Implement ff_scale_vector_to_given_sum_of_squares()
[ffmpeg.git] / libavcodec / qcelpdec.c
index 9040cba..d655529 100644 (file)
  */
 
 /**
- * @file qcelpdec.c
+ * @file libavcodec/qcelpdec.c
  * QCELP decoder
  * @author Reynaldo H. Verdejo Pinochet
  * @remark FFmpeg merging spearheaded by Kenan Gillet
+ * @remark Development mentored by Benjamin Larson
  */
 
 #include <stddef.h>
 
 #include "avcodec.h"
-#include "bitstream.h"
+#include "internal.h"
+#include "get_bits.h"
 
-#include "qcelp.h"
 #include "qcelpdata.h"
 
 #include "celp_math.h"
 #include "celp_filters.h"
+#include "acelp_vectors.h"
+#include "lsp.h"
 
 #undef NDEBUG
 #include <assert.h>
 
-static void weighted_vector_sumf(float *out, const float *in_a,
-                                 const float *in_b, float weight_coeff_a,
-                                 float weight_coeff_b, int length)
+typedef enum
 {
-    int i;
-
-    for(i=0; i<length; i++)
-        out[i] = weight_coeff_a * in_a[i]
-               + weight_coeff_b * in_b[i];
-}
+    I_F_Q = -1,    /*!< insufficient frame quality */
+    SILENCE,
+    RATE_OCTAVE,
+    RATE_QUARTER,
+    RATE_HALF,
+    RATE_FULL
+} qcelp_packet_rate;
+
+typedef struct
+{
+    GetBitContext     gb;
+    qcelp_packet_rate bitrate;
+    QCELPFrame        frame;    /*!< unpacked data frame */
+
+    uint8_t  erasure_count;
+    uint8_t  octave_count;      /*!< count the consecutive RATE_OCTAVE frames */
+    float    prev_lspf[10];
+    float    predictor_lspf[10];/*!< LSP predictor for RATE_OCTAVE and I_F_Q */
+    float    pitch_synthesis_filter_mem[303];
+    float    pitch_pre_filter_mem[303];
+    float    rnd_fir_filter_mem[180];
+    float    formant_mem[170];
+    float    last_codebook_gain;
+    int      prev_g1[2];
+    int      prev_bitrate;
+    float    pitch_gain[4];
+    uint8_t  pitch_lag[4];
+    uint16_t first16bits;
+    uint8_t  warned_buf_mismatch_bitrate;
+} QCELPContext;
 
 /**
  * Initialize the speech codec according to the specification.
@@ -63,8 +88,8 @@ static av_cold int qcelp_decode_init(AVCodecContext *avctx)
 
     avctx->sample_fmt = SAMPLE_FMT_FLT;
 
-    for (i = 0; i < 10; i++)
-        q->prev_lspf[i] = (i + 1) / 11.;
+    for(i=0; i<10; i++)
+        q->prev_lspf[i] = (i+1)/11.;
 
     return 0;
 }
@@ -83,14 +108,14 @@ static av_cold int qcelp_decode_init(AVCodecContext *avctx)
 static int decode_lspf(QCELPContext *q, float *lspf)
 {
     int i;
-    float tmp_lspf;
+    float tmp_lspf, smooth, erasure_coeff;
+    const float *predictors;
 
     if(q->bitrate == RATE_OCTAVE || q->bitrate == I_F_Q)
     {
-        float smooth;
-        const float *predictors = (q->prev_bitrate != RATE_OCTAVE &&
-                                   q->prev_bitrate != I_F_Q ? q->prev_lspf
-                                                            : q->predictor_lspf);
+        predictors = (q->prev_bitrate != RATE_OCTAVE &&
+                       q->prev_bitrate != I_F_Q ?
+                       q->prev_lspf : q->predictor_lspf);
 
         if(q->bitrate == RATE_OCTAVE)
         {
@@ -99,15 +124,15 @@ static int decode_lspf(QCELPContext *q, float *lspf)
             for(i=0; i<10; i++)
             {
                 q->predictor_lspf[i] =
-                             lspf[i] = (q->lspv[i] ?  QCELP_LSP_SPREAD_FACTOR
-                                                   : -QCELP_LSP_SPREAD_FACTOR)
+                             lspf[i] = (q->frame.lspv[i] ?  QCELP_LSP_SPREAD_FACTOR
+                                                         : -QCELP_LSP_SPREAD_FACTOR)
                                      + predictors[i] * QCELP_LSP_OCTAVE_PREDICTOR
                                      + (i + 1) * ((1 - QCELP_LSP_OCTAVE_PREDICTOR)/11);
             }
             smooth = (q->octave_count < 10 ? .875 : 0.1);
         }else
         {
-            float erasure_coeff = QCELP_LSP_OCTAVE_PREDICTOR;
+            erasure_coeff = QCELP_LSP_OCTAVE_PREDICTOR;
 
             assert(q->bitrate == I_F_Q);
 
