More work on ticket #438: Workaround for frame bursts from audio devices. See the ticket for more information

git-svn-id: https://svn.pjsip.org/repos/pjproject/trunk@1715 74dad513-b988-da41-8d7b-12977e46ad98

pjmedia/include/pjmedia/config.h

@@ -97,23 +97,15 @@
  * The delay buffer also performs the best delay calculation
  * for the sound device, and will try to limit the delay caused
  * by uneven callback calls to this delay.
+ *
+ * When this setting is enabled, the PJMEDIA_SOUND_BUFFER_COUNT
+ * macro will specify the maximum size of the delay buffer.
  */
 #ifndef PJMEDIA_SOUND_USE_DELAYBUF
 #   define PJMEDIA_SOUND_USE_DELAYBUF	    0
 #endif
 
 
-/**
- * Whenever delay buffer is enabled for sound device,
- * PJMEDIA_SOUND_BUFFER_COUNT is better to be set to 1,
- * because sound callbacks will be called evenly thus 
- * there's no need to have this buffer.
- */
-#if defined(PJMEDIA_SOUND_USE_DELAYBUF) && PJMEDIA_SOUND_USE_DELAYBUF!=0
-#   define PJMEDIA_SOUND_BUFFER_COUNT	    1
-#endif
-
-
 /**
  * Specify number of sound buffers. Larger number is better for sound
  * stability and to accommodate sound devices that are unable to send frames
@@ -124,9 +116,6 @@
  * The setting here currently is used by the conference bridge, the splitter
  * combiner port, and dsound.c.
  *
- * Note that when PJMEDIA_SOUND_USE_DELAYBUF is enabled, it's best to
- * set PJMEDIA_SOUND_BUFFER_COUNT to 1 to reduce voice latency.
- * 
  * Default: 6
  */
 #ifndef PJMEDIA_SOUND_BUFFER_COUNT

pjmedia/src/pjmedia/conference.c

@@ -55,7 +55,13 @@ static FILE *fhnd_rec;
 
 
 #define THIS_FILE	"conference.c"
-#define RX_BUF_COUNT	PJMEDIA_SOUND_BUFFER_COUNT
+
+/* When delay buffer is used, we only need 1 frame buffering */
+#if defined(PJMEDIA_SOUND_USE_DELAYBUF) && PJMEDIA_SOUND_USE_DELAYBUF!=0
+#   define RX_BUF_COUNT	    1
+#else
+#   define RX_BUF_COUNT	    PJMEDIA_SOUND_BUFFER_COUNT
+#endif
 
 #define BYTES_PER_SAMPLE    2
 

pjmedia/src/pjmedia/delaybuf.c

@@ -40,8 +40,25 @@ enum OP
 /* The following macros represent cycles of test. */
 /* Since there are two operations performed (get & put), */
 /* these macros value must be minimum 2 and should be even number */
-#define WAITING_COUNT	8
-#define LEARN_COUNT	8
+#define WAITING_COUNT	4
+#define LEARN_COUNT	16
+
+/* Number of buffers to add to learnt level for additional stability */
+#define SAFE_MARGIN	2
+
+/*
+ * Some experimental data (with SAFE_MARGIN=1):
+ *
+ * System 1:
+ *  - XP, WMME, 10ms ptime, 
+ *  - Sennheiser Headset+USB sound card
+ *  - Stable delaybuf level: 6, on WAITING_COUNT=4 and LEARNING_COUNT=48
+ *
+ * System 2:
+ *  - XP, WMME, 10ms ptime
+ *  - Onboard SoundMAX Digital Audio
+ *  - Stable delaybuf level: 6, on WAITING_COUNT=4 and LEARNING_COUNT=48
+ */
 
 struct pjmedia_delay_buf
 {
@@ -133,8 +150,8 @@ static void update(pjmedia_delay_buf *b, enum OP op)
 	    b->op[other].level = 0;
 	    b->state_count++;
 	    if (b->state_count == LEARN_COUNT) {
-		/* give ONE frame compensation */
-		b->max_level += 1;
+		/* give SAFE_MARGIN compensation for added stability */
+		b->max_level += SAFE_MARGIN;
 		
 		PJ_LOG(5,(b->obj_name,"Delay buffer start running, level=%u",
 		    b->max_level));

pjmedia/src/pjmedia/echo_speex.c

@@ -31,7 +31,7 @@
 #include "echo_internal.h"
 
 #define THIS_FILE	"echo_speex.c"
-#define BUF_COUNT	16
+#define BUF_COUNT	PJMEDIA_SOUND_BUFFER_COUNT
 #define MIN_PREFETCH	2
 #define MAX_PREFETCH	(BUF_COUNT*2/3)
 

pjmedia/src/pjmedia/sound_port.c

@@ -363,7 +363,8 @@ PJ_DEF(pj_status_t) pjmedia_snd_port_create( pj_pool_t *pool,
     
 #if PJMEDIA_SOUND_USE_DELAYBUF
     status = pjmedia_delay_buf_create(pool, "snd_buff", samples_per_frame, 
-				      16, -1, &snd_port->delay_buf);
+				      PJMEDIA_SOUND_BUFFER_COUNT, -1, 
+				      &snd_port->delay_buf);
     PJ_ASSERT_RETURN(status == PJ_SUCCESS, status);
 #else
     PJ_UNUSED_ARG(status);

pjmedia/src/pjmedia/splitcomb.c

@@ -27,7 +27,13 @@
 #define SIGNATURE_PORT	    PJMEDIA_PORT_SIGNATURE('S', 'p', 'C', 'P')
 #define THIS_FILE	    "splitcomb.c"
 #define TMP_SAMP_TYPE	    pj_int16_t
-#define MAX_BUF_CNT	    PJMEDIA_SOUND_BUFFER_COUNT
+
+/* When delay buffer is used, we only need 1 frame buffering */
+#if defined(PJMEDIA_SOUND_USE_DELAYBUF) && PJMEDIA_SOUND_USE_DELAYBUF!=0
+#   define MAX_BUF_CNT	    1
+#else
+#   define MAX_BUF_CNT	    PJMEDIA_SOUND_BUFFER_COUNT
+#endif
 
 #if 0
 #   define TRACE_UP_(x)	PJ_LOG(5,x)