ref: 1a450db960aa3c542c84a5fff0f66c5ce95c853f
parent: 9d60d8262e4ab285da2903192a341ceb81a05eb5
author: cinap_lenrek <[email protected]>
date: Sun Feb 5 22:34:21 EST 2012
oggdec: resample to target frequency
--- a/sys/src/cmd/audio/oggdec/oggdec.c
+++ b/sys/src/cmd/audio/oggdec/oggdec.c
@@ -26,12 +26,83 @@
#include <math.h>
#include <vorbis/codec.h>
+int rate = 44100;
-ogg_int16_t convbuffer[4096]; /* take 8k out of the data segment, not the stack */
-int convsize=4096;
+enum {+ Max = 32767,
+ Min = -32768,
+};
-extern void _VDBG_dump(void);
+typedef unsigned long ulong;
+typedef unsigned char uchar;
+typedef struct Chan Chan;
+struct Chan
+{+ unsigned long phase;
+ float last;
+};
+
+static uchar*
+resample(Chan *c, float *src, uchar *dst, int mono, ulong delta, ulong count)
+{+ float f, last, val;
+ ulong phase, pos;
+ int out;
+
+ last = c->last;
+ phase = c->phase;
+ pos = phase >> 16;
+ while(pos < count){+ val = src[pos];
+ if(pos)
+ last = src[pos-1];
+ f = (float)(phase&0xFFFF)/0x10000;
+ out = (last + (val - last) * f) * 32767.f;
+ /* cliping */
+ if(out > Max)
+ out = Max;
+ else if(out < Min)
+ out = Min;
+ *dst++ = out;
+ *dst++ = out >> 8;
+ if(mono){+ *dst++ = out;
+ *dst++ = out >> 8;
+ } else
+ dst += 2;
+ phase += delta;
+ pos = phase >> 16;
+ }
+ c->last = val;
+ if(delta < 0x10000)
+ c->phase = phase & 0xFFFF;
+ else
+ c->phase = phase - (count << 16);
+ return dst;
+}
+
+static void
+output(float **pcm, int samples, vorbis_info *vi)
+{+ static uchar *buf;
+ static int nbuf;
+ static Chan c1, c0;
+ ulong n, delta;
+ uchar *p;
+
+ delta = ((ulong)vi->rate << 16) / rate;
+ n = 4 * ((ulong)vi->rate + samples * rate) / (ulong)vi->rate;
+ if(n > nbuf){+ nbuf = n;
+ buf = realloc(buf, nbuf);
+ }
+ if(vi->channels == 2)
+ resample(&c1, pcm[1], buf+2, 0, delta, samples);
+ p = resample(&c0, pcm[0], buf, vi->channels == 1, delta, samples);
+ fwrite(buf, p-buf, 1, stdout);
+}
+
int main(){ogg_sync_state oy; /* sync and verify incoming physical bitstream */
ogg_stream_state os; /* take physical pages, weld into a logical
@@ -167,8 +238,6 @@
fprintf(stderr,"Encoded by: %s\n\n",vc.vendor);
}
- convsize=4096/vi.channels;
-
/* OK, got and parsed all three headers. Initialize the Vorbis
packet->PCM decoder. */
vorbis_synthesis_init(&vd,&vi); /* central decode state */
@@ -196,56 +265,13 @@
if(result<0){ /* missing or corrupt data at this page position *//* no reason to complain; already complained above */
}else{- /* we have a packet. Decode it */
float **pcm;
int samples;
-
if(vorbis_synthesis(&vb,&op)==0) /* test for success! */
vorbis_synthesis_blockin(&vd,&vb);
- /*
-
- **pcm is a multichannel float vector. In stereo, for
- example, pcm[0] is left, and pcm[1] is right. samples is
- the size of each channel. Convert the float values
- (-1.<=range<=1.) to whatever PCM format and write it out */
-
while((samples=vorbis_synthesis_pcmout(&vd,&pcm))>0){- int j;
- int clipflag=0;
- int bout=(samples<convsize?samples:convsize);
-
- /* convert floats to 16 bit signed ints (host order) and
- interleave */
- for(i=0;i<vi.channels;i++){- ogg_int16_t *ptr=convbuffer+i;
- float *mono=pcm[i];
- for(j=0;j<bout;j++){-#if 1
- int val=mono[j]*32767.f;
-#else /* optional dither */
- int val=mono[j]*32767.f+drand48()-0.5f;
-#endif
- /* might as well guard against clipping */
- if(val>32767){- val=32767;
- clipflag=1;
- }
- if(val<-32768){- val=-32768;
- clipflag=1;
- }
- *ptr=val;
- ptr+=vi.channels;
- }
- }
-
- if(clipflag)
- fprintf(stderr,"Clipping in frame %ld\n",(long)(vd.sequence));
-
-
- fwrite(convbuffer,2*vi.channels,bout,stdout);
-
- vorbis_synthesis_read(&vd,bout); /* tell libvorbis how
+ output(pcm, samples, &vi);
+ vorbis_synthesis_read(&vd,samples); /* tell libvorbis how
many samples we
actually consumed */
}