ref: 7e11361bcf62fdaf6b17aeb7032c01990a567d0f
dir: /midi-dobend/
midi: implement pitch wheel this is an aborted attempt to implement pitch bending (event 0xe0). this maintains a list of active notes, storing note number, amplitude and bent frequency; this greatly reduces cpu time spent in run(), also alleviating the issue of delays between writes to /dev/audio being too great... it blows chunks: - greatly complexifies midi note handling - pitch steps are discrete and too noticeable, actually worsening playback (blatant example: doom e2m2), but don't yet know where T % f >= f/2 is coming from or how to fix this → i don't yet know what i'm doing nor how to solve this correctly diff -r 9c4b9c67ff16 sys/src/games/midi.c --- a/sys/src/games/midi.c Thu Feb 16 20:11:20 2017 +0100 +++ b/sys/src/games/midi.c Wed Feb 22 01:34:39 2017 +0200 @@ -3,19 +3,29 @@ enum { SAMPLE = 44100 }; +typedef struct Note Note; +typedef struct Tracker Tracker; + +struct Note { + int nt; + Tracker *src; + int ch; + uchar a; + int f; + int ½f; + Note *n; +} nl[256], np; + struct Tracker { uchar *data; char ended; uvlong t; - uchar notes[16][128]; + double bend[16]; int cmd; } *tr; -typedef struct Tracker Tracker; - int fd, ofd, div, tempo = 500000, ntrack; uvlong T; -int freq[128]; void * emallocz(int size) @@ -108,32 +118,23 @@ } void -run(uvlong n) +run(uvlong dt) { - int samp, j, k, l, no[128]; + int samp, l; uchar *s; - int t, f; + int t; short u; - Tracker *x; - - samp = n - T; + Note *n; + + samp = dt - T; if(samp <= 0) return; - memset(no, 0, sizeof no); - for(x = tr; x < tr + ntrack; x++){ - if(x->ended) - continue; - for(j = 0; j < 16; j++) - for(k = 0; k < 128; k++) - no[k] += x->notes[j][k]; - } s = emallocz(samp * 4); for(l = 0; l < samp; l++){ t = 0; - for(k = 0; k < 128; k++){ - f = (T % freq[k]) >= freq[k]/2 ? 1 : 0; - t += f * no[k]; - } + for(n = np.n; n != &np; n = n->n) + if(T % n->f >= n->½f) + t += n->a; u = t*10; s[4 * l] = s[4 * l + 2] = u; s[4 * l + 1] = s[4 * l + 3] = u >> 8; @@ -144,11 +145,70 @@ } void +bend(Tracker *src, int ch, int b) +{ + int f; + double d; + Note *n; + + d = (b - 8192) / 4095.5; + d = pow(2, d / 12); + src->bend[ch] = d; + for(n = np.n; n != &np; n = n->n){ + if(n->src != src || n->ch != ch) + continue; + f = SAMPLE / (440 * d * pow(1.05946, n->nt - 69)); + n->f = f; + n->½f = f / 2; + } +} + +void +pop(Tracker *src, int ch, int nt) +{ + Note *n, *p; + + for(p = &np, n = np.n; n != &np; p = n, n = n->n) + if(n->src == src && n->ch == ch && n->nt == nt){ + p->n = n->n; + memset(n, 0, sizeof *n); + return; + } +} + +void +push(Tracker *src, int ch, int nt, int a) +{ + int f; + Note *n, *p; + + for(p = &np, n = np.n; n != &np; p = n, n = n->n) + if(n->src == src && n->ch == ch && n->nt == nt){ + n->a = a; + return; + } + for(n = nl; n < nl + nelem(nl); n++) + if(n->src == nil) + break; + if(n == nl + nelem(nl)) + return; + n->src = src; + n->ch = ch; + n->nt = nt; + n->a = a; + f = SAMPLE / (440 * src->bend[ch] * pow(1.05946, nt - 69)); + n->f = f; + n->½f = f / 2; + p->n = n; + n->n = &np; +} + +void readevent(Tracker *src) { uvlong l; int n,t; - + l = tconv(getvar(src)); run(src->t += l); t = get8(src); @@ -161,13 +221,12 @@ src->cmd = t; switch(t >> 4){ case 0x8: - n = get8(src); + pop(src, t & 15, get8(src)); get8(src); - src->notes[t & 15][n] = 0; break; case 0x9: n = get8(src); - src->notes[t & 15][n] = get8(src); + push(src, t & 15, n, get8(src)); break; case 0xB: get16(src); @@ -175,6 +234,11 @@ case 0xC: get8(src); break; + case 0xE: + n = get8(src) & 0x7f; + n = get8(src) << 7 & 0x3f80 | n; + bend(src, t & 15, n); + break; case 0xF: t = get8(src); n = get8(src); @@ -204,7 +268,7 @@ void main(int argc, char **argv) { - int i, size; + int i, j, size; uvlong t, mint; Tracker *x, *minx; @@ -228,9 +292,10 @@ size = get32(nil); tr[i].data = emallocz(size); read(fd, tr[i].data, size); + for(j = 0; j < 16; j++) + tr[i].bend[j] = 1.0; } - for(i = 0; i < 128; i++) - freq[i] = SAMPLE / (440 * pow(1.05946, i - 69)); + np.n = &np; for(;;){ minx = nil; mint = 0;