3 files changed, 89 insertions, 23 deletions

diff --git a/apps/codecs/aiff_enc.c b/apps/codecs/aiff_enc.c
index 7e085d5721..78c25b8711 100644
--- a/apps/codecs/aiff_enc.c
+++ b/apps/codecs/aiff_enc.c
@@ -72,6 +72,7 @@ struct aiff_header aiff_header =
 /* (*) updated when finalizing file */
 
 static int      num_channels IBSS_ATTR;
+static int      rec_mono_mode IBSS_ATTR;
 static uint32_t sample_rate;
 static uint32_t enc_size;
 static int32_t  err          IBSS_ATTR;
@@ -226,16 +227,37 @@ static inline void sample_to_mono(uint32_t **src, uint32_t **dst)
 {
     int32_t lr1, lr2;
 
-    lr1 = *(*src)++;
-    lr1 = (int16_t)lr1 + (lr1 >> 16) + err;
-    err = lr1 & 1;
-    lr1 >>= 1;
-
-    lr2 = *(*src)++;
-    lr2 = (int16_t)lr2 + (lr2 >> 16) + err;
-    err = lr2 & 1;
-    lr2 >>= 1;
-    *(*dst)++ = swap_odd_even_le32((lr1 << 16) | (uint16_t)lr2);
+    switch(rec_mono_mode)
+    {
+        case 1:
+            /* mono = L */
+            lr1 = *(*src)++;
+            lr1 = lr1 >> 16;
+            lr2 = *(*src)++;
+            lr2 = lr2 >> 16;
+            break;
+        case 2:
+            /* mono = R */
+            lr1 = *(*src)++;
+            lr1 = (int16_t)lr1;
+            lr2 = *(*src)++;
+            lr2 = (int16_t)lr2;
+            break;
+        case 0:
+        default:
+            /* mono = (L+R)/2 */
+            lr1 = *(*src)++;
+            lr1 = (int16_t)lr1 + (lr1 >> 16) + err;
+            err = lr1 & 1;
+            lr1 >>= 1;
+
+            lr2 = *(*src)++;
+            lr2 = (int16_t)lr2 + (lr2 >> 16) + err;
+            err = lr2 & 1;
+            lr2 >>= 1;
+            break;
+    }
+    *(*dst)++ = swap_odd_even_be32((lr1 << 16) | (uint16_t)lr2);
 } /* sample_to_mono */
 
 STATICIRAM void chunk_to_aiff_format(uint32_t *src, uint32_t *dst) ICODE_ATTR;
@@ -316,6 +338,7 @@ static bool init_encoder(void)
 
     sample_rate  = inputs.sample_rate;
     num_channels = inputs.num_channels;
+    rec_mono_mode = inputs.rec_mono_mode;
     err          = 0;
 
     /* configure the buffer system */
diff --git a/apps/codecs/mp3_enc.c b/apps/codecs/mp3_enc.c
index 767a292343..555e981a06 100644
--- a/apps/codecs/mp3_enc.c
+++ b/apps/codecs/mp3_enc.c
@@ -90,6 +90,7 @@ typedef struct {
     int               mean_bits;
     int               ResvSize;
     int               channels;
+    int               rec_mono_mode;
     int               granules;
     long              samplerate;
 } config_t;
@@ -1972,12 +1973,14 @@ static int find_samplerate_index(long freq, int *mp3_type)
 
 bool init_mp3_encoder_engine(int sample_rate,
                              int num_channels,
+                             int rec_mono_mode,
                              struct encoder_config *enc_cfg)
 {
     const bool stereo = num_channels > 1;
     uint32_t avg_byte_per_frame;
 
