libopenh264enc: Return a more sensible error code in some init failure paths
[ffmpeg.git] / libavcodec / qcelpdec.c
index 1dff368..e9e7347 100644 (file)
  * QCELP decoder
  * Copyright (c) 2007 Reynaldo H. Verdejo Pinochet
  *
- * This file is part of FFmpeg.
+ * This file is part of Libav.
  *
- * FFmpeg is free software; you can redistribute it and/or
+ * Libav is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
- * FFmpeg is distributed in the hope that it will be useful,
+ * Libav is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
+ * License along with Libav; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**
- * @file qcelpdec.c
+ * @file
  * QCELP decoder
  * @author Reynaldo H. Verdejo Pinochet
- * @remark FFmpeg merging spearheaded by Kenan Gillet
+ * @remark Libav merging spearheaded by Kenan Gillet
+ * @remark Development mentored by Benjamin Larson
  */
 
 #include <stddef.h>
 
+#include "libavutil/channel_layout.h"
+#include "libavutil/float_dsp.h"
 #include "avcodec.h"
-#include "bitstream.h"
-
-#include "qcelp.h"
+#include "internal.h"
+#include "get_bits.h"
 #include "qcelpdata.h"
-
-#include "celp_math.h"
 #include "celp_filters.h"
+#include "acelp_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)
-{
-    int i;
-
-    for(i=0; i<length; i++)
-        out[i] = weight_coeff_a * in_a[i]
-               + weight_coeff_b * in_b[i];
-}
+typedef enum {
+    I_F_Q = -1,    /**< insufficient frame quality */
+    SILENCE,
+    RATE_OCTAVE,
+    RATE_QUARTER,
+    RATE_HALF,
+    RATE_FULL
+} qcelp_packet_rate;
+
+typedef struct QCELPContext {
+    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;
+
+    /* postfilter */
+    float    postfilter_synth_mem[10];
+    float    postfilter_agc_mem;
+    float    postfilter_tilt_mem;
+} QCELPContext;
 
 /**
  * Initialize the speech codec according to the specification.
  *
  * TIA/EIA/IS-733 2.4.9
  */
-static av_cold int qcelp_decode_init(AVCodecContext *avctx) {
+static av_cold int qcelp_decode_init(AVCodecContext *avctx)
+{
     QCELPContext *q = avctx->priv_data;
     int i;
 
-    avctx->sample_fmt = SAMPLE_FMT_FLT;
+    avctx->channels       = 1;
+    avctx->channel_layout = AV_CH_LAYOUT_MONO;
+    avctx->sample_fmt     = AV_SAMPLE_FMT_FLT;
 
     for (i = 0; i < 10; i++)
-        q->prev_lspf[i] = (i + 1) / 11.;
+        q->prev_lspf[i] = (i + 1) / 11.0;
 
     return 0;
 }
 
 /**
- * Decodes the 10 quantized LSP frequencies from the LSPV/LSP
- * transmission codes of any bitrate and checks for badly received packets.
+ * Decode the 10 quantized LSP frequencies from the LSPV/LSP
+ * transmission codes of any bitrate and check for badly received packets.
  *
  * @param q the context
  * @param lspf line spectral pair frequencies
@@ -79,41 +110,40 @@ static av_cold int qcelp_decode_init(AVCodecContext *avctx) {
  *
  * TIA/EIA/IS-733 2.4.3.2.6.2-2, 2.4.8.7.3
  */
-static int decode_lspf(QCELPContext *q,
-                       float *lspf) {
+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);
+    if (q->bitrate == RATE_OCTAVE || q->bitrate == I_F_Q) {
+        predictors = q->prev_bitrate != RATE_OCTAVE &&
+                     q->prev_bitrate != I_F_Q ? q->prev_lspf
+                                              : q->predictor_lspf;
 
         if (q->bitrate == RATE_OCTAVE) {
             q->octave_count++;
 
             for (i = 0; i < 10; i++) {
                 q->predictor_lspf[i] =
-                             lspf[i] = (q->lspv[i] ?  QCELP_LSP_SPREAD_FACTOR
-                                                   : -QCELP_LSP_SPREAD_FACTOR)
-                                     + predictors[i] * QCELP_LSP_OCTAVE_PREDICTOR
-                                     + (i + 1) * ((1 - QCELP_LSP_OCTAVE_PREDICTOR)/11);
+                             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);
+            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);
 
             if (q->erasure_count > 1)
-                erasure_coeff *= (q->erasure_count < 4 ? 0.9 : 0.7);
+                erasure_coeff *= q->erasure_count < 4 ? 0.9 : 0.7;
 
