#AUDIO LOOPBACK LATENCY TEST FULL#
#AUDIO LOOPBACK LATENCY TEST CODE#
#AUDIO LOOPBACK LATENCY TEST PC#

It was painful for me to hear, but the vast majority of people didn't even notice even after I pointed it out. I have created audio systems where there was a variable 5-8% pitch shift (for delay compensation reasons in really bad cases). I would also caution you about being too stringent in your audio specifications.

#AUDIO LOOPBACK LATENCY TEST FULL#

Nobody actually tries to delay things (unless you have on-board processing and ask them to), but you have to have a full sample in order to transmit/receive on the digital bus.ДЄs for vector instructions, even if you only had 1 current time sample to work with, you've got lots of DSP algorithms which work with quite a few past time samples so SIMD vector instructions would still be a win. The codecs are probably close to 1 sample of latency on DAC and ADC if you turn off on-board DSP processing. If you run that up to 192KHz, you get 80 samples. Let's assume 4 inches which means roughly 400us (I'm being VERY loose to make the math easy).ДЄt 48KHz, samples are roughly every 20us-so you get 20 samples (400us/20us) to stay within your latency budget. Or the crossover might be high or gradual enough that it does matter.)ДЄnyway, I'm looking for enough general information that I can evaluate it when the time comes.

#AUDIO LOOPBACK LATENCY TEST CODE#

(If the crossover frequency ends up being low enough and steep enough (overall latency is a small fraction of a single wave), this may all be a moot point I'm not going to hear the original anyway, where it matters, so just throw some pre-fab code at it and call it good. I have no idea what that acoustic lowpass is going to be, so I'm looking for enough general information that I can evaluate it when the time comes. Of course, all of this might not even matter, depending on the acoustic lowpass that I end up with, for which this DSP needs to be a complimentary highpass with transducer-correction and peak-limiting. What parameter(s) should I be looking for in a good datasheet? And are there any rules of thumb / tribal knowledge that would be useful as well, in terms of realtime DSP where the output might combine with the original input, after a small speed-of-the-wave delay of the original input? (1's of samples at 48kHz)

#AUDIO LOOPBACK LATENCY TEST PC#

For their intended application of PC audio, I can understand that it's not important, but for this project, it kinda is. I've looked at a few datasheets and, at least for the cheap ones, I can't find a parameter that tells me the overall latency. I expect a minimum of 2 samples, just because of how I2S works - latch and shift out from the ADC, then shift into the DAC and latch again - but I imagine that the conversions themselves aren't instantaneous either. Simulate this circuit вЂ“ Schematic created using CircuitLab So, to get a feel for what I'm stuck with, and how much I need to optimize and overpower my DSP code to fit in the time remaining (small buffers, even down to a single sample just to get it out NOW!, which means I can't use SIMD instructions - increased sample rate, not for 'audiophool' quality but just to shorten the turn-around time - etc.), what latency can I expect for a typical audio CODEC chip in this test circuit?: That's fine for a concert, where you can easily have more physical offset than that (~1 foot) between the mics and speakers, but for my project, I'm looking at several inches at most. In other words, a stereo recorder hooked up to a Y-splitter at the ADC input for one recording channel, and the DAC output for the other recording channel, would measure about 1ms offset between them. I have some experience using digital live audio systems that claim about 1ms latency from the ADC's, all the way through the (quite involved) DSP, to the DAC's.

Not because I'm hard of hearing, but to account for an acoustic lowpass caused by a different part of the project.

Microphones feeding earbuds with some DSP in between, all in a physically small space. I'm thinking way ahead about a possible future project which will contain, among many other things, a 'DIY hearing aid' of sorts.

Audio loopback latency test