Re: Using virtual Memory on a sample player in AU
Re: Using virtual Memory on a sample player in AU
- Subject: Re: Using virtual Memory on a sample player in AU
- From: Philippe Wicker <email@hidden>
- Date: Sat, 3 Jan 2004 09:24:37 +0100
On Saturday, January 3, 2004, at 05:30 AM, Cyril Blanc wrote:
Ciryl,
Thanks for your wishes. My turn to wish you and to all people in this
list a happy 2004 year.
Hello
I wish you all ; all the best for 2004.
I use a product called .. (I will not name it because I do not want to
put
too much shame on this company)
The programmer from that company does not seem to manage to write a
virtual
memory handler for there sampler using Audio Units.
Is there is somewhere a document/source code that could help them.
When dealing with large samples, a good approach is to stream them from
disk instead of loading them entirely in memory. The basic idea is to
read chunks of the sample file according a ping/pong scheme. The first
chunks of samples that may be used in a give song should be resident in
memory in order to guarantee a short latency when the note-on events
(StartNote) occur.
I don't know of any documentation targeted on that specific topic, nor
of complete ready-to-use disk streaming sample player source code. Some
partial answers are available here and there. I know of 3 sample codes
dealing with reading a file chunk by chunk: FileAudioPlay (C++) in the
CoreAudio SDK, PlayBufferedSoundFile (Obj C) written by Kurt Revis (
www.snoize.com ), and FilePlayer (C++) that can be found on my site (
http://homepage.mac.com/pwicker ). This last sample includes code to
manage looping between arbitrary left and right locators.
When the work on my main project (the Audio IPC SDK) leave me some
time, I work on a sample player based on disk streaming. You may give
my email address to this programmer, I'd be glad to share my experience
with him.
Thanks in advance.
Best regards
Cyril Blanc
France
If you want to be sure I read your answer leave my name in it !
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Philippe Wicker
email@hidden
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