             for (i = 0; i < 10; i++) {
                 q->predictor_lspf[i] =
-                             lspf[i] = (i + 1) * ( 1 - erasure_coeff)/11
-                                     + erasure_coeff * predictors[i];
+                             lspf[i] = (i + 1) * (1 - erasure_coeff) / 11 +
+                                       erasure_coeff * predictors[i];
             }
             smooth = 0.125;
         }
@@ -121,35 +151,35 @@ static int decode_lspf(QCELPContext *q,
         // Check the stability of the LSP frequencies.
         lspf[0] = FFMAX(lspf[0], QCELP_LSP_SPREAD_FACTOR);
         for (i = 1; i < 10; i++)
-            lspf[i] = FFMAX(lspf[i], (lspf[i-1] + QCELP_LSP_SPREAD_FACTOR));
+            lspf[i] = FFMAX(lspf[i], lspf[i - 1] + QCELP_LSP_SPREAD_FACTOR);
 
-        lspf[9] = FFMIN(lspf[9], (1.0 - QCELP_LSP_SPREAD_FACTOR));
+        lspf[9] = FFMIN(lspf[9], 1.0 - QCELP_LSP_SPREAD_FACTOR);
         for (i = 9; i > 0; i--)
-            lspf[i-1] = FFMIN(lspf[i-1], (lspf[i] - QCELP_LSP_SPREAD_FACTOR));
+            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;
 
-        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;
+        tmp_lspf = 0.0;
+        for (i = 0; i < 5; i++) {
+            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.
         if (q->bitrate == RATE_QUARTER) {
-            if (lspf[9] <= .70 || lspf[9] >=  .97)
+            if (lspf[9] <= .70 || lspf[9] >= .97)
                 return -1;
             for (i = 3; i < 10; i++)
-                if (fabs(lspf[i] - lspf[i-2]) < .08)
+                if (fabs(lspf[i] - lspf[i - 2]) < .08)
                     return -1;
         } else {
             if (lspf[9] <= .66 || lspf[9] >= .985)
                 return -1;
             for (i = 4; i < 10; i++)
-                if (fabs(lspf[i] - lspf[i-4]) < .0931)
+                if (fabs(lspf[i] - lspf[i - 4]) < .0931)
                     return -1;
         }
     }
@@ -157,29 +187,108 @@ static int decode_lspf(QCELPContext *q,
 }
 
 /**
- * If the received packet is Rate 1/4 a further sanity check is made of the codebook gain.
+ * Convert 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.
  *
  * @param cbgain the unpacked cbgain array
  * @return -1 if the sanity check fails, 0 otherwise
  *
  * TIA/EIA/IS-733 2.4.8.7.3
  */
-static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain) {
-   int i, prev_diff=0;
-
-   for (i = 1; i < 5; i++) {
-       int diff = cbgain[i] - cbgain[i-1];
-       if (FFABS(diff) > 10)
-           return -1;
-       else if (FFABS(diff - prev_diff) > 12)
-           return -1;
-       prev_diff = diff;
-   }
-   return 0;
+static int codebook_sanity_check_for_rate_quarter(const uint8_t *cbgain)
+{
+    int i, diff, prev_diff = 0;
+
+    for (i = 1; i < 5; i++) {
+        diff = cbgain[i] - cbgain[i-1];
+        if (FFABS(diff) > 10)
+            return -1;
+        else if (FFABS(diff - prev_diff) > 12)
+            return -1;
+        prev_diff = diff;
+    }
+    return 0;
 }
 
 /**
- * Computes the scaled codebook vector Cdn From INDEX and GAIN
+ * Compute the scaled codebook vector Cdn From INDEX and GAIN
  * for all rates.
  *
  * The specification lacks some information here.
@@ -199,18 +308,18 @@ 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,
-                            float *cdn_vector) {
-    int      i, j, k;
+static void compute_svector(QCELPContext *q, const float *gain,
+                            float *cdn_vector)
+{
+    int i, j, k;
     uint16_t cbseed, cindex;
-    float    *rnd, tmp_gain, fir_filter_value;
+    float *rnd, tmp_gain, fir_filter_value;
 
     switch (q->bitrate) {
     case RATE_FULL:
         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];
         }
@@ -218,43 +327,45 @@ static void compute_svector(const QCELPContext *q,
     case RATE_HALF:
         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 ;
-        rnd = q->rnd_fir_filter_mem + 20;
+        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++) {
             tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
             for (k = 0; k < 20; k++) {
                 cbseed = 521 * cbseed + 259;
-                *rnd = (int16_t)cbseed;
+                *rnd   = (int16_t) cbseed;
 
-                // FIR filter
+                    // FIR filter
                 fir_filter_value = 0.0;
                 for (j = 0; j < 10; j++)
-                    fir_filter_value += qcelp_rnd_fir_coefs[j ] * (rnd[-j ] + rnd[-20+j]);
-                fir_filter_value     += qcelp_rnd_fir_coefs[10] *  rnd[-10];
+                    fir_filter_value += qcelp_rnd_fir_coefs[j] *
+                                        (rnd[-j] + rnd[-20+j]);
 
