[mythtv-users] RE: MPEG-2 to MPEG-4 Transcoding comparisons

[Joseph A. Caputo]

On Tuesday 18 November 2003 17:41, Augustin Chan wrote:
> Bringing up an old thread -
>
> Anyway, the default bitrate for transcoding to MPEG4 is 1500, not
> 2200, which would explain the difference in file size between what he
> remembers and what he currently sees.
>
> Half hour shows for me now size out to around 380MB, 1 hour shows
> about 770MB.
>
> A general question for those who are DivX/Encoding savvy:
>
> I notice when viewing a DVD-ripped avi file, that they use very very
> small bitrates (on the order of 700 to 800).  And yet the quality is
> excellent.  I was unable to replicate this quality when initially
> doing the encode at 6000 MPEG2 and transcoding to MPEG4/800 kbps.  Is
> this a function of the software doing the transcode?  Is this what
> the 'use high quality encoding' checkbox will do for me?


My guess is whatever you're using to transcode your DVD rips is using a 
2-pass encoding scheme (as well as possibly VBR).  2-pass generally 
yields a higher quality for the same bitrate.  I believe mythtranscode 
only does 1-pass (though I don't know for sure).

-JAC