[pvrusb2] Crashes fixed; more questions

[Phil Endecott]

Hi again,

I've made my NSLU2 crashes go away by disabling my NTP server.  It was a 
process of trial and error, made more complex by the fact that the 
crashes occur if the ntp server has ever run since boot.  In an earlier 
experiment I had stopped it, but that wasn't sufficient; is has to never 
have run.  So now I can get on with the real work, hence some more 
questions:

Audio: does "mute" remove the audio bits from the stream, or just reduce 
the volume to 0?  If the latter, is there a way to entirely remove those 
bits?  I have only one audio channel, which I can connect to either the 
L or R input on the PVRUSB2.  If I select "mono", which channel does it 
read?  Or does it average them?

VBR: If I set "variable video bitrate"=1, what happens?  Which of the 
"peak" and "mean" settings does it use?

"Signal present": it looks as if this only applies to the TV input; is 
there a way to detect signal present/absent for the composite input?

Now a more general MPEG question; this probably isn't the best place to 
ask this, so if anyone can suggest the right place, please go ahead.  I 
want to have about 3 processes reading the video stream coming from the 
PVRUSB2.  This isn't possible with the raw data because any readers 
after the first would be jumping in in the middle of the bitstream.  But 
it should be possible to have a "tee" process that reads from /dev/video 
and feeds it via sockets or pipes or whatever to various listening 
processes; it just needs to know where the groups-of-pictures start and 
ensure that each connection begins at one of these boundaries - I think, 
though maybe it is more complicated than that.  Does the driver know 
anything about the structure of the MPEG stream, or does it just get 
bits from the USB?  Assuming that it knows nothing, I need to parse the 
stream sufficiently to find the groups of pictures.  Does anyone know of 
something that can do this?  Can anyone suggest an MPEG parsing library 
that could be used to do this?  (There are various MPEG decoders out 
there, but I really only need to do the first bit of the parsing.)

Cheers,

--Phil.