• Open Menu Close Menu
  • Apple
  • Shopping Bag
  • Apple
  • Mac
  • iPad
  • iPhone
  • Watch
  • TV
  • Music
  • Support
  • Search apple.com
  • Shopping Bag

Lists

Open Menu Close Menu
  • Terms and Conditions
  • Lists hosted on this site
  • Email the Postmaster
  • Tips for posting to public mailing lists
AUTimePitch + input notification
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

AUTimePitch + input notification


  • Subject: AUTimePitch + input notification
  • From: John Clayton <email@hidden>
  • Date: Mon, 15 Dec 2008 08:30:59 +0100

Hi All,

My goal is to sync up the sound being heard to the frames of video being displayed from a single QT movie. Sound is played via core- audio and can be pitch/rate shifted via an AUTimePitch - which makes the real progress through time variable (i do however know exactly when these rate changes will take place). The core-audio graph looks a bit like this:

QT Movie -> AUTimePitch -> Dynamics Processor -> Merge -> Output HAL

My thinking so far, is that the best (only?) unit of measurement would be 'number of frames processed' by the input callback of the AUTimePitch unit. In that way, I'd know how much data has been requested from the movie, but its uncertain how much data (and thus time latency) is introduced by the inner working of the AUTimePitch.

Is there a way to accurately work out the exact frame number of audio that is presently coming of the speakers assuming the chain above? If yes, then I can simply use that value + total number of frames in the movie to work out the right video frame that should be displayed (taking the graph and video display latency into effect as well at some point - but lets crawl first, run later).

Thanks
--
John Clayton
Skype: johncclayton




_______________________________________________ Do not post admin requests to the list. They will be ignored. Coreaudio-api mailing list (email@hidden) Help/Unsubscribe/Update your Subscription: This email sent to email@hidden
  • Follow-Ups:
    • Re: AUTimePitch + input notification
      • From: William Stewart <email@hidden>
  • Prev by Date: Re: IOAudioStream::clipIfNecessary() - Error???
  • Next by Date: Recognize signature change with CallHostMusicalTimeLocation
  • Previous by thread: AUSpeechSynthesis.component
  • Next by thread: Re: AUTimePitch + input notification
  • Index(es):
    • Date
    • Thread