• 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: Synchronization problem in 10.2
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Synchronization problem in 10.2


  • Subject: Re: Synchronization problem in 10.2
  • From: Michel <email@hidden>
  • Date: Thu, 3 Oct 2002 23:53:24 +0100

On Thursday 03 October 2002 22:23, Mark Cookson wrote:
> You almost certainly need a buffer given to setSampleBuffer larger than
> 512 samples because most HAL clients use a buffer of that size, which
> means that there is no room for the erase head or your DMA hardware to
> read from. I'm sure the HAL would force a smaller buffer size on the
> clients, but I doubt that they really want to be working in buffers of
> 128 samples or less.
>
> IOAudioFamily is responsible for mixing the incoming streams of audio
> from each instance of the HAL. In my experience it is quite reliable
> in doing that. Are you overriding any of the more obscure
> IOAudioEngine or IOAudioStream functions? Like the ones dealing with
> the erase head or mixer? I can't think of a reason why two clients
> wouldn't work as well as one client.

The buffer size is limited due to IOMallocContiguous. I don't have a choice.
the bigger I allocate, the more chance there is for it to return addresses I
can't use.

What is "special" about what is happening in my driver is that I publish 8
channels to the IOAudioStream, but I have a different DMA setup. and I do the
black magic in clipOutputSample/convertInputSamples by completely ignoring
the buffer I had passed to the stream, and using instead the DMA one for
source/destination.

Thats the only way I found for masquerate the DMA layout. It works pretty
well, save from the mixing issues.
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.

  • Follow-Ups:
    • Re: Synchronization problem in 10.2
      • From: Mark Cookson <email@hidden>
References: 
 >Re: Synchronization problem in 10.2 (From: Mark Cookson <email@hidden>)

  • Prev by Date: Ann: Serial MIDI Interfaces
  • Next by Date: AU Drawing question
  • Previous by thread: Re: Synchronization problem in 10.2
  • Next by thread: Re: Synchronization problem in 10.2
  • Index(es):
    • Date
    • Thread