Re: TimeStamp passed to RenderProc when using MusicPlayer
Re: TimeStamp passed to RenderProc when using MusicPlayer
- Subject: Re: TimeStamp passed to RenderProc when using MusicPlayer
- From: Philippe Wicker <email@hidden>
- Date: Thu, 17 Apr 2003 08:12:21 +0200
On Thursday, April 17, 2003, at 03:58 AM, Bill Stewart wrote:
Hello,
I should have asked a more specific question. I want to mix midi and
audio tracks and manage those tracks with the MusicPlayer. As a result
of a recent discussion about the need of a MusicPlayer callback, I've
decided to encapsulate the audio file reader in a dedicated AU and to
attach this AU to the track using MusicTrackSetDestNode. Now my problem
is to choose the better way to indicate to this AU what is the sample
"slice" to output at each call of the RenderProc, in particular when
the MusicPlayer is looping. To be more specific, I want the loop
locators to be modifiable in real time (while playing). I can use
"time" API to tell the MusicPlayer/MusicTracks how to loop on one hand,
and some parameters to tell the file reader AU what are the loop left
and right samples. To avoid race conditions which can occur when loop
is enabled or disabled when current sequence position is near the right
locator, I need to synchronize the changes. A convenient - and simple -
way would have been the sample time if it had reflected the loop
state. Looks like I have to find another solution :-(
Nope...
You can't make any of these assumptions.
The sample count just increments and in fact it would be really bad if
you tried to decrement it - if you want to loop, etc, then use either
the loop properties on the MusicTrack objects or the SetTime call on
the MusicPlayer
Bill
On Monday, April 14, 2003, at 10:17 PM, Philippe Wicker wrote:
Hi the list,
I'm wondering what is the expected behavior of the MusicPlayer
concerning the AudioTimeStamp value passed to AUs in the target
AUGraoh. In a recent thread, it has been said that 'mSampleTime'
field will allways be meaningful (from the HAL point of view). Can we
assume that this field starts from 0 when the MusicPlayer starts
playing? Can we assume that this field will reflects loop state (if L
is the sample time at left locator point, and R the sample time at
right locator point, then this field will periodically increase from
L to R, "drawing" a saw tooth curve)?
Thanks,
Philippe Wicker
email@hidden
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Philippe Wicker
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