[ogg-dev] liboggz and packets versus segments ...

[Warwick Baker]

I'm doing some work where narrowband speex audio capture is happening and
being written to file in the ogg container format. Later retrieval for
reading will occur too.



I've been using liboggz to do the file reading and writing and have
obviously come across some things I don't seem to follow or have just got
wrong.



I can happily generate an ogg file using liboggz with some test data.

I write the headers then pump a couple of 600 byte test data packets into it
and liboggz does the magic of breaking the 600 byte packet into 3 page
segments. Then I write an eos page to finish up.



I can then read this file back and rewrite it to another file and get
exactly the same result – which is great (result is test_with_data.ogg file
attached).



I then attempted to read back a sample spx file I obtained from the web
(attached female_scrub.spx) file.

I can read it back happily but I end up with a resultant file twice the size
as the read_packet callback gets called on each page segment being read, and
I am writing each of these back to the resultant file with a write feed and
they all end up on their own page (no matter how I set the flush flags).



The part I don't understand is why the read_packet callback only gets
invoked on my test file when the full 600 bytes have been read, noting that
it is written to file as 3 segments on the page (lengths, FF, FF and 5A I
think it was). But when the sample spx file gets read, the read_packet
callback gets called for each segment, which by the way are all of size 20
bytes, and returns only 20 bytes at a time.



Ideas?



Please forgive any obvious stupidity as I am a rank amateur with all this
stuff ;-)



Thanks,

Warwick Baker.
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