Initial linear interpolating resampler. This resampler really needs to be ripped out of the codec, and put into the playback system. Optimising probably wouldn't hurt either, currently it slows down playback quite a bit.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@6809 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 84 insertions, 7 deletions

diff --git a/apps/plugins/codecmpa.c b/apps/plugins/codecmpa.c
index 67062bc40b..768c3fe0fd 100644
--- a/apps/plugins/codecmpa.c
+++ b/apps/plugins/codecmpa.c
@@ -169,6 +169,7 @@ unsigned char OutputBuffer[OUTPUT_BUFFER_SIZE];
 unsigned char *OutputPtr;
 unsigned char *GuardPtr=NULL;
 const unsigned char *OutputBufferEnd=OutputBuffer+OUTPUT_BUFFER_SIZE;
+long resampled_data[2][5000]; /* enough to cope with 11khz upsampling */
 
 mad_fixed_t mad_frame_overlap[2][32][18] IDATA_ATTR;
 unsigned char mad_main_data[MAD_BUFFER_MDLEN] IDATA_ATTR;
@@ -182,6 +183,79 @@ extern char iramend[];
 
 #undef DEBUG_GAPLESS
 
+struct resampler {
+    long last_sample, phase, delta;
+};
+
+#if CONFIG_CPU==MCF5249 && !defined(SIMULATOR)
+
+#define INIT() asm volatile ("move.l #0xb0, %macsr") /* frac, round, clip */
+#define FRACMUL(x, y) \
+({ \
+    long t; \
+    asm volatile ("mac.l %[a], %[b], %%acc0\n\t" \
+                  "movclr.l %%acc0, %[t]\n\t" \
+                  : [t] "=r" (t) : [a] "r" (x), [b] "r" (y)); \
+    t; \
+})
+
+#else
+
+#define INIT()
+#define FRACMUL(x, y) (long)(((long long)(x)*(long long)(y)) << 1)
+#endif
+
+/* linear resampling, introduces one sample delay, because of our inability to
+   look into the future at the end of a frame */
+long downsample(long *in, long *out, int num, struct resampler *s)
+{
+    long i = 1, pos;
+    long last = s->last_sample;
+
+    INIT();
+    pos = s->phase >> 16;
+    /* check if we need last sample of previous frame for interpolation */
+    if (pos > 0)
+        last = in[pos - 1];
+    out[0] = last + FRACMUL((s->phase & 0xffff) << 15, in[pos] - last);
+    s->phase += s->delta;
+    while ((pos = s->phase >> 16) < num) {
+        out[i++] = in[pos - 1] + FRACMUL((s->phase & 0xffff) << 15, in[pos] - in[pos - 1]);
+        s->phase += s->delta;
+    }
+    /* wrap phase accumulator back to start of next frame */
+    s->phase -= num << 16;
+    s->last_sample = in[num - 1];
+    return i;
+}
+
+long upsample(long *in, long *out, int num, struct resampler *s)
+{
+    long i = 0, pos;
+
+    INIT();
+    while ((pos = s->phase >> 16) == 0) {
+        out[i++] = s->last_sample + FRACMUL((s->phase & 0xffff) << 15, in[pos] - s->last_sample);
+        s->phase += s->delta;
+    }
+    while ((pos = s->phase >> 16) < num) {
+        out[i++] = in[pos - 1] + FRACMUL((s->phase & 0xffff) << 15, in[pos] - in[pos - 1]);
+        s->phase += s->delta;
+    }
+    /* wrap phase accumulator back to start of next frame */
+    s->phase -= num << 16;
+    s->last_sample = in[num - 1];
+    return i;
+}
+
+long resample(long *in, long *out, int num, struct resampler *s)
+{
+    if (s->delta >= (1 << 16))
+        return downsample(in, out, num, s);
+    else
+        return upsample(in, out, num, s);
+}
+
 /* this is the plugin entry point */
 enum plugin_status plugin_start(struct plugin_api* api, void* parm)
 {
@@ -202,7 +276,8 @@ enum plugin_status plugin_start(struct plugin_api* api, void* parm)
   int i;
   int yieldcounter = 0;
   int stop_skip, start_skip;
-  
+  struct resampler lr = { 0, 0, 0 }, rr = { 0, 0, 0 };
+  long length;  
   /* Generic plugin inititialisation */
 
   TEST_PLUGIN_API(api);
@@ -213,7 +288,7 @@ enum plugin_status plugin_start(struct plugin_api* api, void* parm)
 #endif
 
   /* This function sets up the buffers and reads the file into RAM */
-
+  
   if (codec_init(api, ci)) {
     return PLUGIN_ERROR;
   }
@@ -258,7 +333,6 @@ enum plugin_status plugin_start(struct plugin_api* api, void* parm)
   while (!*ci->taginfo_ready)
     rb->yield();
   
-  
   ci->request_buffer(&size, ci->id3->first_frame_offset);
   ci->advance_buffer(size);
  
@@ -290,7 +364,7 @@ enum plugin_status plugin_start(struct plugin_api* api, void* parm)
   rb->splash(HZ*5, true, buf2);
   rb->snprintf(buf2, sizeof(buf2), "frequency: %d", ci->id3->frequency);
   rb->splash(HZ*5, true, buf2); */
-  
+  lr.delta = rr.delta = ci->id3->frequency*65536/44100; 
   /* This is the decoding loop. */
   while (1) {
     rb->yield();
@@ -375,7 +449,10 @@ enum plugin_status plugin_start(struct plugin_api* api, void* parm)
     /* We skip start_skip number of samples here, this should only happen for
        very first frame in the stream. */
     /* TODO: possible for start_skip to exceed one frames worth of samples? */
-    for (i = start_skip;i<Synth.pcm.length;i++)
+    length = resample((long *)&Synth.pcm.samples[0][start_skip], resampled_data[0], Synth.pcm.length, &lr);
+    if (MAD_NCHANNELS(&Frame.header) == 2)
+        resample((long *)&Synth.pcm.samples[1][start_skip], resampled_data[1], Synth.pcm.length, &rr);
+    for (i = 0;i<length;i++)
     {
       start_skip = 0; /* not very elegant, and might want to keep this value */
       samplesdone++;
@@ -390,7 +467,7 @@ enum plugin_status plugin_start(struct plugin_api* api, void* parm)
       }*/
       
       /* Left channel */
-      Sample=scale(Synth.pcm.samples[0][i],&d0);
+      Sample=scale(resampled_data[0][i],&d0);
       *(OutputPtr++)=Sample>>8;
       *(OutputPtr++)=Sample&0xff;
 
@@ -398,7 +475,7 @@ enum plugin_status plugin_start(struct plugin_api* api, void* parm)
        * the right output channel is the same as the left one.
        */
       if(MAD_NCHANNELS(&Frame.header)==2)
-        Sample=scale(Synth.pcm.samples[1][i],&d1);
+        Sample=scale(resampled_data[1][i],&d1);
       *(OutputPtr++)=Sample>>8;
       *(OutputPtr++)=Sample&0xff;