Errors in Local File Output

Van der Westhuisen Chris chrisvdw at sentech.co.za
Wed Aug 21 08:13:54 CEST 2002


Hi Benoit,

Thanks very much for your response.  What I mean with the file not
containing pure transport packets, is that sometimes the file contains
packets of 188 bytes, each starting on a 0x47 sync byte, and then suddenly
in some cases I've seen sometimes one byte, sometimes three bytes before the
next 0x47.  The equipment I'm using to try to play the recorded file assumes
the file is correct 188 byte packets and does not try to re-sync.

It would be kind of hard to cut out sections of files to send you.  I will
send you (privately) my packet viewer, so you can yourself stream to files
and view them to see if they are correct.

By the way, I think I should mention I'm compiling vls-0.3.3.tar.gz on my
Linux machines and using vls-0.3.3-win.zip on Windows.  I don't know about
this CVS stuff and probably can't use CVS from behind our firewall.

Regards,

Chris

-----Original Message-----
From: Benoit Steiner [mailto:benny at via.ecp.fr]
Sent: Wednesday, August 21, 2002 4:48 AM
To: vls-devel at videolan.org
Subject: Re: Errors in Local File Output



Some simple maths seem to indicate that the Alpha and the Pentium 3 did
not flush completely their buffers before exiting (188 is the size of a
TS packet):

12 373 972 - 12 373 972 % 188 = 0
12 373 972 - 11 026 388 % 188 = 0

The numbers don't add up on windows but the file size is often "weird"
on this plateform. This would explain the problem of the size of the
packets. Can you explain what you mean exactly by "the output file never
contained pure transport packets" ? Can you send the equivalent of a few
TS packets for inspection ?

Benoit


> Van der Westhuisen Chris wrote:
> 
> Hi Guys,
> 
> I am working in a DVB environment. My final aim is to write an
> application to capture the TS output from VLS and stream it out on an
> ASI output card.  So my first step was to "record" a file in TS format
> using the Local File option.
> 
> I had problems with this right from the start as the output file never
> contained pure transport packets and mostly obviously too small.  Last
> night, however, I tried to stream the same file I used before using a
> 486 running Slackware Linux 8.1.  The output was perfect (bigger than
> the .vob file as I would expect).
> 
> So I streamed the same file this morning on different machines. It is
> a .vob file, size 11 268 096 bytes.  Here are the results:
> 
>         486 Linux       12 373 972 bytes ("correct")
>         AlphaServer running Linux 12 373 972
>         Pentium III running Linux 11 026 388
>         Celeron running Windows   11 322 166
> 
> I hope you can shed some light on this!  I have a Transport Packet
> Viewer I wrote (Windows only unfortunately).  Let me know if any of
> you (VLS developers) wants it.
> 
> Thanks,
> 
> Chris van der Westhuizen
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