[vorbis] retrieving "instant" bitrate without vo_open?

safemode safemode at speakeasy.net
Sat Sep 22 19:35:01 PDT 2001



On Saturday 22 September 2001 22:24, Michael Smith wrote:
> At 08:31 PM 9/22/01 -0400, you wrote:
> >ok, I'm aware that vo_open cant be used at the same time as other
> > functions such as ogg_sync_wrote, ogg_sync_pageout, ogg_stream_pagein,
> >ogg_stream_packetout and vorbis_synthesis_headerin.   In order to get
> >information from the bitstream i've been using this method because it's
> > fast and doesn't require decoding of the stream.  But, i can only
> > retrieve the average bitrate of the ogg stream with the vorbis_info
> > struct.  I tried using vo_open but could only retrieve garbage values and
> > it's because i basically dont know how to use it to do the same thing i'm
> > doing here.
> >
> >All i need to do is traverse the entire bitstream, take each packet and
> > look at it's individual bitrate.  Can i do this without vo_open or is
> > there a way to use vo_open and the ogg functions i've listed above ?  I'm
> > not aware of any way to set the vorbis_file struct to the current packet
> > without at least using vo_open and doing that ruins the ogg functions in
> > my tests.
>
> Why do you want to look at the bitrate of each individual packet?

http://psuedomode.homeip.net/mp3stat-1.9.tar.bz2   compile that and use the 
program to open 2 VBR mp3s.  it produces a linear bitrate graph of the mp3.  
I have preliminary ogg/vorbis support but as of now it only pretends that 
they're CBR.  Of course the reason why i want to look at each individual 
packet is to match up with mp3 output.  I could use JUST vorbisfile but i 
everytime i try it gives me random results because i'm probably using it 
wrong.  

> You can certainly do all of what you want without using vorbisfile. I'm
> not sure exactly what it is you want to do, though.

How could i do that without vorbisfile?  none of the other structures have a 
bitrate element.  That's the problem i'm having.  

> If you only want to make things work faster, try looking at ov_test(), and
> ov_test_open(). That might be an easier way to do it.

I just want to seek to each packet without processing anything and grab info 
about it.  

> Michael
>
>
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