@@ -133,7 +158,7 @@ static int decode_lspf(QCELPContext *q, float *lspf)
             lspf[i-1] = FFMIN(lspf[i-1], (lspf[i] - QCELP_LSP_SPREAD_FACTOR));
 
         // Low-pass filter the LSP frequencies.
-        weighted_vector_sumf(lspf, lspf, q->prev_lspf, smooth, 1.0-smooth, 10);
+        ff_weighted_vector_sumf(lspf, lspf, q->prev_lspf, smooth, 1.0-smooth, 10);
     }else
     {
         q->octave_count = 0;
@@ -141,8 +166,8 @@ static int decode_lspf(QCELPContext *q, float *lspf)
         tmp_lspf = 0.;
         for(i=0; i<5 ; i++)
         {
-            lspf[2*i+0] = tmp_lspf += qcelp_lspvq[i][q->lspv[i]][0] * 0.0001;
-            lspf[2*i+1] = tmp_lspf += qcelp_lspvq[i][q->lspv[i]][1] * 0.0001;
+            lspf[2*i+0] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][0] * 0.0001;
+            lspf[2*i+1] = tmp_lspf += qcelp_lspvq[i][q->frame.lspv[i]][1] * 0.0001;
         }
 
         // Check for badly received packets.
@@ -165,6 +190,93 @@ static int decode_lspf(QCELPContext *q, float *lspf)
     return 0;
 }
 
+/**
+ * Converts codebook transmission codes to GAIN and INDEX.
+ *
+ * @param q the context
+ * @param gain array holding the decoded gain
+ *
+ * TIA/EIA/IS-733 2.4.6.2
+ */
+static void decode_gain_and_index(QCELPContext  *q,
+                                  float *gain) {
+    int   i, subframes_count, g1[16];
+    float slope;
+
+    if(q->bitrate >= RATE_QUARTER)
+    {
+        switch(q->bitrate)
+        {
+            case RATE_FULL: subframes_count = 16; break;
+            case RATE_HALF: subframes_count = 4;  break;
+            default:        subframes_count = 5;
+        }
+        for(i=0; i<subframes_count; i++)
+        {
+            g1[i] = 4 * q->frame.cbgain[i];
+            if(q->bitrate == RATE_FULL && !((i+1) & 3))
+            {
+                g1[i] += av_clip((g1[i-1] + g1[i-2] + g1[i-3]) / 3 - 6, 0, 32);
+            }
+
+            gain[i] = qcelp_g12ga[g1[i]];
+
+            if(q->frame.cbsign[i])
+            {
+                gain[i] = -gain[i];
+                q->frame.cindex[i] = (q->frame.cindex[i]-89) & 127;
+            }
+        }
+
+        q->prev_g1[0] = g1[i-2];
+        q->prev_g1[1] = g1[i-1];
+        q->last_codebook_gain = qcelp_g12ga[g1[i-1]];
+
+        if(q->bitrate == RATE_QUARTER)
+        {
+            // Provide smoothing of the unvoiced excitation energy.
+            gain[7] =     gain[4];
+            gain[6] = 0.4*gain[3] + 0.6*gain[4];
+            gain[5] =     gain[3];
+            gain[4] = 0.8*gain[2] + 0.2*gain[3];
+            gain[3] = 0.2*gain[1] + 0.8*gain[2];
+            gain[2] =     gain[1];
+            gain[1] = 0.6*gain[0] + 0.4*gain[1];
+        }
+    }else if (q->bitrate != SILENCE)
+    {
+        if(q->bitrate == RATE_OCTAVE)
+        {
+            g1[0] = 2 * q->frame.cbgain[0]
+                  + av_clip((q->prev_g1[0] + q->prev_g1[1]) / 2 - 5, 0, 54);
+            subframes_count = 8;
+        }else
+        {
+            assert(q->bitrate == I_F_Q);
+
+            g1[0] = q->prev_g1[1];
+            switch(q->erasure_count)
+            {
+                case 1 : break;
+                case 2 : g1[0] -= 1; break;
+                case 3 : g1[0] -= 2; break;
+                default: g1[0] -= 6;
+            }
+            if(g1[0] < 0)
+                g1[0] = 0;
+            subframes_count = 4;
+        }
+        // This interpolation is done to produce smoother background noise.
+        slope = 0.5*(qcelp_g12ga[g1[0]] - q->last_codebook_gain) / subframes_count;
+        for(i=1; i<=subframes_count; i++)
+            gain[i-1] = q->last_codebook_gain + slope * i;
+
+        q->last_codebook_gain = gain[i-2];
+        q->prev_g1[0] = q->prev_g1[1];
+        q->prev_g1[1] = g1[0];
+    }
+}
+
 /**
  * If the received packet is Rate 1/4 a further sanity check is made of the
  * codebook gain.
@@ -176,11 +288,11 @@ static int decode_lspf(QCELPContext *q, float *lspf)
  */
 static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain)
 {
-    int i, prev_diff=0;
+    int i, diff, prev_diff=0;
 
