[theora] Theora for webcam/conferencing use
Basil Mohamed Gohar
abu_hurayrah at hidayahonline.org
Thu Oct 15 09:11:47 PDT 2009
Yesterday and today I decided to try out broadcasting a video stream
using Theora from my computer's built-in webcam. I was pleasantly
surprised to find that, while maintaining a rate of less than 150kbps,
the stream was of quite a suitable quality sending 640x480 video at 15
frames per second. For now, this is video only, by the way, I did not
include any audio in the stream yet.
Yesterday, I used `--video-quality 5`, while today I'm using
`--video-rate-target 150 --soft-target`. Using constant quality
resulted in more even video despite motion, while using a constant rate
yielded better video where there was no motion and worse when there was
- both to be expected.
In both cases, my family were quite pleased with the results, and
although there is obviously a delay (I'm coupling this with an IceCast2
streaming server), for one-way communications, such as broadcasts or
webcasts, it's quite suitable and can scale quite well for the purpose
it is serving.
My purpose in mentioning all of this is to ask others' experience in
using Theora for low-bandwidth or video conferencing settings. Are
there more advanced settings that are better optimized for a
"talking-head" kind of video, where there's more motion in a fixed area
of a frame than on the fringes? Also, maybe something that can handle
the inevitable white-balance and brightness adjustments that come with
today's automatically adjusting cameras...
Just some ideas. I was also thinking of coupling --soft-target along
with --video-quality to get a minimum video quality, which might be the
key to what I am asking.
Anyone else have some thoughts on this?
For those that are interested, here are my command-line:
> time ffmpeg -f video4linux2 -s 640x480 -r 15 -i /dev/video0 -pix_fmt
> yuv420p -f yuv4mpegpipe - 2>/dev/null |
> ~/packages/theora/examples/encoder_example --video-rate-target 150
> --soft-target - | tee /home/basil.gohar/Videos/webcam-capture-`date
> +%Y%m%d`.ogv | oggfwd -d 'Live webcam view of me at work' -g 'Webcam'
> -n 'Basil at work' aalimraan.hidayahonline.net 8000
> ***passwordremoved*** /basil-at-work.ogv
Feel free to tune in to my webcam, too. The URL for it it:
Works great in Firefox 3.5 & VLC. ;)
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