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[vdr] Re: [PATCH] (DVB-T) statmux fix vbr tagging for pic header



At 10:43 15/05/2003, you wrote:
Well - actually in MPEG1 0xFFFF is used to mark a stream as variable
bitrate.
Due to an older version of the standard that I used when writing the first
version
of PVAStrumento, I kept this nomenclature for MPEG2....

With MPEG2 the standard really does not differentiate between CBR and VBR
anymore....
_but_ a value of 0xFFFF for VBV-Delay puts the decoder buffer in a different
method
of operation (which makes it essentially not look at vbv-delay values).
Hi Wiljo, thanks for commenting so quickly. I found http://www.eee.metu.edu.tr/~alatan/PAPER/icip.00.pdf which comments on those to modes, and explains regarding VBR: "In VBR VBV model, data always enters VBV at Rmax, if the buffer is not full. When the buffer is full, no data enters the buffer".

Maybe sth. like that happens, so setting vbv_delay to 0xFFFF will heal the
decoder.
I don't know.The linux driver ppl. should have a look at this.
How do you detect whether a stream is VBR in PVAStrumento? Do you look at bitrate changes between headers - but then again those could be set to CBR as you point out in the helpfile. Does this mean when "Flag Stream as variable Bitrate stream" is set it always sets the vbv_delay to 0xFFFF even for proper CBR files? I take it, it can't have a negative impact for the decoder then (as underflows are allowed but not overflows)?

On a the same note: I've submitted this over on linux-dvb and hope for some fruitful discussion on this:
http://www.linuxtv.org/mailinglists/linux-dvb/2003/05-2003/msg00209.html

Thanks for the flowers ;-) You should mention that (the Helpfile....) to the
german-only-speaking
users :-/
You're welcome. I know what you mean, I'm sure you get lots of support mail, that can be quite a drag I guess.

All the best,
Gregor


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