Latency Issue
Latency Issue
- Subject: Latency Issue
- From: <email@hidden>
- Date: Thu, 29 Jan 2004 19:08:56 -0500
Hi all,
I have a question about the latency issue. Here is the situation:
I am developing an audio input driver for a PCI device. Due to the hardware limitation, the dma transfer to the audio stream buffer 4K at a time and the currentSampleFrame will be updated accordingly. I have the ring buffer 16K large so there would be 4 DMA before reaching end of the ring buffer. When the last DMA chunk finished by a hardware interrupt callback, the takeTimeStamp() will be called.
When i do a software playthru test to play back the captured audio data, i found that there are significant latency happened to the audio signal when i compare with the hardware playthru output from my input device. I have looked into one of the archives
http://lists.apple.com/archives/coreaudio-api/2003/Jun/17/fismixable.017.txt memtioned here, but seems like it didn't solve the problem. changing the setSampleLatency() value didn't seems to help. So what's wrong with my setup and which area i should look into to fix it?
I also found that if i do software playthru using Sequence Grabber from QT, it would have a much larger latency when playback. Is there something i missed in the setup? How can i correct this problem?
Thanks for your help
Eric
1
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