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Thread: Best microSD card for reading?

  1. #1
    Junior Member
    Join Date
    Sep 2016
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    13

    Best microSD card for reading?

    Hi, I am trying to complete a small project where I use the Audio Shield as a sampler. i have loaded 60 RAW files onto a card, each 16-bit LSB first signed int samples, about a few seconds mono per note, one file per note, and I listen to note ins coming over serial and play them through a mixer. I am using this Sandisk 16GB card that is recommended by PJRC: https://www.pjrc.com/store/teensy3_audio.html

    Using that card, I can get 2 or 3 at most RAW files playing at once. Since I'd like more, I filed a pull request to be able to pass play_sd_raw an optional parameter to load in 22050 Hz samples instead of 44100 and simply upsample them on playback -- this should increase my polyphony by about 2x. With this patch in, my polyphony has gone up to 5 and maybe 6. At 6 or 7 the sound glitches and the board freezes for a few seconds (presumably while it slowly reads out the samples) but then comes back.

    You can see on the pull request link that others claim to have far more polyphony than I do. What cards are you using or are there any other tricks to increasing polyphony of playback from a microSD card? I am next investigating the flashRAM, but it's only 16MB and my sample set is 31MB at 22kHz.
    Last edited by bwhitman; 09-05-2016 at 11:10 AM.

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