Add OPUS_SET_MIN_BANDWIDTH to set minInternalSampleRate for Silk mode…

… (which is using NARROWBAND)

- Implement OPUS_SET_MIN_BANDWIDTH to OPUS_BANDWIDTH_WIDEBAND to allow configuration of minInternalSampleRate in Silk mode during encoding.
- This enables additional options for decoding, supporting both LACE and NOLACE modes, which require Wideband audio.

include/opus_defines.h

@@ -133,6 +133,8 @@ extern "C" {
 #define OPUS_GET_BITRATE_REQUEST             4003
 #define OPUS_SET_MAX_BANDWIDTH_REQUEST       4004
 #define OPUS_GET_MAX_BANDWIDTH_REQUEST       4005
+#define OPUS_SET_MIN_BANDWIDTH_REQUEST       40050
+#define OPUS_GET_MIN_BANDWIDTH_REQUEST       40051
 #define OPUS_SET_VBR_REQUEST                 4006
 #define OPUS_GET_VBR_REQUEST                 4007
 #define OPUS_SET_BANDWIDTH_REQUEST           4008
@@ -406,6 +408,29 @@ extern "C" {
   * @hideinitializer */
 #define OPUS_GET_MAX_BANDWIDTH(x) OPUS_GET_MAX_BANDWIDTH_REQUEST, __opus_check_int_ptr(x)
 
+ /** Configures the minimum bandpass that the encoder will select automatically.
+	* LACE and NoLACE are currently only applied when the frame size is 20 ms (the default) 
+	* and the bandwidth is at least wideband, to use LACE and NOLACE for low bandwidth
+	* and keep OPUS_AUTO for other bandwidth, we may need OPUS_SET_MIN_BANDWIDTH
+	* @see OPUS_GET_MIN_BANDWIDTH
+	* @param[in] x <tt>opus_int32</tt>: Allowed values:
+	* <dl>
+	* <dt>OPUS_BANDWIDTH_NARROWBAND</dt>    <dd>4 kHz passband</dd>
+	* <dt>OPUS_BANDWIDTH_WIDEBAND</dt>      <dd>8 kHz passband</dd>
+	* </dl>
+	* @hideinitializer */
+#define OPUS_SET_MIN_BANDWIDTH(x) OPUS_SET_MIN_BANDWIDTH_REQUEST, __opus_check_int(x)
+
+/** Gets the encoder's configured minimum allowed bandpass.
+	* @see OPUS_SET_MIN_BANDWIDTH
+	* @param[out] x <tt>opus_int32 *</tt>: Allowed values:
+	* <dl>
+	* <dt>#OPUS_BANDWIDTH_NARROWBAND</dt>    <dd>4 kHz passband</dd>
+	* <dt>#OPUS_BANDWIDTH_WIDEBAND</dt>      <dd>8 kHz passband</dd>
+	* </dl>
+	* @hideinitializer */
+#define OPUS_GET_MIN_BANDWIDTH(x) OPUS_GET_MIN_BANDWIDTH_REQUEST, __opus_check_int_ptr(x)
+
 /** Sets the encoder's bandpass to a specific value.
   * This prevents the encoder from automatically selecting the bandpass based
   * on the available bitrate. If an application knows the bandpass of the input

src/opus_encoder.c

@@ -85,6 +85,7 @@ struct OpusEncoder {
     int          signal_type;
     int          user_bandwidth;
     int          max_bandwidth;
+    int          min_bandwidth;
     int          user_forced_mode;
     int          voice_ratio;
     opus_int32   Fs;
@@ -270,6 +271,7 @@ int opus_encoder_init(OpusEncoder* st, opus_int32 Fs, int channels, int applicat
     st->signal_type = OPUS_AUTO;
     st->user_bandwidth = OPUS_AUTO;
     st->max_bandwidth = OPUS_BANDWIDTH_FULLBAND;
+    st->min_bandwidth = OPUS_BANDWIDTH_NARROWBAND;
     st->force_channels = OPUS_AUTO;
     st->user_forced_mode = OPUS_AUTO;
     st->voice_ratio = -1;
@@ -1476,6 +1478,9 @@ opus_int32 opus_encode_native(OpusEncoder *st, const opus_val16 *pcm, int frame_
            mode transitions. */
         if (bandwidth == OPUS_BANDWIDTH_MEDIUMBAND)
            bandwidth = OPUS_BANDWIDTH_WIDEBAND;
+        /* If have minbandwidth (currently just use wideband to apply LACE & NOLACE)*/
+        if(st->min_bandwidth == OPUS_BANDWIDTH_WIDEBAND && bandwidth < st->min_bandwidth)
+           bandwidth = st->min_bandwidth;
         st->bandwidth = st->auto_bandwidth = bandwidth;
         /* Prevents any transition to SWB/FB until the SILK layer has fully
            switched to WB mode and turned the variable LP filter off */
@@ -1948,7 +1953,13 @@ static opus_int32 opus_encode_frame_native(OpusEncoder *st, const opus_val16 *pc
             /* Don't allow bandwidth reduction at lowest bitrates in hybrid mode */
             st->silk_mode.minInternalSampleRate = 16000;
         } else {
-            st->silk_mode.minInternalSampleRate = 8000;
+            if (st->min_bandwidth == OPUS_BANDWIDTH_WIDEBAND) {
+                st->silk_mode.minInternalSampleRate = 16000;
+            }
+            else {
+                st->silk_mode.minInternalSampleRate = 8000;
+            }
+
         }
 
         st->silk_mode.maxInternalSampleRate = 16000;
@@ -2641,6 +2652,33 @@ int opus_encoder_ctl(OpusEncoder *st, int request, ...)
             *value = st->max_bandwidth;
         }
         break;
+        case OPUS_SET_MIN_BANDWIDTH_REQUEST:
+        {
+            opus_int32 value = va_arg(ap, opus_int32);
+            if (value < OPUS_BANDWIDTH_NARROWBAND || value > OPUS_BANDWIDTH_FULLBAND)
+            {
+                goto bad_arg;
+            }
+            if (value == OPUS_BANDWIDTH_WIDEBAND) {
+                st->min_bandwidth = OPUS_BANDWIDTH_WIDEBAND;
+                st->silk_mode.minInternalSampleRate = 16000;
+            }
+            else {
+                st->min_bandwidth = OPUS_BANDWIDTH_NARROWBAND;
+                st->silk_mode.minInternalSampleRate = 8000;
+            }
+        }
+        break;
+        case OPUS_GET_MIN_BANDWIDTH_REQUEST:
+        {
+            opus_int32* value = va_arg(ap, opus_int32*);
+            if (!value)
+            {
+                goto bad_arg;
+            }
+            *value = st->min_bandwidth;
+        }
+        break;
         case OPUS_SET_BANDWIDTH_REQUEST:
         {
             opus_int32 value = va_arg(ap, opus_int32);