     for(i=1; i<5; i++)
     {
-        int diff = cbgain[i] - cbgain[i-1];
+        diff = cbgain[i] - cbgain[i-1];
         if(FFABS(diff) > 10)
             return -1;
         else if(FFABS(diff - prev_diff) > 12)
@@ -211,7 +323,7 @@ static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain)
  * @param gain array holding the 4 pitch subframe gain values
  * @param cdn_vector array for the generated scaled codebook vector
  */
-static void compute_svector(const QCELPContext *q, const float *gain,
+static void compute_svector(QCELPContext *q, const float *gain,
                             float *cdn_vector)
 {
     int      i, j, k;
@@ -224,7 +336,7 @@ static void compute_svector(const QCELPContext *q, const float *gain,
             for(i=0; i<16; i++)
             {
                 tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
-                cindex = -q->cindex[i];
+                cindex = -q->frame.cindex[i];
                 for(j=0; j<10; j++)
                     *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cindex++ & 127];
             }
@@ -233,17 +345,17 @@ static void compute_svector(const QCELPContext *q, const float *gain,
             for(i=0; i<4; i++)
             {
                 tmp_gain = gain[i] * QCELP_RATE_HALF_CODEBOOK_RATIO;
-                cindex = -q->cindex[i];
+                cindex = -q->frame.cindex[i];
                 for (j = 0; j < 40; j++)
                 *cdn_vector++ = tmp_gain * qcelp_rate_half_codebook[cindex++ & 127];
             }
         break;
         case RATE_QUARTER:
-            cbseed = (0x0003 & q->lspv[4])<<14 |
-                     (0x003F & q->lspv[3])<< 8 |
-                     (0x0060 & q->lspv[2])<< 1 |
-                     (0x0007 & q->lspv[1])<< 3 |
-                     (0x0038 & q->lspv[0])>> 3 ;
+            cbseed = (0x0003 & q->frame.lspv[4])<<14 |
+                     (0x003F & q->frame.lspv[3])<< 8 |
+                     (0x0060 & q->frame.lspv[2])<< 1 |
+                     (0x0007 & q->frame.lspv[1])<< 3 |
+                     (0x0038 & q->frame.lspv[0])>> 3 ;
             rnd = q->rnd_fir_filter_mem + 20;
             for(i=0; i<8; i++)
             {
@@ -287,6 +399,9 @@ static void compute_svector(const QCELPContext *q, const float *gain,
                     *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cbseed++ & 127];
             }
         break;
+        case SILENCE:
+            memset(cdn_vector, 0, 160 * sizeof(float));
+        break;
     }
 }
 
@@ -297,29 +412,18 @@ static void compute_svector(const QCELPContext *q, const float *gain,
  * @param v_in gain-controlled vector
  * @param v_ref vector to control gain of
  *
- * FIXME: If v_ref is a zero vector, it energy is zero
- *        and the behavior of the gain control is
- *        undefined in the specs.
- *
- * TIA/EIA/IS-733 2.4.8.3-2/3/4/5, 2.4.8.6
+ * TIA/EIA/IS-733 2.4.8.3, 2.4.8.6
  */
 static void apply_gain_ctrl(float *v_out, const float *v_ref,
                             const float *v_in)
 {
-    int   i, j, len;
-    float scalefactor;
+    int i;
 
