BbMPEG: Underflow

nicksteel · #1 07-12-2003, 11:27 AM

I am trying to mux a VCD (not SVCD) with BBMPEG. The video is a 352x240 CBR 1150 with M1 and MP2 output from TMPGEnc Wizard (DVD2AVI and Headache MP2 input). When I mux with BBMPEG, I get many, many underflow errors. This is when using either the MP2 from Headache or the MP2 from TMPGEnc. I have set:

Program stream type: VCD
VBR not checked
Pad not checked
Write program end code not checked
Add SVCD scan offsets not checked
Align sequence headers not checked
Computed Bitrate "Unused"
Forced mux rate 0
Pack options Size 2324
Packets/pack 1
Buffer Sizes
Video:46
Audio 1: 4
Audio 2: 4
Startup delays
Pack: 400
Video: 344
Audio 1: 344
Audio 2: 344

Any help?

jorel · #2 07-12-2003, 11:42 AM

why don't vbr and Write program end code ?

i'm asking cos really dont know in this case but....

this picture don't help you nicksteel my friend?
http://www.kvcd.net/forum/viewtopic.php?t=2224

nicksteel · #3 07-12-2003, 01:32 PM

Quote:

Originally Posted by jorel

why don't vbr and Write program end code ?

i'm asking cos really dont know in this case but....

this picture don't help you nicksteel my friend?
http://www.kvcd.net/forum/viewtopic.php?t=2224

Thanks, Jorel.

I solved the problem by setting force mux to 3528. This is not a VBR, but fixed at 1150 (std VCD).

J-Wo · #4 07-13-2003, 04:56 PM

Quote:

Originally Posted by nicksteel

I solved the problem by setting force mux to 3528. This is not a VBR, but fixed at 1150 (std VCD).

Could you explain what this setting means, nicksteel? I ask because elsewhere on this forum they suggest to set force mux to 0. I too have been having underflow errors lately but the mpgs burn and play fine. The one thing I have changed recently in my encodes is a setting in tmpgenc for VBV buffer size. By default it's 40 KB but I set mine to 0 (automatic). This supposedly solves random unexpected errors which crash the program.

J-Wo · #5 07-13-2003, 06:06 PM

Here are some of the errors I'm getting... Sometimes when I get only a few underflow errors the mpg plays fine in powerdvd. But once I got a whole slew of 'em and the second half the video was all choppy and not in sync with the audio.

Code:

Multiplexing video and audio:
 
  Scanning video stream for a sequence header ...
 
  Scanning video stream for pictures ...
  Found 157193 picture headers.
  Video stream information
    Stream length : 732319502
    Total time (seconds) : 5245
    Sequence start : 5475
    Sequence end : 1
    No. Pictures : 157193
    No. Groups : 5475
    No. I Frames : 5475 avg. size 22599 bytes
    No. P Frames : 47382 avg. size 5879 bytes
    No. B Frames : 104336 avg. size 3162 bytes
    No. D Frames : 0 avg. size 0 bytes
    Horizontal size : 528
    Vertical size : 480
    Aspect ratio : 1.0000
    Picture rate : 29.970 frames/sec
    Bit rate : variable
    Computed avg rate : 140000 bytes/sec (1120000 bits/sec)
    Computed max rate : 397550 bytes/sec (3180400 bits/sec)
    Vbv buffer size : 98304 bytes
    CSPF : 0
 
  Scanning audio stream for access units information
  Found 200788 audio frame headers.
  MPEG audio stream information
    Stream length : 104901486
    Syncwords : 200788
    Frames : 110638 size 522 bytes
    Frames : 90150 size 523 bytes
    Layer : 2
    CRC checksums : yes
    Bit rate : 20000 bytes/sec (160 kbit/sec)
    Frequency : 44.1 kHz
    Mode : 2 dual channel
    Mode extension : 0
    Copyright bit : 1 copyright protected
    Original/Copy : 1 original
    Emphasis : 0 none
 
