[mythtv-users] nuvexport ffmpeg video quality

[Paul Gardiner]

On 11/05/2011 08:20, Joel Ebel wrote:
> For reference, these are the ffmpeg and mencoder commands that nuvexport
> generated:
>
> ffmpeg -threads 4 -y -f s16le -ar 48000 -ac 2 -i
> /tmp/fifodir_20851/audout -f rawvideo -pix_fmt yuv420p -s 1280x720
> -aspect 1.77777777777778 -r 59.940 -i /tmp/fifodir_20851/vidout -aspect
> 1.77777777777778 -r 59.940 -s 624x352 -vcodec libxvid -b 1024k -minrate
> 32k -maxrate 2048k -bt 32k -bufsize 65535 -flags +mv4+loop+aic+cgop
> -trellis 1 -mbd 1 -cmp 2 -subcmp 2 -b_qfactor 150 -b_qoffset 100 -bf 1
> -qmax 31 -qmin 4 -acodec libmp3lame -async 1 -ab 128k -f avi
> /mnt/storage/videos/The Simpsons - The Devil Wears Nada.avi
>
> mencoder -aspect 1.77777777777778 -noskip -idx /tmp/fifodir_13604/vidout
> -audiofile /tmp/fifodir_13604/audout -demuxer 20 -audio-demuxer 20
> -rawaudio rate=48000:channels=2 -demuxer 26 -rawvideo
> w=1280:h=720:fps=59.940 -ovc xvid -oac mp3lame -lameopts vbr=3:br=128
> -xvidencopts fixed_quant=4 -o /mnt/storage/videos/The Simpsons - Pranks
> and Greens.avi -vf scale=624:352

If you're looking into the inner workings of nuvexport then maybe you
know more about mythtranscode than is available in it's documentation.
I assume, for each command above, mythtranscode is running in
parallel, sticking raw video and audio in the pipes. Would be great
if you could answer a couple of questions.

1) mythtranscode typically replaces its source file with the
transcoded version. Does it still do that when --fifodir
is specified?

2) Is it always raw video and audio that is output to the fifos, or
does that depend on the profile specified? If it is always
raw then does the profile have any affect on what is produced?

3) Do you know the specific transcode calls that coresponded
to the encoder commands above?

Cheers,
	Paul.