-    for(i=0, j=0; i<4; i++)
-    {
-        scalefactor = ff_dot_productf(v_in + j, v_in + j, 40);
-        if(scalefactor)
-            scalefactor = sqrt(ff_dot_productf(v_ref + j, v_ref + j, 40)
-                        / scalefactor);
-        else
-            av_log_missing_feature(NULL, "Zero energy for gain control", 1);
-        for(len=j+40; j<len; j++)
-            v_out[j] = scalefactor * v_in[j];
-    }
+    for (i = 0; i < 160; i += 40)
+        ff_scale_vector_to_given_sum_of_squares(v_out + i, v_in + i,
+                                                ff_dot_productf(v_ref + i,
+                                                                v_ref + i, 40),
+                                                40);
 }
 
 /**
@@ -380,11 +484,114 @@ static const float *do_pitchfilter(float memory[303], const float v_in[160],
     return memory + 143;
 }
 
+/**
+ * Apply pitch synthesis filter and pitch prefilter to the scaled codebook vector.
+ * TIA/EIA/IS-733 2.4.5.2, 2.4.8.7.2
+ *
+ * @param q the context
+ * @param cdn_vector the scaled codebook vector
+ */
+static void apply_pitch_filters(QCELPContext *q, float *cdn_vector)
+{
+    int         i;
+    const float *v_synthesis_filtered, *v_pre_filtered;
+
+    if(q->bitrate >= RATE_HALF ||
+       q->bitrate == SILENCE ||
+       (q->bitrate == I_F_Q && (q->prev_bitrate >= RATE_HALF)))
+    {
+
+        if(q->bitrate >= RATE_HALF)
+        {
+
+            // Compute gain & lag for the whole frame.
+            for(i=0; i<4; i++)
+            {
+                q->pitch_gain[i] = q->frame.plag[i] ? (q->frame.pgain[i] + 1) * 0.25 : 0.0;
+
+                q->pitch_lag[i] = q->frame.plag[i] + 16;
+            }
+        }else
+        {
+            float max_pitch_gain;
+
+            if (q->bitrate == I_F_Q)
+            {
+                  if (q->erasure_count < 3)
+                      max_pitch_gain = 0.9 - 0.3 * (q->erasure_count - 1);
+                  else
+                      max_pitch_gain = 0.0;
+            }else
+            {
+                assert(q->bitrate == SILENCE);
+                max_pitch_gain = 1.0;
+            }
+            for(i=0; i<4; i++)
+                q->pitch_gain[i] = FFMIN(q->pitch_gain[i], max_pitch_gain);
+
+            memset(q->frame.pfrac, 0, sizeof(q->frame.pfrac));
+        }
+
+        // pitch synthesis filter
+        v_synthesis_filtered = do_pitchfilter(q->pitch_synthesis_filter_mem,
+                                              cdn_vector, q->pitch_gain,
+                                              q->pitch_lag, q->frame.pfrac);
+
+        // pitch prefilter update
+        for(i=0; i<4; i++)
+            q->pitch_gain[i] = 0.5 * FFMIN(q->pitch_gain[i], 1.0);
+
+        v_pre_filtered = do_pitchfilter(q->pitch_pre_filter_mem,
+                                        v_synthesis_filtered,
+                                        q->pitch_gain, q->pitch_lag,
+                                        q->frame.pfrac);
+
+        apply_gain_ctrl(cdn_vector, v_synthesis_filtered, v_pre_filtered);
+    }else
+    {
+        memcpy(q->pitch_synthesis_filter_mem, cdn_vector + 17,
+               143 * sizeof(float));
+        memcpy(q->pitch_pre_filter_mem, cdn_vector + 17, 143 * sizeof(float));
+        memset(q->pitch_gain, 0, sizeof(q->pitch_gain));
+        memset(q->pitch_lag,  0, sizeof(q->pitch_lag));
+    }
+}
+
+/**
+ * Reconstructs LPC coefficients from the line spectral pair frequencies
+ * and performs bandwidth expansion.
+ *
+ * @param lspf line spectral pair frequencies
+ * @param lpc linear predictive coding coefficients
+ *
+ * @note: bandwidth_expansion_coeff could be precalculated into a table
+ *        but it seems to be slower on x86
+ *
+ * TIA/EIA/IS-733 2.4.3.3.5
+ */
+static void lspf2lpc(const float *lspf, float *lpc)
+{
+    double lsp[10];
+    double bandwidth_expansion_coeff = QCELP_BANDWIDTH_EXPANSION_COEFF;
+    int   i;
+
+    for (i=0; i<10; i++)
+        lsp[i] = cos(M_PI * lspf[i]);
+
+    ff_acelp_lspd2lpc(lsp, lpc);
+
+    for (i=0; i<10; i++)
+    {
+        lpc[i] *= bandwidth_expansion_coeff;
+        bandwidth_expansion_coeff *= QCELP_BANDWIDTH_EXPANSION_COEFF;
+    }
+}
+
 /**
  * Interpolates LSP frequencies and computes LPC coefficients
  * for a given bitrate & pitch subframe.
  *
- * TIA/EIA/IS-733 2.4.3.3.4
+ * TIA/EIA/IS-733 2.4.3.3.4, 2.4.8.7.2
  *
  * @param q the context
  * @param curr_lspf LSP frequencies vector of the current frame
@@ -406,30 +613,79 @@ void interpolate_lpc(QCELPContext *q, const float *curr_lspf, float *lpc,
 
