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synthio: allow increasing number of channels

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12 channels works well on metro m7
This commit is contained in:
Jeff Epler 2023-03-31 10:51:03 -05:00
parent e8711ee836
commit 02f8a45dfa
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GPG Key ID: D5BF15AB975AB4DE
5 changed files with 68 additions and 46 deletions
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1
ports/mimxrt10xx/mpconfigport.mk
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@ -18,6 +18,7 @@ CIRCUITPY_AUDIOIO = 0
CIRCUITPY_AUDIOMIXER = 1
CIRCUITPY_AUDIOMP3 = 1
CIRCUITPY_AUDIOPWMIO = 1
CIRCUITPY_SYNTHIO_MAX_CHANNELS = 12
CIRCUITPY_BUSDEVICE = 1
CIRCUITPY_COUNTIO = 0
CIRCUITPY_FREQUENCYIO = 0

4
py/circuitpy_mpconfig.mk
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@ -437,6 +437,10 @@ CFLAGS += -DCIRCUITPY_SUPERVISOR=$(CIRCUITPY_SUPERVISOR)
CIRCUITPY_SYNTHIO ?= $(CIRCUITPY_AUDIOCORE)
CFLAGS += -DCIRCUITPY_SYNTHIO=$(CIRCUITPY_SYNTHIO)
CIRCUITPY_SYNTHIO_MAX_CHANNELS ?= 2
CFLAGS += -DCIRCUITPY_SYNTHIO_MAX_CHANNELS=$(CIRCUITPY_SYNTHIO_MAX_CHANNELS)
CIRCUITPY_SYS ?= 1
CFLAGS += -DCIRCUITPY_SYS=$(CIRCUITPY_SYS)

2
shared-bindings/audiocore/RawSample.c
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@ -40,7 +40,7 @@
//| def __init__(
//| self, buffer: ReadableBuffer, *, channel_count: int = 1, sample_rate: int = 8000
//| ) -> None:
//| """Create a RawSample based on the given buffer of signed values. If channel_count is more than
//| """Create a RawSample based on the given buffer of values. If channel_count is more than
//| 1 then each channel's samples should alternate. In other words, for a two channel buffer, the
//| first sample will be for channel 1, the second sample will be for channel two, the third for
//| channel 1 and so on.

