p, 640x360, 25 tbr, 600 tbn,
1200 tbc
    Stream #0.2(eng): Data: rtp  / 0x20707472
    Stream #0.3(eng): Data: rtp  / 0x20707472

  0:00:00.00 audio: 0kbps video: 6819kbps, ET: 142:16:48, est. size:
2081.9 MB 

at the end, file is 110M big

2. second, major one, the resulting file can't be used, picture not
exist or is too fast / not in sync with sound

original file is played just fine

Next to this, for all video casts, both mplayer and VLC Media Player are
showing very big length of the video more then 1hour, what is not true

For encoding, I'm using
wget http://firefogg.org/nightly/ffmpeg2theora.linux
md5 a90e53aaa1081dfa206c5badd0d58e4d
ffmpeg2theora 0.24+svn16546 - Xiph.Org libtheora 1.1 20090822
(Thusnelda)
ffmpeg2theora.linux --optimize --no-upscaling --videoquality 5 --audioquality 1 

Problematic file is from
wget http://digit.superhosting.cz/digit24.mp4
md5 239724c7758a6a9a56c53f002b0f1bae

ffmpeg2theora.linux digit24.mp4
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'digit24.mp4':
  Duration: 00:42:41.04, start: 0.000000, bitrate: 1177 kb/s
    Stream #0.0(eng): Audio: aac, 48000 Hz, 2 channels, s16
    Stream #0.1(eng): Video: h264, yuv420p, 640x360, 25 tbr, 600 tbn,
1200 tbc
    Stream #0.2(eng): Data: rtp  / 0x20707472
    Stream #0.3(eng): Data: rtp  / 0x20707472

  0:42:41.04 audio: 71kbps video: 6917kbps, time elapsed: 01:52:01

How is this source video different from others? Why is the result not usable?

Thank you,
Jiri

-- 
Jiri Navratil, http://www.navratil.cz,  +420 777 224 245

On Sep 2, 2009, at 3:10 PM, Jiri Navratil <jiri at navratil.cz> wrote:
> 2. second, major one, the resulting file can't be used, picture not
> exist or is too fast / not in sync with sound
>
> original file is played just fine
I've encountered these problems as well where sometimes the audio/ 
video gradually loose sync with each other, and also where the  
framerate is doubled.

A workaround for the video being too fast seems to be manually  
specifying the input and output framerate.

I don't know of a solution to the gradual loss of sync though.

For what it's worth, these seem to be problems with ffmpeg itself and,  
being based on ffmpeg, ffmpeg2theora inherits them.

On Thu, Sep 03, 2009 at 05:27:06AM -0700, Jason Self
wrote:
> Use --inputfps to set the input framerate, and --framerate to set the  
> output. (FYI: ffmpeg2theora.linux --help will show all available  
> options.)
> 
> Bernard suggested extracting the audio/video and encoding each  
> separately to fix the sync issue. Oggz can merge them together:
http://firefogg.org/nightly/
Thx for next details. I used them to create a correct result with this
command:

ffmpeg2theora.linux --inputfps 25 --framerate 25 digit24.mp4

So far, no testing of oggz-merge. I will try to look at it later, too.

Best regards,
Jiri