Re: Reading the input level
Re: Reading the input level
- Subject: Re: Reading the input level
- From: Tom Jeffries <email@hidden>
- Date: Sun, 24 Feb 2013 21:14:13 -0800
I did some more tracing through, and discovered that the input callback is never called when the Tascam unit is selected. Given the fact that CoreAudio recording is usually done as pull vs push, I'm not entirely certain I know why the driver for the Tascam unit is being used to generate the callback. It seems to work well with other devices, but the Tascam unit uses its own USB Audio driver.
Any suggestions?
On Sun, Feb 24, 2013 at 12:00 PM,
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Today's Topics:
1. Reading the input level (Tom Jeffries)
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Message: 1
Date: Sat, 23 Feb 2013 13:12:57 -0800
From: Tom Jeffries <email@hidden>
To: "email@hidden Audio"
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Subject: Reading the input level
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I'm taking over some code to fix some problems, and one of them is baffling
me.
The application needs to monitor the input level and display it so that the
user can adjust if needed. The current code works perfectly with most
devices. Metering mode is enabled, and these two lines are called by a
timer routine and work- except with one device:
AudioUnitGetParameter(mMixerUnit, k3DMixerParam_PreAveragePower,
kAudioUnitScope_Input, 0, &levels[0]);
AudioUnitGetParameter(mMixerUnit, k3DMixerParam_PrePeakHoldLevel,
kAudioUnitScope_Input, 0, &peaks[0]);
When the selected input device is a Tascam US-144MKII, the value is always
-120 for both level and peak. There are a few differences with the Tascam
unit, for example, it lists 4 channels and has a safety offset of 0.
However, I don't see how either of those would cause this particular
problem. Right now my guess is that there is something in the USBAudio
drivers from Tascam that is doing things differently than expected.
Volumes do show up using Audacity, but if I'm reading the code correctly,
Audacity is using deprecated functions. Is it possible to run a separate
AudioQueue, not to capture the data, but simply so that I can grab the
input levels?
I appreciate your answers!
Thanks, Tom Jeffries
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