[mythtv-users] nuvexport - drastic quality difference
skd5aner at gmail.com
Mon May 14 22:12:13 UTC 2007
On 5/14/07, Matt <skd5aner at gmail.com> wrote:
> On 1/11/07, Chris Petersen <lists at forevermore.net> wrote:
> > Christopher Friend wrote:
> > > I noticed this problem a couple of months ago while I was putting the
> > > nuvexport page up on the mythtv wiki. Up until that point, ffmpeg
> > > transcodings were fine, no real noticeable quality difference from
> > > transcode. But since then it's had, like you describe, horrible
> > > artifacts in the image regardless of what options I choose (eg. encoding
> > > at 900 kbps ends up looking like a >100 kbps vid at points).
> > >
> > > I assumed it was a bug with ffmpeg and as i rarely use it anyway then
> > > I've not been bothered by it. But it explains why there's no transcode
> > > vs. ffmpeg visual comparisons in the wiki. and also any screen shots of
> > > dvd type codecs as transcode won't let me use it for that kind of thing...
> > Have you perhaps upgraded ffmpeg to a newer version of svn without
> > upgrading nuvexport, too? ffmpeg recently changed the commandline
> > parameter for setting the bitrate, so it's quite likely that your
> > recordings are getting set to ffmpeg's minimum bitrate (you should try
> > doing the math on the file sizes).
> > -Chris
> I'm currently running current FFMPEG SVN and nuvexport SVN, still
> choppy. Looks pretty bad. I guess I'll resort to using transcode
> versus ffmpeg. Can you get good quality xvid's by using ffmpeg
> yourself today?
Figured I ought to show what I get in debug mode:
Use the following commands:
mkdir -m 0755 /tmp/fifodir_14477/
/usr/bin/nice -n19 /usr/local/bin/mythtranscode --showprogress -p '0'
-c '1005' -s '2006-05-27T22:30:00' -f "/tmp/fifodir_14477/"
/usr/bin/nice -n19 ffmpeg -y -f s16le -ar 48000 -ac 2 -i
/tmp/fifodir_14477/audout -f rawvideo -pix_fmt yuv420p -s 480x480
-aspect 1.33333333333333 -r 29.970 -i /tmp/fifodir_14477/vidout
-aspect 1.33333333333333 -r 29.970 -deinterlace -croptop 24
-cropright 24 -cropbottom 24 -cropleft 24 -s 512x384 -vcodec xvid -b
'786432' -bt 32 -minrate 32 -maxrate 1536 -bufsize 65535 -flags
+4mv+trell+loop -aic 1 -mbd 1 -cmp 2 -subcmp 2 -cgop 1 -b_qfactor
'150' -b_qoffset '100' -bf '1' -qmax 31 -qmin 3 -acodec mp3 -async 1
-ab 128 -f avi './Saturday Night Live.avi' 2>&1
Cleaning up temp files.
then here is the ffmpeg output:
FFmpeg version SVN-r8880, Copyright (c) 2000-2007 Fabrice Bellard, et al.
configuration: --enable-shared --enable-gpl --enable-pp
--enable-dc1394 --enable-liba52 --enable-liba52bin --enable-libdts
--enable-libfaac --enable-libfaad --enable-libfaadbin --enable-libgsm
libavutil version: 49.4.0
libavcodec version: 51.40.4
libavformat version: 51.12.1
built on May 3 2007 17:08:30, gcc: 4.1.2 (Ubuntu 4.1.2-0ubuntu4)
Input #0, s16le, from '/tmp/fifodir_14477/audout':
Duration: N/A, bitrate: N/A
Stream #0.0: Audio: pcm_s16le, 48000 Hz, stereo, 1536 kb/s
Input #1, rawvideo, from '/tmp/fifodir_14477/vidout':
Duration: N/A, bitrate: N/A
Stream #1.0: Video: rawvideo, yuv420p, 480x480, 29.97 fps(r)
Output #0, avi, to './Saturday Night Live.avi':
Stream #0.0: Video: xvid (hq), yuv420p, 512x384, q=3-31, 786 kb/s,
Stream #0.1: Audio: mp3, 48000 Hz, stereo, 0 kb/s
Stream #1.0 -> #0.0
Stream #0.0 -> #0.1
Press [q] to stop encoding
frame= 1659 fps= 15 q=31.0 Lsize= 13495kB time=55.3 bitrate=1998.3kbits/s
video:12525kB audio:866kB global headers:0kB muxing overhead 0.775130%
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