[mythtv-users] Tutorial on Encoding (mostly re: file sizes)

Robert Tsai rtsai1111 at comcast.net
Tue Sep 20 19:45:01 UTC 2005


On Tue, Sep 20, 2005 at 02:31:36PM -0500, Tony McDowell wrote:
> >I doubt that you can see the difference between a 720x480 pixel and
> >a 480x480 pixel recording, so I would recommed go down to 480x480
> >pixels. That saves 25% of the data. If you want to export to DVD
> >you might however consider 720x480 pixels and keep the recordings
> >in MPEG2. Also if you want to use the output of a PVR-350 you
> >should keep the recordings in MPEG2. In all other cases you can let
> >MythTV transcode to MPEG4.
> >
> >The encoding rate is very much up your personal taste. If your
> >signal is bad you need a higher data rate. I usually record 480x576
> >pixels (PAL) at 4.5 Mbits/s in MPEG2 and transcode it to 1.4
> >Mbits/s in MPEG4. On some channels I can see the artifacts, on
> >others I can't (except in special situations like fast scrolling
> >text). Shows that I want on DVD are recorded at 720x576 pixels at
> >4.5 Mbits/s in MPEG2.
> 
> Thanks for the insight.  If I just keep it as MPEG2, what kind of
> file size should I expect?  I'm imagining about a gigabyte per hour.
> Is that high, low, other? 

FWIW, 1GB/hr is Tivo's "Basic Quality" setting. Their "Best Quality"
setting is about 3GB/hr.

--Rob
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