Hello,

When rendering DV to DVD-MPEG from within Cinelerra, I use the following
pipe for video rendering:

yuvcorrect -v 0 -T INTERLACED_BOTTOM_FIRST | mpeg2enc -M 2 -v 0 -r 32 -4
1 -2 1 -D 10 -g 15 -G 15 -q 5 -b [bit_rate] -f 8 -o %


I use a bit rate from 9600 on downwards, depending on the video noise
and detail, to keep the absolute maximum bit rate below 10,000 kbps.

Occasionally however, even mpeg2enc bit rates as low as 8600 kbps (with
a maximum of some 9750 kbps, see below) result in problems with
DVDstyler/mplex. Here's what I hope is the relevant output (file names
simplified):

...

Check MPEG-files
Make Vob-file from 'movie.m2v' and 'movie.ac3'
   INFO: [mplex] mplex version 1.8.0 (2.2.4 $Date: 2005/08/28 17:50:54
$)
   INFO: [mplex] File movie.m2v looks like an MPEG Video stream.
   INFO: [mplex] File movie.ac3 looks like an AC3 Audio stream.
   INFO: [mplex] Video stream 0: profile 8 selected - ignoring
non-standard options!
   INFO: [mplex] Found 1 audio streams and 1 video streams
   INFO: [mplex] Selecting dvdauthor DVD output profile
   INFO: [mplex] Multiplexing video program stream!
   INFO: [mplex] Scanning for header info: Video stream e0 (movie.m2v) 
   INFO: [mplex] VIDEO STREAM: e0
   INFO: [mplex] Frame width     : 720
   INFO: [mplex] Frame height    : 576
   INFO: [mplex] Aspect ratio    : 4:3 display
   INFO: [mplex] Picture rate    : 25.000 frames/sec
   INFO: [mplex] Bit rate        : 8600000 bits/sec
   INFO: [mplex] Vbv buffer size : 229376 bytes
   INFO: [mplex] CSPF            : 0
   INFO: [mplex] Scanning for header info: AC3 Audio stream 00
(movie.ac3)
   INFO: [mplex] AC3 frame size = 512
   INFO: [mplex] AC3 AUDIO STREAM:
   INFO: [mplex] Bit rate       :    16384 bytes/sec (128 kbit/sec)
   INFO: [mplex] Frequency      :     48000 Hz
   INFO: [mplex] SYSTEMS/PROGRAM stream:
   INFO: [mplex] rough-guess multiplexed stream data rate    : 8911296
   INFO: [mplex] target data-rate specified               : 10080000
   INFO: [mplex] Setting specified specified data rate: 10080000
   INFO: [mplex] Run-in Sectors = 89 Video delay = 13019 Audio delay =
16619
   INFO: [mplex] New sequence commences...
   INFO: [mplex] Video e0: buf=      0 frame=000000 sector=00000000
   INFO: [mplex] Audio bd: buf=      0 frame=000000 sector=00000000
++ WARN: [mplex] Stream e0: data will arrive too late sent(SCR)=25904274
required(DTS)=25904219
++ WARN: [mplex] Video e0: buf=  76978 frame=007192 sector=00137301
++ WARN: [mplex] Audio bd: buf=  14269 frame=009016 sector=00002290

   INFO: [mplex] Scanned to end AU 16767
   INFO: [mplex] STREAM e0 completed @ frame 16767.
   INFO: [mplex] STREAM bd completed @ frame 20959.
   INFO: [mplex] Multiplex completion at SCR=60298093.
   INFO: [mplex] Video e0: buf= 158266 frame=016767 sector=00313454
   INFO: [mplex] Audio bd: buf=  14336 frame=020959 sector=00005324
   INFO: [mplex] VIDEO_STATISTICS: e0
   INFO: [mplex] Video Stream length:   633600118 bytes
   INFO: [mplex] Sequence headers:     1118
   INFO: [mplex] Sequence ends   :        1
   INFO: [mplex] No. Pictures    :    16768
   INFO: [mplex] No. Groups      :     1118
   INFO: [mplex] No. I Frames    :     1118 avg. size 64212 bytes
   INFO: [mplex] No. P Frames    :    15650 avg. size 35898 bytes
   INFO: [mplex] No. B Frames    :        0 avg. size     0 bytes
   INFO: [mplex] Average bit-rate :  7557200 bits/sec
   INFO: [mplex] Peak bit-rate    :  9751600  bits/sec
   INFO: [mplex] BUFFERING min 15 Buf max 235543
   INFO: [mplex] AUDIO_STATISTICS: bd
   INFO: [mplex] Audio stream length 10731520 bytes.
   INFO: [mplex] Frames         :    20960
   INFO: [mplex] BUFFERING min 35 Buf max 7299
**ERROR: [mplex] MUX STATUS: Frame data under-runs detected!

Error executing of command: mplex -f 8 -b 230 -o "dvd/title0-0-0.vob"
"movie.m2v" "movie.ac3"




I don't quite understand what's going wrong here; I can't see anything
special at the indicated video frame time (frame 7192, 0:04'47"). In
fact, I don't quite understand what this "data arriving too late" and
those SCR and DTS values mean; I found that these values remained the
same, regardless of the encoding bit rate. Also, the peak bit rate stays
well below 10,000 kbps, so that shouldn't be a problem.

Does someone know what's happening here? And, of course, any suggestions
for a solution are highly appreciated, since a) I can't seem to create a
DVD from a simple, 11-minute piece of DV, and b) rendering takes an hour
and a half, even on a dual-core AMD64 machine (and as you can see, I
already used the -M 2 option with mpeg2enc).

Are there ways or tools to predict these types of problems? It's a bit
frustrating to see mplex stumble and fail after 90 minutes of rendering,
and not just once, but four times in a row now - and without any way of
knowing which settings will work. 
I have encoded other video fragments of the same duration with peak bit
rates of up to 9900 kbps without any problem whatsoever, so this is
rather puzzling ...

Thanks so much in advance,

Regards,

Richard Rasker


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