     cfg.channels      = stereo ? 2 : 1;
+    cfg.rec_mono_mode = rec_mono_mode;
     cfg.mpg.mode      = stereo ? 0 : 3; /* 0=stereo, 3=mono */
     cfg.mpg.smpl_id   = find_samplerate_index(sample_rate, &cfg.mpg.type);
     cfg.samplerate    = sampr_index[cfg.mpg.type][cfg.mpg.smpl_id];
@@ -2093,9 +2096,26 @@ STATICIRAM void to_mono_mm(void)
     inline void to_mono(uint32_t **samp)
     {
         int32_t lr = **samp;
-        int32_t m  = (int16_t)lr + (lr >> 16) + err;
-        err = m & 1;
-        m >>= 1;
+        int32_t m;
+
+        switch(cfg.rec_mono_mode)
+        {
+            case 1:
+                /* mono = L */
+                m  = lr >> 16;
+                break;
+            case 2:
+                /* mono = R */
+                m  = (int16_t)lr;
+                break;
+            case 0:
+            default:
+                /* mono = (L+R)/2 */
+                m  = (int16_t)lr + (lr >> 16) + err;
+                err = m & 1;
+                m >>= 1;
+                break;
+        }
         *(*samp)++ = (m << 16) | (uint16_t)m;
     } /* to_mono */
 
@@ -2517,7 +2537,7 @@ static bool enc_init(void)
         return false;
 
     init_mp3_encoder_engine(inputs.sample_rate, inputs.num_channels,
-                            inputs.config);
+                            inputs.rec_mono_mode, inputs.config);
 
     err = 0;
 
diff --git a/apps/codecs/wav_enc.c b/apps/codecs/wav_enc.c
index a59eff7581..3627808271 100644
--- a/apps/codecs/wav_enc.c
+++ b/apps/codecs/wav_enc.c
@@ -60,6 +60,7 @@ struct riff_header
 #define PCM_CHUNK_SIZE          (PCM_SAMP_PER_CHUNK*4)
 
 static int      num_channels IBSS_ATTR;
+static int      rec_mono_mode IBSS_ATTR;
 static uint32_t sample_rate;
 static uint32_t enc_size;
 static int32_t  err          IBSS_ATTR;
@@ -215,15 +216,36 @@ static inline void sample_to_mono(uint32_t **src, uint32_t **dst)
 {
     int32_t lr1, lr2;
 
-    lr1 = *(*src)++;
-    lr1 = (int16_t)lr1 + (lr1 >> 16) + err;
-    err = lr1 & 1;
-    lr1 >>= 1;
-
-    lr2 = *(*src)++;
-    lr2 = (int16_t)lr2 + (lr2 >> 16) + err;
-    err = lr2 & 1;
-    lr2 >>= 1; 
+    switch(rec_mono_mode)
+    {
+        case 1:
+            /* mono = L */
+            lr1 = *(*src)++;
+            lr1 = lr1 >> 16;
+            lr2 = *(*src)++;
+            lr2 = lr2 >> 16;
+            break;
+        case 2:
+            /* mono = R */
+            lr1 = *(*src)++;
+            lr1 = (uint16_t)lr1;
+            lr2 = *(*src)++;
+            lr2 = (uint16_t)lr2;
+            break;
+        case 0:
+        default:
+            /* mono = (L+R)/2 */
+            lr1 = *(*src)++;
+            lr1 = (int16_t)lr1 + (lr1 >> 16) + err;
+            err = lr1 & 1;
+            lr1 >>= 1;
+
+            lr2 = *(*src)++;
+            lr2 = (int16_t)lr2 + (lr2 >> 16) + err;
+            err = lr2 & 1;
+            lr2 >>= 1;
+            break;
+    }
     *(*dst)++ = swap_odd_even_be32((lr1 << 16) | (uint16_t)lr2);
 } /* sample_to_mono */
 
@@ -305,6 +327,7 @@ static bool init_encoder(void)
 
     sample_rate  = inputs.sample_rate;
     num_channels = inputs.num_channels;
+    rec_mono_mode = inputs.rec_mono_mode;
     err          = 0;
 
     /* configure the buffer system */