     if(weight != 1.0)
     {
-        weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
-                             weight, 1.0 - weight, 10);
-        qcelp_lspf2lpc(interpolated_lspf, lpc);
-    }else if(q->bitrate >= RATE_QUARTER || (q->bitrate == I_F_Q && !subframe_num))
-        qcelp_lspf2lpc(curr_lspf, lpc);
+        ff_weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf,
+                                weight, 1.0 - weight, 10);
+        lspf2lpc(interpolated_lspf, lpc);
+    }else if(q->bitrate >= RATE_QUARTER ||
+             (q->bitrate == I_F_Q && !subframe_num))
+        lspf2lpc(curr_lspf, lpc);
+    else if(q->bitrate == SILENCE && !subframe_num)
+        lspf2lpc(q->prev_lspf, lpc);
 }
 
-static int buf_size2bitrate(const int buf_size)
+static qcelp_packet_rate buf_size2bitrate(const int buf_size)
 {
     switch(buf_size)
     {
-        case 35:
-            return RATE_FULL;
-        case 17:
-            return RATE_HALF;
-        case  8:
-            return RATE_QUARTER;
-        case  4:
-            return RATE_OCTAVE;
-        case  1:
-            return SILENCE;
+        case 35: return RATE_FULL;
+        case 17: return RATE_HALF;
+        case  8: return RATE_QUARTER;
+        case  4: return RATE_OCTAVE;
+        case  1: return SILENCE;
     }
 
-    return -1;
+    return I_F_Q;
+}
+
+/**
+ * Determine the bitrate from the frame size and/or the first byte of the frame.
+ *
+ * @param avctx the AV codec context
+ * @param buf_size length of the buffer
+ * @param buf the bufffer
+ *
+ * @return the bitrate on success,
+ *         I_F_Q  if the bitrate cannot be satisfactorily determined
+ *
+ * TIA/EIA/IS-733 2.4.8.7.1
+ */
+static qcelp_packet_rate determine_bitrate(AVCodecContext *avctx, const int buf_size,
+                             const uint8_t **buf)
+{
+    qcelp_packet_rate bitrate;
+
+    if((bitrate = buf_size2bitrate(buf_size)) >= 0)
+    {
+        if(bitrate > **buf)
+        {
+            QCELPContext *q = avctx->priv_data;
+            if (!q->warned_buf_mismatch_bitrate)
+            {
+            av_log(avctx, AV_LOG_WARNING,
+                   "Claimed bitrate and buffer size mismatch.\n");
+                q->warned_buf_mismatch_bitrate = 1;
+            }
+            bitrate = **buf;
+        }else if(bitrate < **buf)
+        {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Buffer is too small for the claimed bitrate.\n");
+            return I_F_Q;
+        }
+        (*buf)++;
+    }else if((bitrate = buf_size2bitrate(buf_size + 1)) >= 0)
+    {
+        av_log(avctx, AV_LOG_WARNING,
+               "Bitrate byte is missing, guessing the bitrate from packet size.\n");
+    }else
+        return I_F_Q;
+
+    if(bitrate == SILENCE)
+    {
+        //FIXME: Remove experimental warning when tested with samples.
+        av_log_ask_for_sample(avctx, "'Blank frame handling is experimental.");
+    }
+    return bitrate;
 }
 
 static void warn_insufficient_frame_quality(AVCodecContext *avctx,
@@ -439,6 +695,121 @@ static void warn_insufficient_frame_quality(AVCodecContext *avctx,
            message);
 }
 
