Re: playing mp2 files
Re: playing mp2 files
- Subject: Re: playing mp2 files
- From: Stephen Davis <email@hidden>
- Date: Mon, 4 Sep 2006 11:04:19 -0700
On Sep 4, 2006, at 6:51 AM, David Duncan wrote:
On Sep 4, 2006, at 12:21 AM, Herbie Robinson wrote:
Well, Quicktime doesn't have a "standard" set of supported formats
either. All it has are plug-ins for everything. Mpeg-2, for
example is an option, not standard.
Still, it would be nice if Core Audio could figure out how to call
the Quicktime conversion plug-ins that are present. It would make
many development tasks easier.
Yeah, CoreAudio and QuickTime are two separate pairs of boots. I
wonder why CoreAudio doesn't simply support all formats that
QuickTime
does, this seems really inconsistent (and weird) to me.
Quicktime & CoreAudio do share codecs in the form of Audio Encoder
& Decoder (aenc & adec) components. However, Quicktime also
understands Sound Manager Encoders & Decoders, which CoreAudio does
not. So if a decoder is currently packaged as an sdec, then
Quicktime will be able to play the compressed stream back while
CoreAudio will not. Additionally, CoreAudio has it's own concept of
file format readers independent of Quicktime (although I think
Quicktime learned to use CoreAudio format decoders too) so it is
also possible that Quicktime knows how to decode a format that
CoreAudio does not.
Actually, CoreAudio's AudioConverter can now wrap many of the
SoundManager codecs as well. I don't remember which version added
this support but it was a while ago. David is correct about
QuickTime (7+) knowing how to use the AudioFile components such that
any supported AudioFile format should also be supported by QuickTime
(if it wasn't already). However, please note that I am not on the
QuickTime nor the CoreAudio team so I'm only speaking as a user. :-)
As for Herbie's second statement, QuickTime was developed loooong
before CoreAudio existed so it's only natural that there are some non-
overlapping regions of format/codec support. I imagine those
differences will lessen over time.
stephen
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