• 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
Re: audio sync problem
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: audio sync problem


  • Subject: Re: audio sync problem
  • From: Greg Chapman <email@hidden>
  • Date: Thu, 16 Jun 2005 09:59:14 -0700

Are you sure that your QuickTime sourcing code is producing synchronized data (ie. does the first buffer from src1 contain the same samples as the first buffer from src2, when you feed them both from the same content)? That would be my first guess...

What method does your QTSoundFilePlayer use to get audio from QuickTime? Is it PutMovieIntoTypedHandle, or is it GetMediaSample followed by a SoundConverter? Or is it something else?

Greg Chapman
QuickTime Engineering

On Jun 16, 2005, at 1:50 AM, Guillermo Lapresta wrote:

Hi all,

I'm building an app which mixes various audio streams. The source of each stream is QT (a modified QTSoundFilePlayer), then passed to three param EQ, then are mixed with a 3DMixer and the result finally go through a dynamics processor and to the default output. A simple diagram:

  Src 1 -> EQ ->
                            -> 3DMixer -> Dynamics -> Out
  Src n -> EQ ->

The problem: Let's suppose we have a sound in src1 and the same sound in src2. The result is that the mixed stream is not the desired (the sound amplified and eq'd), it is mixed with a strange *random* latency so a weird delay effect appears. I've verified that there are no buffer underruns, and that in my render callbacks the audio is served at a exact position of mSampleTime.

I've tried shrinking the buffers of the audio units with no result. Can anyone give me a pointer of what's happening? In theory, 3DMixer pulls from each of its inputs and when it has a something to mix from each of them, it mixes it, doesn't it?

Thanks in advance, and sorry for my bad english.

_______________________________________________
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


_______________________________________________ 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: audio sync problem
      • From: Guillermo Lapresta <email@hidden>
References: 
 >audio sync problem (From: Guillermo Lapresta <email@hidden>)

  • Prev by Date: Multiple unexpected AudioConverterComplexInputDataProc invocations
  • Next by Date: Acquiring input Data
  • Previous by thread: audio sync problem
  • Next by thread: Re: audio sync problem
  • Index(es):
    • Date
    • Thread