Hello,
I'm trying to figure out if I would be able to build a certain piece of audio hardware I'm imagining using the Teensy. I really enjoyed Paul's demo video of the multi-tap delay. I have a design in mind for a multi-channel delay unit. I've also been looking for an excuse to start playing with the Teensy Audio library.
However, my concept involves being able to switch between & merge multiple channels of delayed audio -- at least four, to be really useful. And I imagine the sample length being something like ten seconds per channel. If I round up my total audio buffer size to sixty seconds, then my audio buffer would need to be 60 * 48khz * 16 bit samples = 5.76 megabytes.
Certainly that would fit on an SD card, and I could stick that in the teensy audio board's SD slot. But I've read there's limits to how fast SD cards can be read, and that getting even two simultaneous channels to play back at once (at audio bandwidth) requires a particular breed of SD card. (Could there be an SD card somewhere that's optimized for random access?)
I read about attaching a RAM chip that gets the memory buffer up to 1.5 seconds, but that's still almost two orders of magnitude too small.
I also read how 128 megabits of additional flash can be added to the teensy, equivalent (i hope) to 16 megabytes. But I'd be constantly re-writing this memory. It seems like flash could be a bad choice there. Although 100,000 write/erase cycles might take me a long time to use up ... I guess it would work for a while, if that spec can be believed. (If that flash chip can be socketed for easy replacement, I'd be less wary.)
On the other hand, I do have a pile of old laptop RAM in my basement, and I've read that the Cortex M4 has an auxilliary memory controller that can read SDRAM. Is there a way to hook up an old DIMM or SIMM to the Teensy 3.2 and use that as a buffer?
Thanks for any advice,
-mykle-
I'm trying to figure out if I would be able to build a certain piece of audio hardware I'm imagining using the Teensy. I really enjoyed Paul's demo video of the multi-tap delay. I have a design in mind for a multi-channel delay unit. I've also been looking for an excuse to start playing with the Teensy Audio library.
However, my concept involves being able to switch between & merge multiple channels of delayed audio -- at least four, to be really useful. And I imagine the sample length being something like ten seconds per channel. If I round up my total audio buffer size to sixty seconds, then my audio buffer would need to be 60 * 48khz * 16 bit samples = 5.76 megabytes.
Certainly that would fit on an SD card, and I could stick that in the teensy audio board's SD slot. But I've read there's limits to how fast SD cards can be read, and that getting even two simultaneous channels to play back at once (at audio bandwidth) requires a particular breed of SD card. (Could there be an SD card somewhere that's optimized for random access?)
I read about attaching a RAM chip that gets the memory buffer up to 1.5 seconds, but that's still almost two orders of magnitude too small.
I also read how 128 megabits of additional flash can be added to the teensy, equivalent (i hope) to 16 megabytes. But I'd be constantly re-writing this memory. It seems like flash could be a bad choice there. Although 100,000 write/erase cycles might take me a long time to use up ... I guess it would work for a while, if that spec can be believed. (If that flash chip can be socketed for easy replacement, I'd be less wary.)
On the other hand, I do have a pile of old laptop RAM in my basement, and I've read that the Cortex M4 has an auxilliary memory controller that can read SDRAM. Is there a way to hook up an old DIMM or SIMM to the Teensy 3.2 and use that as a buffer?
Thanks for any advice,
-mykle-
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