fast video encoding

gregorth gregor.thalhammer at gmail.com
Wed Jul 29 10:14:31 CEST 2009


Hi all,

for a scientific application I need to save a video stream to disc for
further post processing. My cam can deliver 8bit grayscale images with
resolution 640x480 with a framerate up to 100Hz, this is a data rate
of 30MB/s. Writing the data uncompressed to disc hits the data
transfer limits of my current system and creates huge files. Therefore
I would like to use video compression, preferably fast and high
quality to lossless encoding. Final file size is not that important.
Because of the hardware I am bound to WinXP.

I already tried pymedia for encoding to mpeg2, however I only managed
to get a framerate of about 30-40fps (on a 1.8GHz dual core). There is
still room for improvements in my code, but before trying hard I want
to ask for advices or other possibilities. I also found gstreamer with
pygst python bindings, which seems to be more modern (and performant?)
package than pymedia. I did not yet try it, especially since I didn't
find a simple code example of how to use it for my use case. Can
somebody give me a hint?

I also found huffyuv or lagarith which is provided as a directshow
codec for Windows. Can somebody give me a hint how to use a directshow
codec with python?

I am a novice with video encoding. I found that few codecs support
gray scale images. Any hints to take advantage of the fact that I only
have gray scale images?

Thanks for any help

Gregor




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