[mythtv-users] How small can I get my captures?

Ray Olszewski ray at comarre.com
Sat Jun 14 09:56:51 EDT 2003


At 09:58 AM 6/14/2003 -0500, John P DeVale wrote:
>>[...]
>>Have you tried using the MPEG4 option?  For me, with the default
>>settings, this produces files approximately 400mb for 30 minutes / 900mb
>>for an hour.
>ARRGH!  This is *most* annoying.  For me the default MPEG4 settings 
>produce files that are 3-4 GB per hour.  Does anyone know why this might 
>be and how to fix it?

Are you sure of this? That is, are you sure the relevant recording profile 
is set for MPEG4 and not RTJPEG? Here, I'm using the default bitrate 
settings, but 320x240 captures, and I'm seeing about 250-300 MB/hour for 
timed recordings (I don't at the moment have a "live" TV buffer to check). 
This makes 900 MB/hr about right for the standard 480x480 Myth settings. 
Your numbers are more consistent with usual values for RTJPEG than MPEG4.

If you are sure ... the usual reason for increased size of MPEG4 captures 
(in general; this is not specific to Myth) is a noisy TV signal. I just 
cleaned up my signal here, and my vcr/avifile captures dropped in size by 
about a third, with no settings changes.

Here, the default bitrate is 2200 Kbps, or about 300 KBps, which works out 
to  1.1 GB/hr, consistent with John's experience but not yours. "Scale 
bitrate for frame size" is selected, with quality range 2 maximum, 15 
minimum. Audio is MP3, quality 7. You might want to double check that you 
and he (and I) really are using the same "default" values.

BTW, my results are for the Debian prepacks of Myth 0.8.





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