+static int qcelp_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
+                              AVPacket *avpkt)
+{
+    const uint8_t *buf = avpkt->data;
+    int buf_size = avpkt->size;
+    QCELPContext *q = avctx->priv_data;
+    float *outbuffer = data;
+    int   i;
+    float quantized_lspf[10], lpc[10];
+    float gain[16];
+    float *formant_mem;
+
+    if((q->bitrate = determine_bitrate(avctx, buf_size, &buf)) == I_F_Q)
+    {
+        warn_insufficient_frame_quality(avctx, "bitrate cannot be determined.");
+        goto erasure;
+    }
+
+    if(q->bitrate == RATE_OCTAVE &&
+       (q->first16bits = AV_RB16(buf)) == 0xFFFF)
+    {
+        warn_insufficient_frame_quality(avctx, "Bitrate is 1/8 and first 16 bits are on.");
+        goto erasure;
+    }
+
+    if(q->bitrate > SILENCE)
+    {
+        const QCELPBitmap *bitmaps     = qcelp_unpacking_bitmaps_per_rate[q->bitrate];
+        const QCELPBitmap *bitmaps_end = qcelp_unpacking_bitmaps_per_rate[q->bitrate]
+                                       + qcelp_unpacking_bitmaps_lengths[q->bitrate];
+        uint8_t           *unpacked_data = (uint8_t *)&q->frame;
+
+        init_get_bits(&q->gb, buf, 8*buf_size);
+
+        memset(&q->frame, 0, sizeof(QCELPFrame));
+
+        for(; bitmaps < bitmaps_end; bitmaps++)
+            unpacked_data[bitmaps->index] |= get_bits(&q->gb, bitmaps->bitlen) << bitmaps->bitpos;
+
+        // Check for erasures/blanks on rates 1, 1/4 and 1/8.
+        if(q->frame.reserved)
+        {
+            warn_insufficient_frame_quality(avctx, "Wrong data in reserved frame area.");
+            goto erasure;
+        }
+        if(q->bitrate == RATE_QUARTER &&
+           codebook_sanity_check_for_rate_quarter(q->frame.cbgain))
+        {
+            warn_insufficient_frame_quality(avctx, "Codebook gain sanity check failed.");
+            goto erasure;
+        }
+
+        if(q->bitrate >= RATE_HALF)
+        {
+            for(i=0; i<4; i++)
+            {
+                if(q->frame.pfrac[i] && q->frame.plag[i] >= 124)
+                {
+                    warn_insufficient_frame_quality(avctx, "Cannot initialize pitch filter.");
+                    goto erasure;
+                }
+            }
+        }
+    }
+
+    decode_gain_and_index(q, gain);
+    compute_svector(q, gain, outbuffer);
+
+    if(decode_lspf(q, quantized_lspf) < 0)
+    {
+        warn_insufficient_frame_quality(avctx, "Badly received packets in frame.");
+        goto erasure;
+    }
+
+
+    apply_pitch_filters(q, outbuffer);
+
+    if(q->bitrate == I_F_Q)
+    {
+erasure:
+        q->bitrate = I_F_Q;
+        q->erasure_count++;
+        decode_gain_and_index(q, gain);
+        compute_svector(q, gain, outbuffer);
+        decode_lspf(q, quantized_lspf);
+        apply_pitch_filters(q, outbuffer);
+    }else
+        q->erasure_count = 0;
+
+    formant_mem = q->formant_mem + 10;
+    for(i=0; i<4; i++)
+    {
+        interpolate_lpc(q, quantized_lspf, lpc, i);
+        ff_celp_lp_synthesis_filterf(formant_mem, lpc, outbuffer + i * 40, 40,
+                                     10);
+        formant_mem += 40;
+    }
+    memcpy(q->formant_mem, q->formant_mem + 160, 10 * sizeof(float));
+
+    // FIXME: postfilter and final gain control should be here.
+    // TIA/EIA/IS-733 2.4.8.6
+
+    formant_mem = q->formant_mem + 10;
+    for(i=0; i<160; i++)
+        *outbuffer++ = av_clipf(*formant_mem++, QCELP_CLIP_LOWER_BOUND,
+                                QCELP_CLIP_UPPER_BOUND);
+
+    memcpy(q->prev_lspf, quantized_lspf, sizeof(q->prev_lspf));
+    q->prev_bitrate = q->bitrate;
+
+    *data_size = 160 * sizeof(*outbuffer);
+
+    return *data_size;
+}
+
 AVCodec qcelp_decoder =
 {
     .name   = "qcelp",