On Mon, 24 Apr 2000, Michael wrote:
>> You should remember that automatic compression of arbitrary audio signals
>> is not likely to result in structured audio but AAC/TwinVQ in MPEG-4.
>
>Is this already part of the MPEG4 standard?
Yes it is. Also remember that, like all MPEG standards, MPEG-4 isn't just
about audio coding. Its primary emphasis is on coding of multimedia, of
which audio is one part.
>> It is unlikely tat SA would be produced since the original data which is
>> compressed by these implementations rarely includes anything which could
>> be translated into SA sensibly.
>
>What about future posiblilities? What are your views on the paper
>"Generalized Audio Coding with MPEG 4 Structured Audio" by Eric Scheirer and
>Youngmoo Kim? Couldn't that be part of a MPEG4 codec in the future?
Very much so. But the coding strategy represented isn't really SA. It's some
yet to be conceived coding *implemented* in SA. There's a big
difference in that there is now no structure in the 'structured audio' we're
sending. To someone like me who's grown up to audio with trackers, such a
loss of structure is unfortunate. The primary area of application of SA is,
and will be, the coding of structured audio, something PCM signals simply
aren't.
>So SA was really never meant to be used for PCM audio coding?
Not primarily. That's why there are separate parts in MPEG-4 for precisely
that end. But, as the Schreier-Kim article displays, SA has a very wide
scope of applicability. It might in fact lead the way to a future of audio
coding where the coder is included or referred to in the audio stream
itself.
Sampo Syreeni <decoy@iki.fi>, aka decoy, student/math/Helsinki university
This archive was generated by hypermail 2b29 : Mon Jan 28 2002 - 11:46:39 EST