Changeset 1844 for pjproject/trunk/pjmedia/src/pjmedia/wsola.c

Timestamp:

Mar 4, 2008 3:37:45 PM (16 years ago)

Author:

bennylp

Message:

More ticket #438: improve docs, added channel_count in wsola, etc.

File:

• pjproject/trunk/pjmedia/src/pjmedia/wsola.c (modified) (11 diffs)

pjproject/trunk/pjmedia/src/pjmedia/wsola.c

@@ -37 +37 @@
 
 /* Generate extra samples, in msec */
-#define GEN_EXTRA_PTIME (0.0)
+#define GEN_EXTRA_PTIME (5)
 
 /* Number of frames in erase buffer */
@@ -54 +54 @@
 
 
+/* Buffer content:
+ *
+ *   t0   time    tn
+ *   ---------------->
+ *
+ * +---------+-------+-------+---          --+
+ * | history | frame | extra | ...empty...   |
+ * +---------+-------+-------+----        ---+
+ * ^         ^               ^               ^
+ * buf    hist_cnt        cur_cnt          buf_cnt
+ *           or
+ *       frm pointer
+ *
+ * History count (hist_cnt) is a constant value, initialized upon 
+ * creation.
+ *
+ * At any particular time, the buffer will contain at least 
+ * (hist_cnt+samples_per_frame) samples.
+ *
+ * A "save" operation will append the frame to the end of the 
+ * buffer, return the samples right after history (the frm pointer),
+ * and shift the buffer by one frame.
+ */
+
+/* WSOLA structure */
 struct pjmedia_wsola
 {
     unsigned    clock_rate;     /* Sampling rate.                       */
-    pj_uint16_t samples_per_frame;/* Samples per frame.                 */
+    pj_uint16_t samples_per_frame;/* Samples per frame (const)          */
+    pj_uint16_t channel_count;  /* Samples per frame (const)            */
     pj_uint16_t options;        /* Options.                             */
-    pj_uint16_t hist_cnt;       /* # of history samples.                */
-    pj_uint16_t buf_cnt;        /* Total buffer capacity                */
+    pj_uint16_t hist_cnt;       /* # of history samples (const)         */
+    pj_uint16_t buf_cnt;        /* Total buffer capacity (const)        */
     pj_uint16_t cur_cnt;        /* Cur # of samples, inc. history       */
-    pj_uint16_t template_size;  /* Template size.                       */
-    pj_uint16_t min_extra;      /* Min extra samples for merging.       */
-    pj_uint16_t gen_extra;      /* Generate extra samples.              */
+    pj_uint16_t template_size;  /* Template size (const)                */
+    pj_uint16_t min_extra;      /* Min extra samples for merging (const)*/
+    pj_uint16_t gen_extra;      /* Generate extra samples (const)       */
     pj_uint16_t expand_cnt;     /* Number of expansion currently done   */
 
@@ -124 +150 @@
     }
 
-    TRACE_((THIS_FILE, "found pitch at %u", best-beg));
+    /*TRACE_((THIS_FILE, "found pitch at %u", best-beg));*/
     return best;
 }
@@ -208 +234 @@
     }
 
-    TRACE_((THIS_FILE, "found pitch at %u", best-beg));
+    /*TRACE_((THIS_FILE, "found pitch at %u", best-beg));*/
     return best;
 }
@@ -293 +319 @@
                                           unsigned clock_rate,
                                           unsigned samples_per_frame,
+                                          unsigned channel_count,
                                           unsigned options,
                                           pjmedia_wsola **p_wsola)
@@ -302 +329 @@
     PJ_ASSERT_RETURN(clock_rate <= 65535, PJ_EINVAL);
     PJ_ASSERT_RETURN(samples_per_frame < clock_rate, PJ_EINVAL);
+    PJ_ASSERT_RETURN(channel_count > 0, PJ_EINVAL);
 
     wsola = PJ_POOL_ZALLOC_T(pool, pjmedia_wsola);
@@ -307 +335 @@
     wsola->clock_rate= (pj_uint16_t) clock_rate;
     wsola->samples_per_frame = (pj_uint16_t) samples_per_frame;
+    wsola->channel_count = (pj_uint16_t) channel_count;
     wsola->options   = (pj_uint16_t) options;
     wsola->hist_cnt  = (pj_uint16_t)(samples_per_frame * HISTSZ);
@@ -360 +389 @@
     PJ_UNUSED_ARG(options);
 
