OGG and Losslessness

[Voltage Spike]

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On Friday, October 18, 2002, at 09:19 AM, Bill Warner wrote:

> from the document that you provided I think this is more of a lossless
> compression only between the stereo channels.  Rather than throwing out
> stereo samples that it would normally deem unnecessary it would keep
> them.  The over all sound sample is still lossy.
>
> Although I don't know much about ogg, and that is just my 
> interpretation
> of the doc you sent to the list.

This was my interpretation as well.  It goes through a process ("stereo 
coupling" or something similar) where it examines the left and the 
right channel of the small sound sample it is working on.  If it deems 
that they are close enough in tone, then it will encode only one music 
channel and record the relative volume offset that should be applied 
when decoding.  From my experience, it determines that about 90% of the 
music I listen to can be combined in this way.

As someone else mentioned, FLAC or something else would be required for 
lossless compression.  Keep in mind, though, that blind listening tests 
have repeatedly revealed that people cannot tell the difference between 
a high-quality Ogg and the original source (even the medium quality 
setting is almost impossible to distinguish).  Lossless encoding is 
only required when the music is going to be edited ("remixing", etc.) 
since it is likely that the music will be encoded multiple times.

- -- 
                                                            Voltage Spike
       ,,,
      (. .)
- --ooO-(_)-Ooo--

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