-                *cdn_vector++ = tmp_gain * fir_filter_value;
+                fir_filter_value += qcelp_rnd_fir_coefs[10] * rnd[-10];
+                *cdn_vector++     = tmp_gain * fir_filter_value;
                 rnd++;
             }
         }
-        memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160, 20 * sizeof(float));
+        memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160,
+               20 * sizeof(float));
         break;
     case RATE_OCTAVE:
         cbseed = q->first16bits;
         for (i = 0; i < 8; i++) {
             tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
             for (j = 0; j < 20; j++) {
-                cbseed = 521 * cbseed + 259;
-                *cdn_vector++ = tmp_gain * (int16_t)cbseed;
+                cbseed        = 521 * cbseed + 259;
+                *cdn_vector++ = tmp_gain * (int16_t) cbseed;
             }
         }
         break;
@@ -266,6 +377,9 @@ static void compute_svector(const QCELPContext *q,
                 *cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cbseed++ & 127];
         }
         break;
+    case SILENCE:
+        memset(cdn_vector, 0, 160 * sizeof(float));
+        break;
     }
 }
 
@@ -276,26 +390,15 @@ static void compute_svector(const QCELPContext *q,
  * @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;
-
-    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];
+static void apply_gain_ctrl(float *v_out, const float *v_ref, const float *v_in)
+{
+    int i;
+
+    for (i = 0; i < 160; i += 40) {
+        float res = avpriv_scalarproduct_float_c(v_ref + i, v_ref + i, 40);
+        ff_scale_vector_to_given_sum_of_squares(v_out + i, v_in + i, res, 40);
     }
 }
 
@@ -311,7 +414,8 @@ static void apply_gain_ctrl(float *v_out,
  * @param lag per-subframe lag array, each element is
  *        - between 16 and 143 if its corresponding pfrac is 0,
  *        - between 16 and 139 otherwise
- * @param pfrac per-subframe boolean array, 1 if the lag is fractional, 0 otherwise
+ * @param pfrac per-subframe boolean array, 1 if the lag is fractional, 0
+ *        otherwise
  *
  * @return filter output vector
  */
@@ -319,24 +423,20 @@ static const float *do_pitchfilter(float memory[303], const float v_in[160],
                                    const float gain[4], const uint8_t *lag,
                                    const uint8_t pfrac[4])
 {
-    int         i, j;
-    float       *v_lag, *v_out;
+    int i, j;
+    float *v_lag, *v_out;
     const float *v_len;
 
     v_out = memory + 143; // Output vector starts at memory[143].
 
-    for(i=0; i<4; i++)
-    {
-        if(gain[i])
-        {
+    for (i = 0; i < 4; i++) {
+        if (gain[i]) {
             v_lag = memory + 143 + 40 * i - lag[i];
-            for(v_len=v_in+40; v_in<v_len; v_in++)
-            {
-                if(pfrac[i]) // If it is a fractional lag...
-                {
-                    for(j=0, *v_out=0.; j<4; j++)
-                        *v_out += qcelp_hammsinc_table[j] * (v_lag[j-4] + v_lag[3-j]);
-                }else
+            for (v_len = v_in + 40; v_in < v_len; v_in++) {
+                if (pfrac[i]) { // If it is a fractional lag...
+                    for (j = 0, *v_out = 0.0; j < 4; j++)
+                        *v_out += qcelp_hammsinc_table[j] * (v_lag[j - 4] + v_lag[3 - j]);
+                } else
                     *v_out = *v_lag;
 
                 *v_out = *v_in + gain[i] * *v_out;
@@ -344,8 +444,7 @@ static const float *do_pitchfilter(float memory[303], const float v_in[160],
                 v_lag++;
                 v_out++;
             }
-        }else
-        {
+        } else {
             memcpy(v_out, v_in, 40 * sizeof(float));
             v_in  += 40;
             v_out += 40;
@@ -357,71 +456,344 @@ static const float *do_pitchfilter(float memory[303], const float v_in[160],
 }
 
 /**
- * Interpolates LSP frequencies and computes LPC coefficients
+ * 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));
+    }
+}
+
+/**
+ * Reconstruct LPC coefficients from the line spectral pair frequencies
+ * and perform 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, 5);
+
+    for (i = 0; i < 10; i++) {
+        lpc[i]                    *= bandwidth_expansion_coeff;
+        bandwidth_expansion_coeff *= QCELP_BANDWIDTH_EXPANSION_COEFF;
+    }
+}
+
+/**
+ * Interpolate LSP frequencies and compute 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
  * @param lpc float vector for the resulting LPC
  * @param subframe_num frame number in decoded stream
  */
-void interpolate_lpc(QCELPContext *q, const float *curr_lspf, float *lpc,
-                     const int subframe_num)
+static void interpolate_lpc(QCELPContext *q, const float *curr_lspf,
+                            float *lpc, const int subframe_num)
 {
     float interpolated_lspf[10];
     float weight;
 