-    pjmedia_zero_samples(wsola->buf, wsola->cur_cnt);
     wsola->cur_cnt = (pj_uint16_t)(wsola->hist_cnt + 
                                    wsola->samples_per_frame);
+    pjmedia_zero_samples(wsola->buf, wsola->cur_cnt);
     return PJ_SUCCESS;
 }
@@ -374 +403 @@
 
     for (rep=1;; ++rep) {
-        short *start;
-        unsigned dist;
-
-        start = find_pitch(wsola->frm, wsola->buf, 
-                           wsola->frm - (wsola->samples_per_frame >> 1),
+        short *start, *frm;
+        unsigned min_dist, max_dist, dist;
+
+        frm = wsola->buf + wsola->cur_cnt - frmsz;
+        pj_assert(frm - wsola->buf >= wsola->hist_cnt);
+
+        max_dist = wsola->hist_cnt;
+        min_dist = frmsz >> 1;
+
+        start = find_pitch(frm, frm - max_dist, frm - min_dist,
                            wsola->template_size, 1);
 
+        /* Should we make sure that "start" is really aligned to
+         * channel #0, in case of stereo? Probably not necessary, as
+         * find_pitch() should have found the best match anyway.
+         */
+
         if (wsola->options & PJMEDIA_WSOLA_NO_HANNING) {
-            overlapp_add_simple(wsola->mergebuf, wsola->samples_per_frame,
-                                wsola->frm, start);
+            overlapp_add_simple(wsola->mergebuf, frmsz,frm, start);
         } else {
-            overlapp_add(wsola->mergebuf, wsola->samples_per_frame,
-                         wsola->frm, start, wsola->hanning);
-        }
-
-        dist = wsola->frm - start;
-        pjmedia_move_samples(wsola->frm + frmsz, start + frmsz, 
+            overlapp_add(wsola->mergebuf, frmsz, frm, start, wsola->hanning);
+        }
+
+        /* How many new samples do we have */
+        dist = frm - start;
+
+        /* Copy the "tail" (excess frame) to the end */
+        pjmedia_move_samples(frm + frmsz, start + frmsz, 
                              wsola->buf+wsola->cur_cnt - (start+frmsz));
 
-        pjmedia_copy_samples(wsola->frm, wsola->mergebuf, frmsz);
-
+        /* Copy the merged frame */
+        pjmedia_copy_samples(frm, wsola->mergebuf, frmsz);
+
+        /* We have new samples */
         wsola->cur_cnt = (pj_uint16_t)(wsola->cur_cnt + dist);
+
+        pj_assert(wsola->cur_cnt <= wsola->buf_cnt);
+
         generated += dist;
 
         if (generated >= needed) {
-            assert(wsola->cur_cnt <= wsola->buf_cnt);
             TRACE_((THIS_FILE, "WSOLA frame expanded after %d iterations", 
                     rep));
@@ -469 +513 @@
     if (prev_lost && extra >= wsola->min_extra) {
         short *dst = wsola->buf + wsola->hist_cnt + wsola->samples_per_frame;
-        unsigned i;
-
+
+        /* Smoothen the transition. This will also erase the excess
+         * samples
+         */
         overlapp_add_simple(dst, extra, dst, frm);
 
-        for (i=extra; i<wsola->samples_per_frame; ++i)
-            dst[i] = frm[i];
-
-        
+        /* Copy remaining samples from the frame */
+        pjmedia_copy_samples(dst+extra, frm+extra, 
+                             wsola->samples_per_frame-extra);
+
+        /* Retrieve frame */
         pjmedia_copy_samples(frm, wsola->frm, wsola->samples_per_frame);
+
+        /* Remove excess samples */
         wsola->cur_cnt = (pj_uint16_t)(wsola->hist_cnt + 
                                        wsola->samples_per_frame);
+
+        /* Shift buffer */
         pjmedia_move_samples(wsola->buf, wsola->buf+wsola->samples_per_frame,
                               wsola->cur_cnt);
@@ -490 +541 @@
         }
 
+        /* Append frame */
         pjmedia_copy_samples(wsola->buf + wsola->cur_cnt, frm, 
                              wsola->samples_per_frame);
+
+        /* Retrieve frame */
         pjmedia_copy_samples(frm, wsola->frm, 
                              wsola->samples_per_frame);
+
+        /* Shift buffer */
         pjmedia_move_samples(wsola->buf, wsola->buf+wsola->samples_per_frame,
                              wsola->cur_cnt);