[mythtv] [PATCH] Add streaming output to transcoder

Chris Petersen lists at forevermore.net
Sat Aug 16 23:37:20 EDT 2003


> In the mencoder case, it is
> necessary to buffer ~2 seconds of video (~50MB) to make it happy.  other
> programs may be less.  I could build the buffers on disk, and have a
> queued fifo, but it would really slow things down.  Unfortunately, the
> design in mythtranscode today is a circular-queue, which means there is
> no unused memory that can get swapped out, even if the queues are mostly
> empty.  That is a minor optimization I may look at in the future, but to
> me it is overengineering the problem (i.e it is only worth it if people
> are actually running out of memory with the current implemetation)

well, so far I've encoded about 34 minutes of audio (toolame mp2) and 19
minutes of video (ffmpeg | yuvscaler | mpeg2enc), and mythtranscoder is
using 28% of my gig of RAM, and growing...


> Well, unfortunately, this is a bad guess.  Most encoders were designed to
> use files as inputs.  In the case where streams were considered, it is
> normally a single stream with video and audio muxed together.

ah.  in my case, I'm using separate encoders for audio and video...

> overhead).  If mythtranscode is taking up a lot of RAM, you should see
> messages about creating new buffers, which implies something isn't
> working correctly. 

lots and lots and lots of them...  numbering over 500 now.

> I could do this, but since mencoder and ffmpeg both give status, I
> figured that would be sufficient.

yeah, but `ffmpeg | yuvscaler | mpeg2enc` produces a LOT of status - too
much to get anything useful.

fwiw, I'm using cvs from sometime earlier tonight....

-Chris



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