[theora] Encoding from fifo's

Cameron Kerr cameron.kerr at paradise.net.nz
Sun Feb 2 17:57:04 PST 2003

Hello, I'm new to the list, so if this is an FAQ, please point me to the
relevant docs.

I'm playing with Theora, to see what kind of quality I can expect (I
realise its not for production use yet). I've download the source from 
CVS, and got it to build, with the example encoder and player.

While trying to find something to serve as a good source of input, I
decided I'd use a DVD, since the input would be of a good quality. Since
dumping the stream to a yuv4mpeg file is prohibitively expensive on my
system (no where near enough room), I decided I'd try encoding from two

I set up mplayer to give me the output

cd /tmp
mkfifo stream.yuv
mkfifo audiodump.wav
mplayer -dvd 2 -vo yuv4mpeg -ao pcm

That part works fine.

I then set up encoder_example as follows

cd /tmp
encoder_example -a 3 -v 7 stream.yuv audiodump.wav

It correctly identifies the input streams (and therefore can read
correctly), however, when it gets to its compression loop, it blocks.

I tried setting up mplayer as the reader also

mplayer -audiofile /tmp/audiodump.wav /tmp/stream.yuv

It start correctly, and brings up the viewing window, but doesn't start
to play (I'm just left with a black screen)

Finally, I try using cat, just to make sure the source mplayer isn't at

cat /tmp/audiodump.wav > foo &
cat /tmp/stream.yuv > bar &

And the files grow and grow, so that works ok.

I think perhaps encoder_example is trying to seek in the stream perhaps.
Has anyone done this before?


Cameron Kerr
Email:   cameron.kerr at paradise.net.nz
Website: http://nzgeeks.org/cameron/

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