[mythtv-users] Re: nuvexport/transcode settings survey
for acceptable quality
mythtv at jonandtina.net
Mon Nov 29 00:25:59 UTC 2004
Gavin Hurlbut wrote:
>Jonathan Markevich <mythtv at jonandtina.net> wrote:
>>Well I've been experimenting a lot with the modules, and I get very good
>>quality out of using ffmpeg with the -b 1152 -vcodec mpeg1video -s
>>352x240 -hq -qmax 3 -qmin 13 -ar 44100 -aspect 4:3 and that gets me
>>about 300 MB per hour, while being fairly VCD compliant. I like this
>>very much because it encodes at 70-100fps.
>If it's 300MB/hr it's not even close to VCD compliant. VCD is about 600MB/hr
>and is fixed bitrate at 1150kbit video, 224kbit audio. If you calculate that
>out, that's nowhere near 300MB/hr.
Well, strictly true, but according to my DVD player, it is. It has
something to do with the -qmax and -qmin causing VBR on it. I'm still
not sure what the -b parameter does in this case (max?).
I've also read in a variety of places how the bitrate varies by one or
two... This one says "up to 1151" (http://www.digvid.info/media/vcd.php)
. This one says "1150" (http://www.videohelp.com/vcd) This one says
"1152" (http://www.covic.otago.ac.nz/doc/vcdtools/) and so does this one
(you have to search for it)
One important thing for me is to be able to open it in MPEG1 tools
(TMPGenc) and work with it. I want to make some things into KVCDs, and
some I want to mix together into quarter-DVD res DVDs (yeah, I have to
resample the audio for that). Nobody seems to care about MPEG1 anymore...
Another important thing is disk space, so, yeah, I'll give up strict VCD
compliance for that extra 300 MB. The third, and possibly most valuable
thing, is TIME. I would trade off the quality of mpeg2enc for the speed
of ffmpeg in a heartbeat (though, honestly, I don't really see much
I'm still working on it!
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