[vorbis-dev] Calculating vorbis packet durations...

[Adriano Almeida]

I had this problem and after a "few"searches I came to this method:

first decode and setup the ogg file until the point u find the modes
configuration.

If u have the previous page, save the granule postition.
while( !endOfPackets)
    {
    getPacket;
    check if this is and audio packet;
    read window configurations;
    thisPacketSize = previousPacketWindowSize/4+ thisPacketWindowSize/4;
    packetsGranule += thisPacketSize;
    realGranule = lastPageGranule+packetsGranule;
    }

if u want u can save packets granule inside a realgranule vector. I haven't
covered the case where the page is a continued page

<p>Hope it helps

<p>----- Original Message ----- 
From: "illiminable" <ogg at illiminable.com>
To: <vorbis-dev at xiph.org>
Sent: Tuesday, May 18, 2004 6:59 AM
Subject: [vorbis-dev] Calculating vorbis packet durations...

<p>> After a few other attempts at hacks to determine start times of pages, the
> only other option left is to partially decode the packets in the demuxer
in
> order to give correct start time stamps after a seek.
>
> Someone mentioned it was relatively easy to do without a full decode. I've
> had a bit of a search in the mailing lists and on the web and can't find
any
> details about it.
>
> What i need is to be able to calculate the duration of all complete
packets
> on a page such that i can subtract it from the end granule pos.
>
> Can someone point me to some psuedo-code or actual code of how to do this
?
> I assume the info needed is stored somewhere in the vorbis packet. I'm
also
> looking for the same information for speex also.
>
> Thanks
>
> Zen.
>
>
>
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