SD Audio playback speed

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Just from a marketing standpoint I think this feature would be a selling point compared to all the other "effects" the teensy and audio library has to offer.

People don't pay for this software, they buy Teensy boards. So my time is split between making hardware and writing software. For the last 2 years, nearly all my engineering time had gone into making Teensy 4.0.

I am hopeful to spend time again on the audio library features (not just supporting new hardware) again this summer. But the reality is projects like this always compete for engineering time with tons of other stuff. There's never enough time to implement everything.
 
This is exactly what I'm missing in all audio libs and boards, the option to chance the speed of a playing sample, even backwards.

Just tried this fork on a Teensy3.6 and it works but stops when playing in reverse and the pointer reaches zero the board freezes. @moo had the same issues.
Is there someone who got a solution?
 
Subsequently I’ve tested it between -4.0 and 4.0... works successfully. beyond that I’ve not tested.
Hi @Moo, Thanks a lot for this, I adapted you ResamplingSdReader for playFlashRaw, and now I would like to make a version for the playMemory, but the core code of that object it's pretty different to the playSdRaw,
do you have any suggestion about where to start?
thanks in advance
 
ResamplingSdReader is a substitution class which replaces the Sd file reading part of the SD raw player. It has the simple function of returning altered audio buffer. in the simple case, lets say at 0.5 rate, it should return 2 samples for every one read. at 2.0 rate, it should return every second sample. I simply use a float variable to keep track of the progress, and advance the read sample if the float >= 1.0.

By the way, I have a more recent version of the ResamplingSdReader here, the issue where the device would freeze when playing backward past the begging was fixed. https://github.com/newdigate/teensy-variable-playback

I have been meaning to make flash and array compatible but just not had time yet :)
 
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