Misc bug fixes

- There was a bug where the decoder resampler was not properly initialized
when fs_kHz == API_fs_kHz. In that case the resampler would continue to
upsample, and the output was corrupt.

- The delay value in the decoder was taken from the state before it was
potentially updated. This caused the decoder to apply the new dalay value one
frame late

- The encoder and decoder states are now updated more consistently, when
the sampling rate changes (pesq liked these changes)

- Properly resetting the side channel encoder and decoder for the first
frame with side coding active again

- Faster updating the "ratio" value in the LR_to_MS() code for large
prediction values means that for certain extreme/artificial input
signals the output looks better

1 files changed, 69 insertions, 36 deletions

diff --git a/silk/decoder_set_fs.c b/silk/decoder_set_fs.c
index c2430f8c..f80470f3 100644
--- a/silk/decoder_set_fs.c
+++ b/silk/decoder_set_fs.c
@@ -31,24 +31,59 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "main.h"
 
+static const int dec_delay_matrix[3][5] = {
+/*SILK API 8  12  16  24  48 */
+/* 8 */   {3, 0, 2, 0, 0},
+/*12 */   {0, 8, 5, 7, 5},
+/*16 */   {0, 0, 8, 5, 5}
+};
+
 /* Set decoder sampling rate */
-void silk_decoder_set_fs(
+opus_int silk_decoder_set_fs(
     silk_decoder_state              *psDec,             /* I/O  Decoder state pointer                       */
-    opus_int                         fs_kHz              /* I    Sampling frequency (kHz)                    */
+    opus_int                         fs_kHz,             /* I    Sampling frequency (kHz)                    */
+    opus_int                         fs_API_Hz           /* I    API Sampling frequency (Hz)                 */
 )
 {
-    opus_int frame_length;
+    opus_int frame_length, ret = 0;
 
     silk_assert( fs_kHz == 8 || fs_kHz == 12 || fs_kHz == 16 );
     silk_assert( psDec->nb_subfr == MAX_NB_SUBFR || psDec->nb_subfr == MAX_NB_SUBFR/2 );
 
