theora dev - May 2006 - Theora and Vorbis problems

Hi all,

 I've been trying to add Vorbis to my Theora stream, and it seems to be
working in mplayer and oggz-validate seems fine with it (apart from the
missing EOS flags in the final pages, but this is expected). Xine and
Cortado are both making a mess of it though:

http://www.firestorm.cx/files/followthedot.ogg

It's a very boring moving green dot - it moves smoothly in mplayer,
bounces around in Xine and Cortado. The audio is static, please don't
play this with the volume up high!

Any ideas?

-Phil <phil@firestorm.cx>

(ps. Would theora@ be a better list for this kind of question?)

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On Wed, May 24, 2006 at 06:29:06PM +0100, Philip Heron wrote:
> http://www.firestorm.cx/files/followthedot.ogg
FWIW, it works fine in Quicktime Player. VLC seemed to have a little 
trouble getting going, but once it openned the video window it was ok.

Assuming I'm seeing the right thing. There's a chroma green field with
a lighter green, one pixel dot moving from left to right across the top
of the frame. This repeats, with static for audio with occasional drops.
The frame goes white a bit before the audio quits?

 -r
> (ps. Would theora@ be a better list for this kind of question?)
Either list is probably fine. Assuming you're creating this by using 
libtheora directly from your program this is the more appropriate list.

Hi,

While it's true your file seems valid spec-wise, it suffers from being 
poorly multiplexed... ie coarse muxing.

This is the first video page
--------------------------------------
Page Location : 73374 to 77589
Ver No      : 0
Head Flags  :
Granule Pos : 254
Serial No   : 1792863441
Seq No      : 2
Checksum    : 279992667
Num Segs    : 255
------------------------
Head Size   : 282
Data Size   : 3933
Page Size   : 4215
Num Packets : 255
--------------------------------------

There's about 20 pages of audio before the first video page, and the first 
video page contains 255 frames. This is due to the way ogg sorts pages by 
end-time, it causes pathological files to be created with the default paging 
algorithm particularly when the size of the video packets is small. VLC will 
probably play, but most others things probably won't. My directshow code has
will only let there be about a 75 packet delta between current play time 
between streams. That's typically about 3 seconds, which is already pretty 
excessive. Everything could just make their buffers even bigger... but my 
position is that these files are broken and it's better to discourage people
from making them, rather than making stupidly large buffers. Also files like 
this will cause problems as more embedded devices start to use theora.

 Basically the file is "ten seconds of audio data" then "ten
seconds of
video data" rather than being nicely interleaved. When you mux,
particularly
when you mux "easy" video such as this one, you have to make sure you
flush
the stream after some number of packets ~50 say, or some amount of time say 
1-2 seconds if more than that would normally continue to fit in one page. I 
think ffmpeg2theora is the only tool currently that properly does this.

Cheers,

Zen.
----- Original Message ----- 
From: "Philip Heron" <phil@firestorm.cx>
To: "Theora Development" <theora-dev@xiph.org>
Sent: Thursday, May 25, 2006 1:29 AM
Subject: [Theora-dev] Theora and Vorbis problems

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