-    if(q->bitrate >= RATE_QUARTER)
+    if (q->bitrate >= RATE_QUARTER)
         weight = 0.25 * (subframe_num + 1);
-    else if(q->bitrate == RATE_OCTAVE && !subframe_num)
+    else if (q->bitrate == RATE_OCTAVE && !subframe_num)
         weight = 0.625;
     else
         weight = 1.0;
 
-    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);
+    if (weight != 1.0) {
+        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;
+    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;
     }
 
-    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 buffer
+ *
+ * @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 this warning when tested with samples.
+        avpriv_request_sample(avctx, "Blank frame handling");
+    }
+    return bitrate;
 }
 
 static void warn_insufficient_frame_quality(AVCodecContext *avctx,
                                             const char *message)
 {
-    av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n", avctx->frame_number,
-           message);
+    av_log(avctx, AV_LOG_WARNING, "Frame #%d, IFQ: %s\n",
+           avctx->frame_number, message);
 }
 
-AVCodec qcelp_decoder =
+static void postfilter(QCELPContext *q, float *samples, float *lpc)
 {
-    .name   = "qcelp",
-    .type   = CODEC_TYPE_AUDIO,
-    .id     = CODEC_ID_QCELP,
-    .init   = qcelp_decode_init,
-    .decode = qcelp_decode_frame,
+    static const float pow_0_775[10] = {
+        0.775000, 0.600625, 0.465484, 0.360750, 0.279582,
+        0.216676, 0.167924, 0.130141, 0.100859, 0.078166
+    }, pow_0_625[10] = {
+        0.625000, 0.390625, 0.244141, 0.152588, 0.095367,
+        0.059605, 0.037253, 0.023283, 0.014552, 0.009095
+    };
+    float lpc_s[10], lpc_p[10], pole_out[170], zero_out[160];
+    int n;
+
+    for (n = 0; n < 10; n++) {
+        lpc_s[n] = lpc[n] * pow_0_625[n];
+        lpc_p[n] = lpc[n] * pow_0_775[n];
+    }
+
+    ff_celp_lp_zero_synthesis_filterf(zero_out, lpc_s,
+                                      q->formant_mem + 10, 160, 10);
+    memcpy(pole_out, q->postfilter_synth_mem, sizeof(float) * 10);
+    ff_celp_lp_synthesis_filterf(pole_out + 10, lpc_p, zero_out, 160, 10);
+    memcpy(q->postfilter_synth_mem, pole_out + 160, sizeof(float) * 10);
+
+    ff_tilt_compensation(&q->postfilter_tilt_mem, 0.3, pole_out + 10, 160);
+
+    ff_adaptive_gain_control(samples, pole_out + 10,
+                             avpriv_scalarproduct_float_c(q->formant_mem + 10,
+                                                          q->formant_mem + 10,
+                                                          160),
+                             160, 0.9375, &q->postfilter_agc_mem);
+}
+
+static int qcelp_decode_frame(AVCodecContext *avctx, void *data,
+                              int *got_frame_ptr, AVPacket *avpkt)
+{
+    const uint8_t *buf = avpkt->data;
+    int buf_size       = avpkt->size;
+    QCELPContext *q    = avctx->priv_data;
+    AVFrame *frame     = data;
+    float *outbuffer;
+    int   i, ret;
+    float quantized_lspf[10], lpc[10];
+    float gain[16];
+    float *formant_mem;
+
+    /* get output buffer */
+    frame->nb_samples = 160;
+    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
+        return ret;
+    }
+    outbuffer = (float *)frame->data[0];
+
+    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;
+    }
+
+    // postfilter, as per TIA/EIA/IS-733 2.4.8.6
+    postfilter(q, outbuffer, lpc);
+
+    memcpy(q->formant_mem, q->formant_mem + 160, 10 * sizeof(float));
+
+    memcpy(q->prev_lspf, quantized_lspf, sizeof(q->prev_lspf));
+    q->prev_bitrate  = q->bitrate;
+
+    *got_frame_ptr = 1;
+
+    return buf_size;
+}
+
+AVCodec ff_qcelp_decoder = {
+    .name           = "qcelp",
+    .long_name      = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),
+    .type           = AVMEDIA_TYPE_AUDIO,
+    .id             = AV_CODEC_ID_QCELP,
+    .init           = qcelp_decode_init,
+    .decode         = qcelp_decode_frame,
+    .capabilities   = AV_CODEC_CAP_DR1,
     .priv_data_size = sizeof(QCELPContext),
-    .long_name = NULL_IF_CONFIG_SMALL("QCELP / PureVoice"),
 };