CircuitPython - a Python implementation for teaching coding with microcontrollers https://git.suspectdevices.com/suspect-devices/circuitpython/atom?h=6.1.x 2020-06-02T00:14:38+00:00 2020-06-02T00:14:38+00:00 Jeff Epler jepler@gmail.com 2020-06-02T00:10:35+00:00 urn:sha1:0722dafc2464b414e680fab700f3f84cd54879df There were two main problems - word_buffer was being filled as though with unsigned samples, but during mixing all samples are kept in signed mode - If the first buffer was stopped, the voices_active flag got set anyway, even though the output buffer wasn't initialized yet, so the samples were mixed with indeterminate data We also cover the case where no buffer was playing, and ensure the output buffer is filled. This now works much better. Tested on neotrellis m4 playing back 4 mp3 streams at a time in signed-16, 22050Hz 2020-01-20T20:08:56+00:00 Jeff Epler jepler@gmail.com 2020-01-20T20:06:39+00:00 urn:sha1:b4ddee2bb6ae40a73efe15e30de8d33ab9ce8011 2020-01-20T20:08:32+00:00 Jeff Epler jepler@gmail.com 2020-01-20T20:08:32+00:00 urn:sha1:982c63a71712fc9092b35fca3ef34e4b404c03cb 2020-01-16T16:48:38+00:00 Jeff Epler jepler@gmail.com 2020-01-12T17:02:47+00:00 urn:sha1:449dbea4567dbc27a01ae695b9cebf776a6927f0 This removes downscaling (halving-add) when multiple voices are being mixed. To avoid clipping, and get similar behavior to before, set the "level" of each voice to (1/voice_count). Slow paths that were applicable to only M0 chips were removed. As a side effect, the internal volume representation is now 0 .. 0x8000 (inclusive), which additionally makes a level of exactly 0.5 representable. Testing performed, on PyGamer: For all 4 data cases, for stereo and mono, for 1 and 2 voices, play pure sign waves represented as RawSamples and view the result on a scope and through headphones. Also, scope the amount of time spent in background tasks. Code size: growth of +272 bytes Performance (time in background task when mixing 2 stereo 16-bit voices): 76us per down from 135us (once per ~2.9ms long term average) (Decrease from 4.7% to 2.4% of all CPU time) 2020-01-16T16:31:26+00:00 Jeff Epler jepler@gmail.com 2020-01-12T16:12:42+00:00 urn:sha1:e6869c8983ba732f77076242c86041aa77a047e0 2019-12-04T15:31:52+00:00 Jeff Epler jepler@gmail.com 2019-12-04T15:31:52+00:00 urn:sha1:feb8eb935bd69ce855533bf9a4316e3025602c1a This eases addition of new sample sources, since the manual virtual function dispatch functions are just calls via a protocol 2019-09-09T02:18:15+00:00 jepler jepler@gmail.com 2019-09-09T02:17:36+00:00 urn:sha1:8768896d6b0ddb35568ad996781a33fd3a0df94f These arguments are constrained to be compile-time constants, a fact that gcc complains about under "-Og" optimization, but not in normal builds. Declare them as enumerated types 2019-09-04T03:25:27+00:00 sommersoft sommersoft@gmail.com 2019-09-04T03:25:27+00:00 urn:sha1:edfcee29ff88faa35a75a979cb74ad64553289a6 2019-09-01T22:36:29+00:00 sommersoft sommersoft@gmail.com 2019-09-01T22:36:29+00:00 urn:sha1:362c1664ae5979f288e8cb12d528f8cd44100410 2019-08-31T22:36:54+00:00 sommersoft sommersoft@gmail.com 2019-08-31T22:36:54+00:00 urn:sha1:3c7c3c98d7f497df33f0503162fb7b1721ef7ecd