+    /* New (sub)frame length */
     psDec->subfr_length = silk_SMULBB( SUB_FRAME_LENGTH_MS, fs_kHz );
     frame_length = silk_SMULBB( psDec->nb_subfr, psDec->subfr_length );
+
+    /* Initialize resampler when switching internal or external sampling frequency */
+    if( psDec->fs_kHz != fs_kHz || psDec->fs_API_hz != fs_API_Hz ) {
+        /* Allocate worst case space for temporary upsampling, 8 to 48 kHz, so a factor 6 */
+        opus_int16 temp_buf[ MAX_FRAME_LENGTH_MS * MAX_API_FS_KHZ ];
+        silk_resampler_state_struct  temp_resampler_state;
+
+        /* New delay value */
+        psDec->delay = dec_delay_matrix[ rateID( silk_SMULBB( fs_kHz, 1000 ) ) ][ rateID( fs_API_Hz ) ];
+        silk_assert( psDec->delay <= MAX_DECODER_DELAY );
+
+        if( psDec->fs_kHz != fs_kHz && psDec->fs_kHz > 0 ) {
+            /* Initialize resampler for temporary resampling of outBuf data to the new internal sampling rate */
+            ret += silk_resampler_init( &temp_resampler_state, silk_SMULBB( psDec->fs_kHz, 1000 ), silk_SMULBB( fs_kHz, 1000 ) );
+
+            /* Temporary resampling of outBuf data to the new internal sampling rate */
+            silk_memcpy( temp_buf, psDec->outBuf, psDec->frame_length * sizeof( opus_int16 ) );
+            ret += silk_resampler( &temp_resampler_state, psDec->outBuf, temp_buf, psDec->frame_length );
+        }
+
+        /* Initialize the resampler for dec_API.c preparing resampling from fs_kHz to API_fs_Hz */
+        ret += silk_resampler_init( &psDec->resampler_state, silk_SMULBB( fs_kHz, 1000 ), fs_API_Hz );
+
+        /* Correct resampler state by resampling buffered data from fs_kHz to API_fs_Hz */
+        ret += silk_resampler( &psDec->resampler_state, temp_buf, psDec->outBuf, frame_length );
+
+        psDec->fs_API_hz = fs_API_Hz;
+    }
+
     if( psDec->fs_kHz != fs_kHz || frame_length != psDec->frame_length ) {
-        psDec->fs_kHz  = fs_kHz;
-        psDec->frame_length   = frame_length;
-        psDec->ltp_mem_length = silk_SMULBB( LTP_MEM_LENGTH_MS, fs_kHz );
-        if( psDec->fs_kHz == 8 ) {
+        if( fs_kHz == 8 ) {
             if( psDec->nb_subfr == MAX_NB_SUBFR ) {
                 psDec->pitch_contour_iCDF = silk_pitch_contour_NB_iCDF;
             } else {
@@ -61,40 +96,38 @@ void silk_decoder_set_fs(
                 psDec->pitch_contour_iCDF = silk_pitch_contour_10_ms_iCDF;
             }
         }
-        if( psDec->fs_kHz == 8 || psDec->fs_kHz == 12 ) {
-            psDec->LPC_order = MIN_LPC_ORDER;
-            psDec->psNLSF_CB = &silk_NLSF_CB_NB_MB;
-        } else {
-            psDec->LPC_order = MAX_LPC_ORDER;
-            psDec->psNLSF_CB = &silk_NLSF_CB_WB;
+        if( psDec->fs_kHz != fs_kHz ) {
+            psDec->ltp_mem_length = silk_SMULBB( LTP_MEM_LENGTH_MS, fs_kHz );
+            if( fs_kHz == 8 || fs_kHz == 12 ) {
+                psDec->LPC_order = MIN_LPC_ORDER;
+                psDec->psNLSF_CB = &silk_NLSF_CB_NB_MB;
+            } else {
+                psDec->LPC_order = MAX_LPC_ORDER;
+                psDec->psNLSF_CB = &silk_NLSF_CB_WB;
+            }
+            if( fs_kHz == 16 ) {
+                psDec->pitch_lag_low_bits_iCDF = silk_uniform8_iCDF;
+            } else if( fs_kHz == 12 ) {
+                psDec->pitch_lag_low_bits_iCDF = silk_uniform6_iCDF;
+            } else if( fs_kHz == 8 ) {
+                psDec->pitch_lag_low_bits_iCDF = silk_uniform4_iCDF;
+            } else {
+                /* unsupported sampling rate */
+                silk_assert( 0 );
+            }
+            psDec->first_frame_after_reset = 1;
+            psDec->lagPrev                 = 100;
+            psDec->LastGainIndex           = 10;
+            psDec->prevSignalType          = TYPE_NO_VOICE_ACTIVITY;
         }
 
-        if( psDec->fs_kHz != fs_kHz)
-        {
-           /* Reset part of the decoder state */
-           silk_memset( psDec->sLPC_Q14_buf, 0,                    sizeof( psDec->sLPC_Q14_buf ) );
-           silk_memset( psDec->outBuf,       0, MAX_FRAME_LENGTH * sizeof( opus_int16 ) );
-           silk_memset( psDec->prevNLSF_Q15, 0,                    sizeof( psDec->prevNLSF_Q15 ) );
-        }
-        psDec->lagPrev                 = 100;
-        psDec->LastGainIndex           = 10;
-        psDec->prevSignalType          = TYPE_NO_VOICE_ACTIVITY;
-        if( psDec->fs_kHz != fs_kHz)
-           psDec->first_frame_after_reset = 1;
-
-        if( fs_kHz == 16 ) {
-            psDec->pitch_lag_low_bits_iCDF = silk_uniform8_iCDF;
-        } else if( fs_kHz == 12 ) {
-            psDec->pitch_lag_low_bits_iCDF = silk_uniform6_iCDF;
-        } else if( fs_kHz == 8 ) {
-            psDec->pitch_lag_low_bits_iCDF = silk_uniform4_iCDF;
-        } else {
-            /* unsupported sampling rate */
-            silk_assert( 0 );
-        }
+        psDec->fs_kHz       = fs_kHz;
+        psDec->frame_length = frame_length;
     }
 
     /* Check that settings are valid */
     silk_assert( psDec->frame_length > 0 && psDec->frame_length <= MAX_FRAME_LENGTH );
+
+    return ret;
 }