How to force digital input sample rate?

Does anyone know how to force a Digital Input sample rate and/or tell Core Audio which conversion clock to use... internal or external? Apparently both things can be done from Pro Tools, but I don't have it. My problem is locking onto an A/D converter's 48K Toslink output. I can set 48K in 'Audio - Midi' setup and the audio is perfect, but a few seconds later Core Audio returns to the default 44.1K. I need to force it to stay at 48K, or clock on the signal rather than internal clock.

Braver,
Let me clarify a few things. First, the 6733 supports correlated digital I/O. This means that the digital operation does not have its own clock. You can correlate the digital operation with the AO clock, which will allow a digital operation up to the max AO rate. You can generate a pulse train with an onboard counter and use that as your digital clock source. Also, you can use a completely external clock source to achieve the max digital rate of 10MHz. The knowledge base, linked below, points you to a couple of examples that ship with LabVIEW. Be sure and read the documentation associated with each example.
Knowlege Base
As for
the example CDI Single Point clocked by Counter (E).vi, notice how the output of...

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Anyway to force a Digital Input sample rate?

I've tried three different A/D converters and all fail on the Mac Pro, but work with other equipment. All of the A/D converters have a fixed 48k output sample rate. I can set a 48k sample rate on the Mac and the sound's great. Unfortunately, it only holds this setting for a few seconds, then snaps back to a 44.1k sample rate and says 'locked'. The audio is then slow and distorted.. like playing a 45 rrmp record at 33 1/3 rpm. My question is, is there any way I can stop OSX from falling back to 44.1k; i.e. force it to hold the 48k sample rate?

Got an updated Core Audio driver from Digidesign - that fixed it.

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Try to use:
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How to sync. 50Hz sample rate with 5Hz external digital trigger signal?

Hello there,
I want to sample an analog input at 50Hz, where I further want to use
the 5Hz PPS signal of a GPS receiver as an external trigger/clock
signal for the NI DAQ USB-6008 device. However, I do not want to read
10 samples every 200ms (= 50Hz avg. sample rate), but I want to read 1
sample every 20ms, i.e. with "real" 50Hz.
The "natural" way, it seems would be to use a task that waits for a
rising edge on the ext. trigger input, then reads 10 samples, then
waits for the next trigger edge, and so on.
However, it seems that with this approach I cannot read the data from
the DAQ with real 50Hz, further it seems that every 10 samples the task
needs to be restarted, which takes longer than the 20ms (corresponding
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I hope the problem description is clear enough....
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You have to use the counter together with the analog input to achive this. You could configure the counter to generate 10 pulses with 50 Hz whenever the counter sees a rising edge on the inpput of the counter. The output of the counter would be used as the external clock for the analog input.

How does Core Audio set sample rate?

When I play a particular movie in QuickTime, the audio and video are out of sync. The movie plays fine on other computers.
This Mac Pro (OS 10.6.8) is used exclusively for Pro Tools and Final Cut Pro. The audio hardware is a Pro Tools HD Native card:
Native card --> Pro Tools Digital I/O boxes --> Lavry D/A converters --> monitors
The sample rate of the Digital I/O boxes is set by an external master clock, a Lavry Gold A/D converter.
I opened the DigiDesign Core Audio Manager and it says:
Connected @ 44.1K, 32 In/32 Out, Buffer Size 512
Yet the movie is at 48K (I know because I created it in Final Cut Pro), and the external clock is set at 48K. So, I don't know where the 41K in the Digidesign Core Audio Manager came from. This is why I am guessing the problem is sample rate.
Please help me understand what sets the sample rate.
Does the application using Core Audio set it?
If so, how is this made consistent with the sample rate set for the hardware by the external master clock?
Do I have to be sure I always change the external clock setting to be consistent with the movie being played?
BTW, I have not had a sync problem when I play video in Final Cut Pro..........it is always in sync. So, I have never worried about how Core Audio works. The sync problem is only with QuickTime.

Well, here is more information:
- I reinstalled QuickTime 7 and did many other things (trashed preferences,etc)
- I set the audio hardware (Pro Tools/HD Native card) to 48k
- I checked the Digi CoreAudio Manager and it said "Connected at 44.1K", even though the hardware was set to 48K
- I played the problem videos, and all are now in sync
- I check the Digi CoreAudio Manager and it still says 44.1K
- I checked the hardware and it is now set to 44.1K
I know that the videos are 48K, because I created them in Final Cut Pro X.
Does this mean that QuickTime 7 always converts videos to 44.1K, regardless of their sample rate?

