As I understand it the current plan is to make it possible to losslessly transcode VP3 video to Theora video. In my experience, one of the "features" of VP3 is it drops frames in the event that there is little/no movement in a frame, or if "drop frames" is enabled, to drop frames if the data rate is getting too high. I understand that the way that VP3 does this in QuickTime is it changes the duration of the previous frame. The Ogg format does not allow for variable frame durations. What are the plans to reconcile this disparity? Colin. --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'theora-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.
good question. We had some sort of 'null frame' flag in Windows I think,
but I can't recall exactly how it worked... it might have been at the AVI
layer.
Of course one can always encode a frame with all uncoded blocks, but that's
a bit expensive. There should be a way to mark a frame as completely uncoded.
Anyway, if this is to be possible at all, we need to get a handle on the
upside-down problem as well.
-----Original Message-----
From: Colin Mckellar [mailto:c.mckellar@student.murdoch.edu.au]
Sent: Wed 7/23/2003 10:57 AM
To: theora@xiph.org
Cc:
Subject: [theora] Question about converting VP3 to Ogg Theora
As I understand it the current plan is to make it possible to
losslessly transcode VP3 video to Theora video.
In my experience, one of the "features" of VP3 is it drops
frames in
the event that there is little/no movement in a frame, or if "drop
frames" is enabled, to drop frames if the data rate is getting too
high. I understand that the way that VP3 does this in QuickTime is it
changes the duration of the previous frame. The Ogg format does not
allow for variable frame durations. What are the plans to reconcile
this disparity?
Colin.
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I guess I thought someone was going to check whether there was really a problem.
Assuming there's a consensus we need this, I'll add it to the spec, but
someone needs to munge the C code.
-----Original Message-----
From: Maik Merten [mailto:maikmerten@gmx.net]
Sent: Wed 7/23/2003 1:50 PM
To: theora@xiph.org
Cc:
Subject: Re: [theora] Question about converting VP3 to Ogg Theora
Dan Miller wrote:
> Anyway, if this is to be possible at all, we need to get a handle on the
upside-down problem as well.
http://www.xiph.org/archives/theora-dev/200307/0004.html
Hmmmm... I didn´t notice someone vetoing the VP3-compatiblity flag on
theora-dev...
Or did I miss something?
Maik
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