105
shared-module/synthio/MidiTrack.c
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@ -27,7 +27,6 @@
#include "py/runtime.h"
#include "shared-bindings/synthio/MidiTrack.h"
#define LOUDNESS 0x4000 // 0.5
#define BITS_PER_SAMPLE 16
#define BYTES_PER_SAMPLE (BITS_PER_SAMPLE / 8)
#define SILENCE 0x80
@ -47,36 +46,51 @@ STATIC uint8_t parse_note(const uint8_t *buffer, uint32_t len, uint32_t *pos) {
return note;
}
STATIC void terminate_span(synthio_miditrack_obj_t *self, uint16_t *dur, uint16_t *max_dur) {
STATIC void terminate_span(synthio_miditrack_obj_t *self, uint16_t *dur) {
if (*dur) {
self->track[self->total_spans - 1].dur = *dur;
if (*dur > *max_dur) {
*max_dur = *dur;
}
*dur = 0;
} else {
self->total_spans--;
}
}
STATIC void add_span(synthio_miditrack_obj_t *self, uint8_t note1, uint8_t note2) {
synthio_midi_span_t span = { 0, {note1, note2} };
STATIC void add_span(synthio_miditrack_obj_t *self, const synthio_midi_span_t *span) {
self->track = m_realloc(self->track,
(self->total_spans + 1) * sizeof(synthio_midi_span_t));
self->track[self->total_spans++] = span;
self->track[self->total_spans++] = *span;
}
STATIC int find_channel_with_note(const synthio_midi_span_t *span, uint8_t note) {
for (int i = 0; i < CIRCUITPY_SYNTHIO_MAX_CHANNELS; i++) {
if (span->note[i] == note) {
return i;
}
}
return -1;
}
STATIC void change_span_note(synthio_miditrack_obj_t *self, uint8_t old_note, uint8_t new_note, uint16_t *dur) {
synthio_midi_span_t span = self->track[self->total_spans - 1];
int channel = find_channel_with_note(&span, old_note);
if (channel != -1) {
terminate_span(self, dur);
span.note[channel] = new_note;
add_span(self, &span);
}
}
void common_hal_synthio_miditrack_construct(synthio_miditrack_obj_t *self,
const uint8_t *buffer, uint32_t len, uint32_t tempo, uint32_t sample_rate) {
synthio_midi_span_t initial = { 0, {SILENCE, SILENCE} };
synthio_midi_span_t initial = { 0, {[0 ... (CIRCUITPY_SYNTHIO_MAX_CHANNELS - 1)] = SILENCE} };
self->sample_rate = sample_rate;
self->track = m_malloc(sizeof(synthio_midi_span_t), false);
self->next_span = 0;
self->total_spans = 1;
*self->track = initial;
uint16_t dur = 0, max_dur = 0;
uint16_t dur = 0;
uint32_t pos = 0;
while (pos < len) {
uint8_t c;
@ -91,37 +105,19 @@ void common_hal_synthio_miditrack_construct(synthio_miditrack_obj_t *self,
raise_midi_stream_error(pos);
}
// dur is carried over here so that if a note on/off message doesn't actually produce a change, the
// underlying "span" is extended. Otherwise, it is zeroed out in the call to `terminate_span`.
dur += delta * sample_rate / tempo;
switch (buffer[pos++] >> 4) {
case 8: { // Note Off
uint8_t note = parse_note(buffer, len, &pos);
// Ignore if not a note which is playing
synthio_midi_span_t last_span = self->track[self->total_spans - 1];
if (last_span.note[0] == note || last_span.note[1] == note) {
terminate_span(self, &dur, &max_dur);
if (last_span.note[0] == note) {
add_span(self, last_span.note[1], SILENCE);
} else {
add_span(self, last_span.note[0], SILENCE);
}
}
change_span_note(self, note, SILENCE, &dur);
break;
}
case 9: { // Note On
uint8_t note = parse_note(buffer, len, &pos);
// Ignore if two notes are already playing
synthio_midi_span_t last_span = self->track[self->total_spans - 1];
if (last_span.note[1] == SILENCE) {
terminate_span(self, &dur, &max_dur);
if (last_span.note[0] == SILENCE) {
add_span(self, note, SILENCE);
} else {
add_span(self, last_span.note[0], note);
}
}
change_span_note(self, SILENCE, note, &dur);
break;
}
case 10:
@ -142,8 +138,12 @@ void common_hal_synthio_miditrack_construct(synthio_miditrack_obj_t *self,
raise_midi_stream_error(pos);
}
}
terminate_span(self, &dur, &max_dur);
terminate_span(self, &dur);
uint16_t max_dur = 0;
for (int i = 0; i < self->total_spans; i++) {
max_dur = MAX(self->track[i].dur, max_dur);
}
self->buffer_length = max_dur * BYTES_PER_SAMPLE;
self->buffer = m_malloc(self->buffer_length, false);
}
@ -177,6 +177,16 @@ void synthio_miditrack_reset_buffer(synthio_miditrack_obj_t *self,
STATIC const uint16_t notes[] = {8372, 8870, 9397, 9956, 10548, 11175, 11840,
12544, 13290, 14080, 14917, 15804}; // 9th octave
static int count_active_channels(synthio_midi_span_t *span) {
int result = 0;
for (int i = 0; i < CIRCUITPY_SYNTHIO_MAX_CHANNELS; i++) {
if (span->note[i] != SILENCE) {
result += 1;
}
}
return result;
}
audioio_get_buffer_result_t synthio_miditrack_get_buffer(synthio_miditrack_obj_t *self,
bool single_channel_output, uint8_t channel, uint8_t **buffer, uint32_t *buffer_length) {
@ -187,19 +197,26 @@ audioio_get_buffer_result_t synthio_miditrack_get_buffer(synthio_miditrack_obj_t
synthio_midi_span_t span = self->track[self->next_span++];
*buffer_length = span.dur * BYTES_PER_SAMPLE;
uint8_t octave1 = span.note[0] / 12; // 0..10
uint8_t octave2 = span.note[1] / 12; // 0..10
int32_t base_freq1 = notes[span.note[0] % 12];
int32_t base_freq2 = notes[span.note[1] % 12];
int32_t sample_rate = self->sample_rate;
memset(self->buffer, 0, *buffer_length);
for (uint16_t i = 0; i < span.dur; i++) {
int16_t semiperiod1 = span.note[0] == SILENCE ? 0 :
((base_freq1 * i * 2) / sample_rate) >> (10 - octave1);
int16_t semiperiod2 = span.note[1] == SILENCE ? semiperiod1 :
((base_freq2 * i * 2) / sample_rate) >> (10 - octave2);
self->buffer[i] = ((semiperiod1 % 2 + semiperiod2 % 2) - 1) * LOUDNESS;
int32_t sample_rate = self->sample_rate;
int active_channels = count_active_channels(&span);
if (active_channels) {
int16_t loudness = 0x3fff / (1 + active_channels);
for (int chan = 0; chan < CIRCUITPY_SYNTHIO_MAX_CHANNELS; chan++) {
uint8_t octave = span.note[chan] / 12;
uint16_t base_freq = notes[span.note[chan] % 12];
if (span.note[chan] == SILENCE) {
continue;
}
for (uint16_t i = 0; i < span.dur; i++) {
int16_t semiperiod =
((base_freq * i * 2) / sample_rate) >> (10 - octave);
self->buffer[i] += semiperiod % 2 ? loudness : -loudness;
}
}
}
*buffer = (uint8_t *)self->buffer;
return self->next_span >= self->total_spans ?

2
shared-module/synthio/MidiTrack.h
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@ -33,7 +33,7 @@
typedef struct {
uint16_t dur;
uint8_t note[2];
uint8_t note[CIRCUITPY_SYNTHIO_MAX_CHANNELS];
} synthio_midi_span_t;
typedef struct {