djsundog/circuitpython
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

synthio: Fix FIR filtering when audio is stereo

Browse Source
This commit is contained in:
Jeff Epler 2023-05-12 13:44:49 -05:00
parent 03abc623ef
commit f68ab9c5c2
No known key found for this signature in database
GPG Key ID: D5BF15AB975AB4DE
1 changed files with 6 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
shared-module/synthio/__init__.c
View File

@ -314,19 +314,21 @@ STATIC void run_fir(synthio_synth_t *synth, int32_t *out_buffer32, uint16_t dur)
size_t fir_len = synth->filter_bufinfo.len / sizeof(int16_t);
int32_t *in_buf = synth->filter_buffer;
int synth_chan = synth->channel_count;
// FIR and copy values to output buffer
for (int16_t i = 0; i < dur; i++) {
for (int16_t i = 0; i < dur * synth_chan; i++) {
int32_t acc = 0;
for (size_t j = 0; j < fir_len; j++) {
// shift 5 here is good for up to 32 filtered voices, else might wrap
acc = acc + (in_buf[j] * (coeff[j] >> 5));
acc = acc + (in_buf[j * synth_chan] * (coeff[j] >> 5));
}
*out_buffer32++ = acc >> 10;
in_buf++;
}
// Move values down so that they get filtered next time
memmove(synth->filter_buffer, &synth->filter_buffer[dur], fir_len * sizeof(int32_t));
memmove(synth->filter_buffer, &synth->filter_buffer[dur * synth_chan], fir_len * sizeof(int32_t) * synth_chan);
}
STATIC bool synthio_synth_get_note_filtered(mp_obj_t note_obj) {
@ -359,7 +361,7 @@ void synthio_synth_synthesize(synthio_synth_t *synth, uint8_t **bufptr, uint32_t
if (synth->filter_buffer) {
int32_t *filter_start = &synth->filter_buffer[synth->filter_bufinfo.len * synth->channel_count / sizeof(int16_t)];
memset(filter_start, 0, dur * sizeof(int32_t));
memset(filter_start, 0, dur * synth->channel_count * sizeof(int32_t));
for (int chan = 0; chan < CIRCUITPY_SYNTHIO_MAX_CHANNELS; chan++) {
mp_obj_t note_obj = synth->span.note_obj[chan];