[vorbis-dev] Problems compiling Mac Libs

[Steve Nicolai]

>>> I then built the sample encoder and included the libs. I tried to encode a
>>> file and BOOM! Frozen Mac!
>> 
>> I've seen this with the release builds of the libraries.  I'm using the
>> debug versions which seem to work fine.  I've not taken the time to track
>> it down, it's on my TODO list though.
> 
> Can you get into Macsbug when it freezes? Is the heap corrupt? Are
> you allocating memory at interrupt time? Does turning on heap
> scrambling make it crash sooner?
> 
> If its a threading issue, you may find it easier to catch on X.
> 
I've got this one tracked down, it's a CodeWarrior optimizer bug.
You can't compile seed_chase() in psy.c with the global optimizer
at level 3 or 4.  The bug causes the function to smash the stack.
The bug is in both CodeWarrior 5.3 and 6.0.

> There isn't currently a way to make a VBR sound compression component
> in QuickTime. Existing ones (such as PureVoice) work by padding to
> the maximum length for a block, and then have the extra bytes
> stripped off by the packetizer before streaming or by the exporter
> before writing the output file. I'm not sure how amenable Vorbis is
> to this approach.

Is this stripping done in a generic way, or does the packetizer and
exporter have a list of codecs that it needs to do this for?  I.e.
how does the exporter recognize this and calculate the correct size?
Is it just returning an ExtendedSoundComponentData with the buffer
size filled in?  I'm just trying to save myself some time reverse
engineering how PureVoice does it.

> If you put the codebooks in a SampleDescriptionExtension, you should
> have a sensible upper bound on the packet length. There is brief
> discussion of truncating packets to fit a bitrate on the Vorbis
> website, but I don't know if this has been tried.

I'm planning on putting the codebook in a SampleDescriptionExtension,
so this mechanism is attractive to me.

The general concensus on peeling seems to be wait for chained
codebooks, it will be much easier.

Steve

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