[theora-dev] Suggestions and questions

Philip Jägenstedt philipj at telia.com
Wed Oct 2 11:48:59 PDT 2002


I'm not a developer but it takes one to answer my questions. I was just 
thinking about how the command line encoder could work in the end (after 
having played with encoder_example)
Some ideas:
1. There could be the option of having a -q switch (just like oggenc) 
controlling BOTH audio and video so that for each level of q the sum of 
video and audio bitrates could be known (sort of like the nominal in 
Vorbis). In this case there should also be some switch controlling how 
much to prioritize audio and video respectively (for example: 0=top 
audio priority, 1=equal, 2=top video priority). The point would be the 
ease of predicting file size and perhaps more important the ease of 
matching corresponding video and audio qualities.

2. Instead of this buisness of predicting file size, could there be an 
option where you first deside file size? Is it possible to scan the 
video and audio and to somehow register an "ease of compression" value 
for bunches of audio samples and video frames? If yes, then these values 
could then be used to determine exactly how many bits allowed for audio 
and video while matching file size and still not using the same bitrate 
for the entire file. (a 0-1-2 audio-video control like in previous 
question should apply to this too).

3. Would it be possible to work into the theora framework the 
possibility that a portion of a video file could be played from an 
external file? Example: I want my Star Trek TNG episodes from DVD to 
drive. The opening and titles are the same in each episode (almost) and 
therefore I want to save space by forking them in like I said. Is this 
possibly not the job of theora but rather some higher level mechanism, 
or am I just being stupid? Perhaps something like those strange text 
files that hide in front of wmv streams are what should do this, sort of 
a playlist only one clip is forked into another. If the ogg had 2 
logical streams there wouldn't be a problem putting something in 
between, would there?

4. Could there a standard "aspect ratio" (like DVDs and mpegs have) tag 
in the ogg file that would allow for any future players to prescale the 
video (otherwise, you must resize video prior to encoding, hence losing 
data or creating more data).

Bye! (sorry if I'm off-topic, non-developer here)

<p>--- >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-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.

More information about the Theora-dev mailing list