[mythtv-users] bitrate questions

Chris Petersen lists at forevermore.net
Mon Aug 16 18:34:33 EDT 2004


> But on the other hand, SVCDs are 480x480 res, always mpeg2, look
> about the same (or even just slightly better) as my mythtv recordings
> but they manage to squeeze 80-100 minutes on a 800 MB CD.

Actually, svcd looks like crap if you put more than 60 minutes onto an 
800M disk.  SVCD video bitrates at 1500kbps (with audio at 160), which 
is about 65 minutes per 795 megs (to leave 5M of space for svcd file 
system stuff), are about as low as you can go and still maintain a 
decent amount of quality.

However, this really doesn't answer the quality difference issue.  I 
have plenty of 720x480 avi files (presumably mpeg4/xvid/divx) that are 
fractions of the size of my 640x480 nuv files (say, 350M for 40 minutes 
of commercial-free show, compared to 2-3G for mine) with WAY better 
quality, no noticeable artifacts, etc.

Granted, my nuv files (recorded around 2800kbps) have high-quality mp3 
audio, but it shouldn't account for the gigabytes of difference in file 
size.  My nuv files also look pretty decent, but I've set the "max" 
mpeg4 quality to 1, and the "min" to 2.  (bumping up the "min" setting 
was by far the best thing I did to improve the image quality)

Perhaps it relates to 3:2 pulldown?  Is this too processor-intensive for 
myth to do realtime?  I'd happily take a disk-hit to start (say, 10-20G 
per hour) to have it later compress down with 3:2 pulldown, deinterlace, 
etc., to something around 500M/hour without commercials.

-Chris


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