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More OKed parts of the QCELP decoder
patch by Kenan Gillet, kenan.gillet gmail com Originally committed as revision 15822 to svn://svn.ffmpeg.org/ffmpeg/trunk
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@ -460,6 +460,15 @@ static const int8_t qcelp_rate_half_codebook[128] = {
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};
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#define QCELP_RATE_HALF_CODEBOOK_RATIO 0.5
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/**
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* sqrt(1.887) is the maximum of the pseudorandom
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* white sequence used to generate the scaled codebook
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* vector for framerate 1/4.
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*
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* TIA/EIA/IS-733 2.4.8.1.2
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*/
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#define QCELP_SQRT1887 1.373681186
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/**
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* table for impulse response of BPF used to filter
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* the white excitation for framerate 1/4 synthesis
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@ -51,6 +51,144 @@ static void weighted_vector_sumf(float *out,
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+ weight_coeff_b * in_b[i];
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}
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/**
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* Initialize the speech codec according to the specification.
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*
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* TIA/EIA/IS-733 2.4.9
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*/
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static av_cold int qcelp_decode_init(AVCodecContext *avctx) {
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QCELPContext *q = avctx->priv_data;
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int i;
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avctx->sample_fmt = SAMPLE_FMT_FLT;
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for (i = 0; i < 10; i++)
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q->prev_lspf[i] = (i + 1) / 11.;
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return 0;
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}
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/**
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* Computes the scaled codebook vector Cdn From INDEX and GAIN
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* for all rates.
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*
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* The specification lacks some information here.
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*
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* TIA/EIA/IS-733 has an omission on the codebook index determination
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* formula for RATE_FULL and RATE_HALF frames at section 2.4.8.1.1. It says
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* you have to subtract the decoded index parameter from the given scaled
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* codebook vector index 'n' to get the desired circular codebook index, but
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* it does not mention that you have to clamp 'n' to [0-9] in order to get
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* RI-compliant results.
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*
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* The reason for this mistake seems to be the fact they forgot to mention you
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* have to do these calculations per codebook subframe and adjust given
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* equation values accordingly.
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*
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* @param q the context
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* @param gain array holding the 4 pitch subframe gain values
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* @param cdn_vector array for the generated scaled codebook vector
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*/
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static void compute_svector(const QCELPContext *q,
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const float *gain,
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float *cdn_vector) {
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int i, j, k;
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uint16_t cbseed, cindex;
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float *rnd, tmp_gain, fir_filter_value;
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switch (q->framerate) {
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case RATE_FULL:
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for (i = 0; i < 16; i++) {
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tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
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cindex = -q->cindex[i];
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for (j = 0; j < 10; j++)
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*cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cindex++ & 127];
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}
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break;
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case RATE_HALF:
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for (i = 0; i < 4; i++) {
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tmp_gain = gain[i] * QCELP_RATE_HALF_CODEBOOK_RATIO;
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cindex = -q->cindex[i];
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for (j = 0; j < 40; j++)
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*cdn_vector++ = tmp_gain * qcelp_rate_half_codebook[cindex++ & 127];
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}
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break;
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case RATE_QUARTER:
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cbseed = (0x0003 & q->lspv[4])<<14 |
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(0x003F & q->lspv[3])<< 8 |
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(0x0060 & q->lspv[2])<< 1 |
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(0x0007 & q->lspv[1])<< 3 |
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(0x0038 & q->lspv[0])>> 3 ;
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rnd = q->rnd_fir_filter_mem + 20;
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for (i = 0; i < 8; i++) {
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tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
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for (k = 0; k < 20; k++) {
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cbseed = 521 * cbseed + 259;
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*rnd = (int16_t)cbseed;
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// FIR filter
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fir_filter_value = 0.0;
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for (j = 0; j < 10; j++)
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fir_filter_value += qcelp_rnd_fir_coefs[j ] * (rnd[-j ] + rnd[-20+j]);
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fir_filter_value += qcelp_rnd_fir_coefs[10] * rnd[-10];
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*cdn_vector++ = tmp_gain * fir_filter_value;
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rnd++;
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}
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}
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memcpy(q->rnd_fir_filter_mem, q->rnd_fir_filter_mem + 160, 20 * sizeof(float));
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break;
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case RATE_OCTAVE:
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cbseed = q->first16bits;
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for (i = 0; i < 8; i++) {
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tmp_gain = gain[i] * (QCELP_SQRT1887 / 32768.0);
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for (j = 0; j < 20; j++) {
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cbseed = 521 * cbseed + 259;
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*cdn_vector++ = tmp_gain * (int16_t)cbseed;
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}
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}
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break;
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case I_F_Q:
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cbseed = -44; // random codebook index
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for (i = 0; i < 4; i++) {
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tmp_gain = gain[i] * QCELP_RATE_FULL_CODEBOOK_RATIO;
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for (j = 0; j < 40; j++)
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*cdn_vector++ = tmp_gain * qcelp_rate_full_codebook[cbseed++ & 127];
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}
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break;
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}
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}
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/**
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* Apply generic gain control.
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*
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* @param v_out output vector
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* @param v_in gain-controlled vector
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* @param v_ref vector to control gain of
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*
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* FIXME: If v_ref is a zero vector, it energy is zero
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* and the behavior of the gain control is
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* undefined in the specs.
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*
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* TIA/EIA/IS-733 2.4.8.3-2/3/4/5, 2.4.8.6
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*/
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static void apply_gain_ctrl(float *v_out,
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const float *v_ref,
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const float *v_in) {
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int i, j, len;
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float scalefactor;
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for (i = 0, j = 0; i < 4; i++) {
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scalefactor = ff_dot_productf(v_in + j, v_in + j, 40);
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if (scalefactor)
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scalefactor = sqrt(ff_dot_productf(v_ref + j, v_ref + j, 40) / scalefactor);
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else
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av_log_missing_feature(NULL, "Zero energy for gain control", 1);
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for (len = j + 40; j < len; j++)
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v_out[j] = scalefactor * v_in[j];
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}
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}
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/**
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* Apply filter in pitch-subframe steps.
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*
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@ -131,9 +269,9 @@ void interpolate_lpc(QCELPContext *q,
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if (weight != 1.0) {
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weighted_vector_sumf(interpolated_lspf, curr_lspf, q->prev_lspf, weight, 1.0 - weight, 10);
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lspf2lpc(q, interpolated_lspf, lpc);
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qcelp_lspf2lpc(interpolated_lspf, lpc);
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} else if (q->framerate >= RATE_QUARTER || (q->framerate == I_F_Q && !subframe_num))
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lspf2lpc(q, curr_lspf, lpc);
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qcelp_lspf2lpc(curr_lspf, lpc);
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}
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static int buf_size2framerate(const int buf_size) {
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