[vorbis-dev] Decode questions
xiphmont at xiph.org
Wed Feb 16 14:50:41 PST 2000
> # cdparanoia -B 1-1
> # ./encoder-example < track01.cdda.wav > test.vor
> # ./decoder-example < test.vor > out.wav
> The rip and the encode both work fine. test.vor is 22280990 bytes (!)
I'm only adding the big residue compression now. I expect to have (at a
minimum) 128kbps streams this week.
> and track01.cdda.wav is 57998012 bytes long. decoder-example sez:
> Track encoded by encoder_example.c
> Bitstream is 0 channel, 0Hz
> Encoded by: Xiphophorus libVorbis I 20000121
Oop, sorry, I though I committed the fix for this... the residue header
unpacking is out of sync with the packing and the decoder example doesn't check
the return value.
> I haven't bothered to dig into the source to find out what is going on
> -- before I do that I wanted to inquire about the current status of the
> codebase in CVS. Should this work? Or is this a case of operator error?
No, CVS captian error. I committed a mildly broken version.
> Next, I dug into the source for decoder_example.c and I saw that in the
> decode cycle at the end the file does the double -> 16 bit unsigned int
> conversion as the last step, outside the decoder. Are there any plans
> to have the Vorbis synthesis layer take care of this step? I ask this,
> since this decoder/convert step moves the WAV data across the system
> bus a time more than is necessary. This could be avoided by simply
> carrying out the integer conversion before the decoded data is written
> to the output buffer.
That assumes that you always want the output in a specific, predetermined
format (like 16 bit interleaved stereo, particular endianness). OTOH, it's
pretty clear that most people will, in fact, desire 16 bit PCM in host
bytesex... so I guess I should add this, yeah.
> I also get the feeling that this might be jumping the gun a little bit.
Nope, you're right on schedule. I'm just a bit late as always.
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