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  • grinch's Avatar
    06-13-2020, 03:18 AM
    Mostly posting here out of a sense of completion. Further topics of interest would be higher resolution interrupts for clean buffer transfer at 44.1kHz sample rate and a fix for the apparent bug in the USB audio...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-13-2020, 03:15 AM
    Got the parts in today to try the built-in SPDIF method. It's working great. I'm getting very clean signal with no dropouts. Additionally by running the SPDIF output at 48kHz I eliminate an buffer overruns in my output...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-06-2020, 10:09 PM
    After doing some more research I have another thought. Seems like this would be a great application for the new S/PDIF input object that was added to the audio library for the Teensy 4.0. I know some suggested an SPDIF...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-06-2020, 03:02 AM
    Here is the code I'm using to test: #include <Audio.h> AudioInputUSB usb1; AudioOutputMQS mqs; //just to trigger audio library update AudioConnection ...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-05-2020, 11:56 PM
    Tested this on another computer with built-in USB ports running OSX 10.12. I get the same overrun / underrun problem as before. One thing that would be helpful to know: is this a longstanding issue with the USB...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-03-2020, 12:08 AM
    I case it matters, I also have to use one of those stupid USB C to regular USB converter dongles since Apple decided to start eliminating ports. I've tried a couple of these out to see if it makes a difference and I get...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-03-2020, 12:05 AM
    1. Gotcha, I'll go with other options in that case. 2. That's fine, appreciate you just giving advice. The sample offset tracking thing is very case specific so I wasn't expecting to have anyone else do that for me....
    18 replies | 417 view(s)
  • grinch's Avatar
    06-02-2020, 11:29 PM
    Thank you for hopping on the thread Paul, was hoping I could get your input on this ;). That helps clear up a lot of my understanding. After making a test patch to check the overrun and underrun count variables it...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-02-2020, 08:10 PM
    Also hoping someone can tell me the function of "usb_high_speed" and how that variable gets set
    18 replies | 417 view(s)
  • grinch's Avatar
    06-02-2020, 08:09 PM
    I'm hoping someone can answer my original question. The behavior I'm getting seems to suggest that USB audio is discarding samples at some point, which seems weird. I'm wondering how this happens and why it's set up...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-02-2020, 08:04 PM
    -Max/MSP is a visual programming environment that's well set up for audio synthesis. The point here isn't to use Max though, but rather to get audio from any programming environment on a laptop. This could be Chuck,...
    18 replies | 417 view(s)
  • grinch's Avatar
    06-01-2020, 10:49 PM
    Bump.........
    18 replies | 417 view(s)
  • grinch's Avatar
    05-30-2020, 04:53 AM
    So I tried this with the Teensy 4.0, which seems to solve whatever dropout issue I was having with the Teensy 3.6. I am getting the occasional buffer overrun flag, which seems to be related to the limited resolution of...
    11 replies | 268 view(s)
  • grinch's Avatar
    05-30-2020, 04:45 AM
    I tried this using the AudioSynthWaveformDC object to generate a constant value for dropout detection output. As I would expect, this version detects no dropouts whatsoever. Left it running over an hour to test this....
    11 replies | 268 view(s)
  • grinch's Avatar
    05-30-2020, 03:45 AM
    Hi, I am working on an audio project using the Teensy 4.0 as a USB audio device. In this project I use a usb audio stream from Max/MSP to control a large array of binary shift register outputs, 64 in total. I have this...
    18 replies | 417 view(s)
  • grinch's Avatar
    05-28-2020, 02:12 AM
    Yeah I was already thinking of trying this. Got a couple Teensy 4.0s in the mail, and I'm going to see if it works any better once I switch them out. I've been looking on github for the Teensy4 core equivalent of...
    11 replies | 268 view(s)
  • grinch's Avatar
    05-27-2020, 04:36 AM
    This is the case. I set my interval timer priority to 0 in order to ensure it is completely sample accurate. I'm not exactly sure how this interacts with other timer priority stuff, but it is the highest priority that...
    11 replies | 268 view(s)
  • grinch's Avatar
    05-26-2020, 09:31 PM
    Hey all, this is mostly working well, but I'm experiencing an issue with dropped audio frames. Would be incredibly helpful if y'all were able to advise. Made a post about it here: POST
    13 replies | 395 view(s)
  • grinch's Avatar
    05-26-2020, 09:28 PM
    I'm really hoping Paul or someone else with in depth knowledge of the audio library can weigh in on this. My code is doing a multithreaded thing with two layers of interrupts, and I'm thinking that the dropouts may be a...
    11 replies | 268 view(s)
  • grinch's Avatar
    05-26-2020, 09:25 PM
    Hmmm... tired that out, doesn't seem to have much effect. When I compiled as debug there was a lag before dropouts started occurring but then they come back at the same rate as before. Was worth a shot though.
    11 replies | 268 view(s)
  • grinch's Avatar
    05-26-2020, 04:24 AM
    Here is the Max Patch I am using to test this. It sends a constant value of 8.0 / 32767.0 out of the left audio channel, which gets read as 0B00001000 in binary on the Teensy end, which corresponds to the 4th pin of my...
    11 replies | 268 view(s)
  • grinch's Avatar
    05-26-2020, 04:06 AM
    Hi, I am working on a Teensy 3.6 audio project where I am controlling an array of shift register outputs via a USB audio stream from Max/MSP. I've written a custom object to transfer the data from audio frames to the...
    11 replies | 268 view(s)
  • grinch's Avatar
    05-23-2020, 10:12 PM
    Actually working quite well now. The digitalWriteFast() function helped a ton. Removed a bunch of wobble from the waveform. I'm also calling the latch write first thing in my output function, so that it calls...
    13 replies | 395 view(s)
  • grinch's Avatar
    05-23-2020, 07:09 AM
    So I actually got a dirty proof of concept version of this working using a circular ring buffer and the IntervalTimer object. I've got a custom output object written that copies incoming audio blocks to an array, which...
    13 replies | 395 view(s)
  • grinch's Avatar
    05-23-2020, 12:00 AM
    I don't think DMA will work for my specific application. While there may theoretically be a way to hook up DMA transfers to a SPI buffer, in this case I need to transfer 64 bits at a time, and not have the chip select...
    13 replies | 395 view(s)
  • grinch's Avatar
    05-22-2020, 04:39 AM
    Do all the audio output objects rely on the DMA object interrupt? What would you recommend using as a timing source for an output that doesn't use DMA?
    13 replies | 395 view(s)
  • grinch's Avatar
    05-21-2020, 10:40 PM
    Hi, I am working on a project for which I'd like to write a custom output object for the Teensy audio library (using Teensy 3.6). To this end I have been studying the existing output objects in the Audio Library github....
    13 replies | 395 view(s)
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