[directmusic] Re: Compression: ADPCM?
- From: "Bjorn Lynne" <bjorn@xxxxxxxxxxxxxx>
- To: <directmusic@xxxxxxxxxxxxx>
- Date: Wed, 12 Mar 2003 13:39:09 -0000
Hi Paul,
> Anyone know if there is anything else that will compress my wavs into
ADPCM
> format other than DMP?
>
> I've heard that this compression can sound a bit grainy or slightly harsh,
> but an external editor, like wavelab, might be able to render my files a
> touch more elegantly.
You can save out ADPCM from SoundForge, but don't expect any miracles. ADPCM
compression sounds great with *most* sounds, but a few sounds will sound
very gritty and harsh, no matter which program performed the compression.
> I was tempted to go the mp3 route, but this 2.1 second thing sound like a
> real pain - is it DMP that adds the glitch on play back? If you encode in
an
> external editor and replace the runtime files, it must be in the play back
> that the glitch occurs.
I'm not sure if you are talking about the little bit of silence added to the
beginning and end of the mp3 file, making it unsuitable for sounds that need
to start immediately, or looping sounds... but this is a weakness of the mp3
file format. I investigated this a lot a couple of years ago (including
communicating directly with one of the guys at Frauhofer who made the
format), and there is apparently no way to create mp3 files that don't have
this little bit of silence at the beginning and end... making mp3 unsuitable
for looping or low-latency playback.
Actually, there is ONE program that does seem to make it possible: Flash. If
you import a WAV file into Flash and set the compression to "mp3
compression" inside Flash, then you can save out your Flash movie, which
will include an embedded mp3, which *will* loop smoothly in Flash Player.
I'm guessing that this is because Flash has compressed to mp3 itself, it
knows exactly how much silence has been added to the beginning and end, and
is able to skip these parts when it plays back.
> Is any of these compression formats more CPU friendly on decode?
I believe mp3 is a great deal more CPU intensive than ADPCM. Somebody
correct me if I'm wrong.
Cheers,
--
Bjorn Lynne - Composer, Producer, Sound Designer
Main music site: www.lynnemusic.com
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