From: Ronan Cunniffe (ronan at domain cunniffe.net)
Date: Tue 30 Jul 2002 - 20:00:50 IST
I've been doing some video compression from VHS using mjpegtools, and trying
different bitrate/quantisation/algorithm mixes to see what gives best results.
The whole thing is a three stage pipeline:
lav2yuv capture.avi | yuvdenoise | mpeg2enc --lots-of-args -o capture.m1v
(100 mins) (260 mins) (236 mins)
The times are cpu time for a particular segment of video. All compression runs
use the same first two stages - 360 mins. Obviously, I want to do that once and
send the results to lots of encoding processes.
I did the following:
$ mkfifo f1
$ lav2yuv capture.avi | yuvdenoise | tee f1 | mpeg2enc (blah blah) &
$ cat f1 | mpeg2enc (different blah blah)
And hey! It works! Until somebody dies! Yippe... oh.
I could wrap mpeg2enc in a script that detected a death-by-error and catted the
fifo to /dev/null, but has anyone got a better way of doing this?
Oh, and writing the result of the first to stages to disk is not a better way.
Unless you have a very, very, very big disk. :-)
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