[MPlayer-users] Re: Unknown block type, possibly non-MPEG stream!

Dominique De Munck chef at ulyssis.org
Mon Apr 12 20:22:41 CEST 2004


I don't know what you mean by "normalizing", but I realy dislike indexing
my 2+ GB  avi recordings  each
time I want to scroll them. So having a nice mpeg output would be great.

Some more info about this anoying problem:

When capturing TV to the mpeg format with mencoder (cvs, 10 April), I get

Unknown block type, possibly non-MPEG stream!
Unknown block type, possibly non-MPEG stream!

I don't know why, but changing the channel on my VCR triggers 1 such
I get them about 25 times / hour in normal tv show, even when I adjuist
such that I get CPU usage around 20%.

Audio sync with mplayer is OK, but not with ffmpeg, transcode, mplex, ...
(which I need to get it on DVD)
There in the resulting file  audio video sync has problems: video runs
faster, +/- 1 sec / hour .

When I "cut" some some fragments with "ovc copy avc copy", mencoder
reports :

1 duplicate frame(s)!

about as many times as I get that error and the resulting file is OK with

I  record like this:
mencoder -quiet tv:// -tv
ovc lavc -of mpeg -lavcopts
-channels 1 -oac lavc \
-vop crop=712:568:4:4 -o dvd2004_04_04-13_30_12.mpg

An example file  with 1 such error in can be found at

The errors comes from the following code :

  if (s->type == MUXER_TYPE_VIDEO) { // try to recognize frame type...
    if (s->buffer[0] != 0 || s->buffer[1] != 0 || s->buffer[2] != 1 ||
len<6) {
      printf ("Unknown block type, possibly non-MPEG stream!\n");

in libmpdemux/muxer_mpeg.c line +/- 255

Badly enough, I can't give an example file where "mencoder" corrects the
"bad frames" because it occurs only with files > 200 MB.

Some more info can be found  at :


Dominique De Munck

>no, I didn't find a solution, but I figured out a couple of workarounds.
>It seems that "-of mpeg" simply does not work when normalizing frame
>because all duplicate frames result in this error (I guess the block type
>of duplicate frames is not set correctly). So there are following

>1. Don't use "-of mpeg" when normalizing frame rate. If you need mpeg,
>   convert the resulting avi back to mpeg (which of course causes some
>   quality loss).
> 2. Buy a better videoconverter (Hauppauge sucks!) that has the "locked
>   audio" feature, so the frame rate will be exact and don't need
>   normalizing.
> Andres.

> On Sat, 10 Apr 2004, Dominique De Munck wrote:

> Hi,
> I read your poste on Mplayer maillinglist.
> Have you found a solution for that problem already ?
> Even in CVS version of today I'm still heaving that problem.
> bye,
> Dominique
> --

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