How do I control the sampling rate of a PCI-6602 counter

Labview version: 7.1
Processor: Pentium 4 1.8 GHz
Hello All,
I have two avalanche photo diodes connected to two counter entrances on a 6602 (ctr 0 and ctr 1).
As can be seen in the attached VI, I'm generating a signal on ctr2 and using that as an external clock for the counters.
My objective is to accurately read the counter values at a rate of ~100KHz (i.e. 0.01 ms between measurements) and to be able to control the rate via the front panel. This should be possible (80MHz timebase), however when I run the program it is only able to actually sample at ~5 ms intervals. Also I'm encountering error 200141 even though I set the rate in the counter to 1M, which should buffer enough.
What am I doing wrong? Any help would be greatly appreciated.
Thanks a lot,
Attachments:
FRET_ver_14.vi ‏456 KB

Hello Aadam,
After looking at your code, I would not use the DAQ assistants to implement this. The DAQ assistant are best to be used for simple acquistion and since you are looking to use more lower level properties of you card, I would suggest to move to use the lower level VIs. It will be easier to understand where the problem is occurring at and will run better than using the DAQ assistant.
I have done some initial research for you to implement this design. I have described each of them below and how they will assist you.
The first example I have found is the Change Counter Output Frequency While the Task is Running. In this example, it will show you how to change the frequency and duty cycle of a counter output frequency task. One thing to remember about these counters are that the frequency will not change until the period has finished. For example, if you changed the frequency in the middle of a period of frequency of 1 Hz, it has to complete the 1Hz period before changing it to the next frequency.
The next example I would investgate is in the NI Example Finder called Correlated Dig Write With Counter.vi. The NI Example Finder can be found in Help » Find Examples... This VI will explain how to use the counter as a clock for another task. You will need to combine the concepts of the first example with this to make sure that you can vary the sample clock.
Finally, in the NI Example Finder, there is an example how to count digital events with an external clock called Count Digital Events-Buffered-Continuous-Ext Clk.vi. With this example, I first suggest to add the counter task and make sure you can get the external clock to work. After this, I would then implement changing clock.
Jim St
National Instruments
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How do i ensure my sampling rate is a constant and correct (@250Hz) when using AI Sample Channel vi

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Hi,
I have USB capture device which supports HDMI input and I wish to use it to connect to my digicam and stream it out with FMLE. While I can see that the video input is working properly, the audio is not working. The error message "Problem with audio capture device - Please verify that the audio device is working correctly and is not already in use." always appear when I try to select the device's audio device. Using the graphedit, I can see that the capture device's audio output pin only supports stereo 16-bit 48 kHz PCM output. As such, can I confirm that that FMLE only support 44.1kHz (as well as other 44.1kHz divisible) sampling rate?
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How to render audio with sample rate 48000hz using jmf

hi,
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hi,
In my application i need to play the audio with jmf player with sampling rate 48000hz. but i found that jmf player plays the audio with sampling rate of 44100hz only.but my application needs to play the audio with sampling rate of 48000hz .please help me how to do this using jmf .
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Hi,
I Just captured a small clip from my DV camera on final express 4. At the end of the capture i got a message saying that the sample rate on my source may be different to the rate on my capture and it may cause the video and audio to go out of sync. This did happen so i checked the camcorder and it is set to 12bit. How do i set the captute settings to suit??
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Can I ask a stupid question?
What do you mean "if you overrun" I just encountered all the above issues. First tape imported perfectly once I changed it to 32. The next one appeared to but then like jerryws1431 said, FCE quit. I wasn't here at the point it quit, but if was either after or during the "Validating Audio". Last time I looked it was validating.
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When feeding my macbookpro a digital audio signal via optical cable while viewing the audio midi setup utility, it shows that the mbp's internal clock automatically switches to the incoming sample rate. I got it to work with 441,48 and 96k. When I fead it the 882 sample rate it automatically switches back to the mbp's internal clock and reverts to line input instead of digital. So the audio midi setup utility shows when it is in digital input mode the three sample rates 441,48 and 96k in the format pop up window and not 882 so it must be just a software issue and I am wondering if there is a way to add the sample rate to the list. If it can take in 96k it should also be ale to take in 882. So does anyone know how you could ad a sample rate of 882 to the list in the audio midi utility format list?

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How to force digital input sample rate?

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