[vorbis-dev] Seeking ogg-vorbis

[Karthik Murthy]

Hi Rodrigo,

There are functions supported in the vorbis lib which do the required file
seek operations
with reasonable amount of performance..
The lib consists of a structure called the ov_callbacks which contains a
series of function pointers
which are made to point to the required file operation function during the
initialization process which is done through
a call to the ov_open function...

Yuo can try building the Ogg Vorbis SDK libraries on Microsoft VC++ as an
alternative and the libs do compile on this platform
successfully..

Hope this answers your question..Do get back if you have any queries on this
mail..

Regards,
Karthik Murthy..

-----Original Message-----
From: owner-vorbis-dev at xiph.org [mailto:owner-vorbis-dev at xiph.org]On
Behalf Of Rodrigo Gómez
Sent: Wednesday, July 23, 2003 5:01 AM
To: vorbis-dev at xiph.org
Subject: [vorbis-dev] Seeking ogg-vorbis

<p>Hi there.

I have been hearing to ogg vorbis for maybe 2 years and I can only say: it
is fantastic!

Right now, I'm working in a project that uses ogg vorbis as the format for
recording. I have now a working recording engine (I have recorded up to 8
channels at the same time and my computer uses only about 30% of the
processor, wich is great in this project), and I'm starting with the playing
engine.

I have seen the examples, but they are somewhat "simplistic" (no mean to
offense anybody!). I need to solve the following scheme:
    - The files I'm playing represent up to 24 hours of continuous
recording.
    - I need to decode the stream to a PCM memory buffer, that will be used
later by existing components to do the actual playing (this allows me to
display fancy graphics and so on).
    - I need to be able to seek to any position (seconds) in the file, and
it needs to be quick, and, most of all, needs to use low resources (I mean,
I can't decode the entire day into memory, for obvious reasons)
    - The files are recorded using the same parameters for all the file. I
mean, each file can have it's own sample rate, number of channels, and so
on, but it will be constant for any given file.
    - I just need to play one file at the time.

BTW: I'm using Borland C++Builder 6 to do this job, under Windows. I had
some trouble using the libs provided with the SDK, and I had to do an implib
from the DLLs. This is fine. The problem is: The libs are generated using a
calling convention that I don't use (and I can't use, because I have another
DLLs using different calling convention). Any idea of how to solve it? Is it
possible to recompile the SDK using Borland's tools? I'm sorry if this is a
"stupid" question, as I'm remembering now that I didn't checked the implib
help to see if it is something that can be changed here.

If someone can point me on the right direction to do this job it will be
terrific. I just need some real-world examples to see. A pseudocode will do.

Thanks, in advance.
And Thanks, for this great format.

Rodrigo Gómez

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