  Multiplexing information
    Video stream data rate : 397550 bytes/sec (3180400 bits/sec)
    Audio stream 1 data rate : 20000 bytes/sec (160000 bits/sec)
    Overhead data rate : 5500 bytes/sec (44000 bits/sec)
    Total data rate : 423050 bytes/sec (3384400 bits/sec)
 
  Multiplexing file temp.mpg
    video PTS (4963702.00ms) underflow at pack 342672 by 0.19ms
    video PTS (5138443.23ms) underflow at pack 356229 by 0.72ms
    video PTS (5143681.80ms) underflow at pack 356788 by 14.90ms
    video PTS (5232637.33ms) underflow at pack 364112 by 4.42ms
    4 video underflows (SCR >= PTS or DTS)
 
    NOTE: The resulting file may not play back correctly.
    Try reducing the video bitrate or increasing the video and
    audio startup delays.
  Finished multiplexing temp.mpg

nicksteel · #6 07-16-2003, 12:20 PM

Quote:

Originally Posted by J-Wo

Quote:

Originally Posted by nicksteel

I solved the problem by setting force mux to 3528. This is not a VBR, but fixed at 1150 (std VCD).

Could you explain what this setting means, nicksteel? I ask because elsewhere on this forum they suggest to set force mux to 0. I too have been having underflow errors lately but the mpgs burn and play fine. The one thing I have changed recently in my encodes is a setting in tmpgenc for VBV buffer size. By default it's 40 KB but I set mine to 0 (automatic). This supposedly solves random unexpected errors which crash the program.

3528 is the mux rate that appears when you first install BBMPEG. I change to 0 for VBR encodes (forces BBMPEG to determine best mux rate), but find that this causes underrun errors when processing CBR encodes. Even this doesn't work in all cases.

dazedconfused · #7 07-16-2003, 01:30 PM

Quote:

Originally Posted by J-Wo

The one thing I have changed recently in my encodes is a setting in tmpgenc for VBV buffer size. By default it's 40 KB but I set mine to 0 (automatic). This supposedly solves random unexpected errors which crash the program.

I'm pretty sure I remember Kwag saying long ago that he chose 40 as kvcd's VBV buffer size after determining that it was more compatible with more dvd players (in other words, going too high or low with this value can lead to playback problems sometimes). I also think he mentioned that using 0 and letting TMPG determine the value for you wasn't the greatest idea because it often led to problems. Perhaps he will see this post and jump in here to explain it better for you. (or you can search through his old posts).

Personally, I've tried this trick too and ran into the same muxing problems as you with underflows when using 0 vbv buffer (although the files still played back fine, possibly because they were only ~20minutes long...or maybe my dvd player just handles vbv-issues well). I've really only used this 0-vbv trick on a few fullscreen anime/cartoon encodes because those seem to cause illegal decimal problems often for me (I think I've only ran into maybe 1 or 2 instances when a regular widescreen film gave me an illegal floating decimal point error!).

My only suggestion would be to not use the 0 vbv buffer setting unless you really need to (even though this "trick" seems to always result in a successful encode, wheras other "tricks" listed here might not!

) . If you do use 0-vbv, you might also try muxing with TMPG instead of BBMPEG to see what happens, if you haven't already tried this (although there's a reason why BBMPEG is the recommended muxer here....more people report more problems with TMPG-muxed files on their dvd players...so I wouldn't hold my breath that TMPG's muxing will be the solution).

I've also found that sometimes just bumping up the vbv by 2 measely points results in a successful encode, while other times I needed to use 60vbv or even higher on some files.

It certainly isn't fun playing the guessing-game, and I can sympathize with you, that's all I know!

Good luck.
-d&c

jorel · #8 07-16-2003, 01:40 PM

maybe my new tests with references using BBmpeg and Tmpgenc,
help a little too,see my results:

http://www.kvcd.net/forum/viewtopic.php?t=4193

ps:
read my last test using Tmpgenc!