[FFmpeg-devel] [PATCH] QCELP decoder
Kenan Gillet
kenan.gillet
Mon Nov 10 06:49:20 CET 2008
Hi,
On Nov 8, 2008, at 3:57 PM, Michael Niedermayer wrote:
> On Fri, Nov 07, 2008 at 09:24:25AM -0800, Kenan Gillet wrote:
>> Hi everybody,
>>
>> sorry for the delay,
>>
>> And here is another updated set of patches which makes it round 8.
>> and a small summary:
>
>> - optimizes qcelp_lspf2lpc which is now 60% faster.
>> should it still be in it own file or merging qcelp_lsp.c and
>> qcelpdec.c is
>> ok?
>
> i need to look at this a little more but i think the final code
> should be
> in some file seperate from th qcelpp decoder
>
>
>> - simplifies interpolate_lpc and determine_framerate after Michael
>> comment.
>> - removes useless wrapper function.
>> - added minor version bump in libavcodec/avcodec.h
>> - it fixes the FIR filter to behave like in the reference code
>> - some cosmetics
>>
>
> [...]
>> +typedef struct {
>> + GetBitContext gb;
>> + qcelp_packet_rate framerate;
>> +
>
>> +// beginning of unpacked data
>> + uint8_t cbsign[16];
>> + uint8_t cbgain[16];
>> + uint8_t cindex[16];
>> + uint8_t plag[4];
>> + uint8_t pfrac[4];
>> + uint8_t pgain[4];
>> + uint8_t lspv[10]; /*!< LSP for
>> RATE_OCTAVE, LSPV for other rates */
>> + uint8_t reserved; /*!< on all but rate
>> 1/2 packets */
>> +// end of unpacked data
>
> doxygen has some tags to mark groups of things
> something like ///@{ or so
done
[...]
>> +/**
>> + * Computes the scaled codebook vector Cdn From INDEX and GAIN
>> + * for all rates.
>> + *
>> + * The specification lacks some information here.
>> + *
>> + * TIA/EIA/IS-733 has an omission on the codebook index
>> determination
>> + * formula for RATE_FULL and RATE_HALF frames at section
>> 2.4.8.1.1. It says
>> + * you have to subtract the decoded index parameter from the given
>> scaled
>> + * codebook vector index 'n' to get the desired circular codebook
>> index, but
>> + * it does not mention that you have to clamp 'n' to [0-9] in
>> order to get
>> + * RI-compliant results.
>> + *
>> + * The reason for this mistake seems to be the fact they forgot to
>> mention you
>> + * have to do these calculations per codebook subframe and adjust
>> given
>> + * equation values accordingly.
>> + *
>> + * @param q the context
>> + * @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,
>> + float *gain,
>> + float *cdn_vector) {
>> + int i, j, k;
>> + uint16_t cbseed, cindex;
>> + float *rnd;
>> +
>> + switch (q->framerate) {
>> + case RATE_FULL:
>> + for (i = 0; i < 16; i++) {
>
>> + gain[i] *= QCELP_RATE_FULL_CODEBOOK_RATIO;
>
> it is very hackish to misuse gain as a temporary variable
> gain should be const
done
>> + cindex = -q->cindex[i];
>> + for (j = 0; j < 10; j++)
>> + *cdn_vector++ = gain[i] *
>> qcelp_rate_full_codebook[cindex++ & 127];
>> + }
>> + break;
>> + case RATE_HALF:
>> + for (i = 0; i < 4; i++) {
>> + gain[i] *= QCELP_RATE_HALF_CODEBOOK_RATIO;
>> + cindex = -q->cindex[i];
>> + for (j = 0; j < 40; j++)
>> + *cdn_vector++ = gain[i] *
>> 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->fir_filter_mem + 20;
>> + for (i = 0; i < 8; i++) {
>> + gain[i] *= QCELP_SQRT1887 / 32768.0;
>> + for (k = 0; k < 20; k++) {
>> + cbseed = 521 * cbseed + 259;
>> + *rnd = (int16_t)cbseed;
>> +
>
>> + // FIR filter
>> + *cdn_vector = 0.0;
>> + for (j = 0; j < 10; j++)
>> + *cdn_vector += qcelp_rnd_fir_coefs[j ] * (rnd[-
>> j ] + rnd[-20+j]);
>> + *cdn_vector += qcelp_rnd_fir_coefs[10] *
>> rnd[-10];
>> +
>> + *cdn_vector++ *= gain[i];
>
> i think this would be clearer with a temporary variable insteda of
> using
> *cdn_vector, also it should help gcc in terms of optimization
> simplicity
> as gcc can not exclude that cdn_vector is pointing to gain or another
> array.
done
> [...]
>> +/**
>> + * Apply generic gain control.
>> + *
>> + * @param v_out output vector
>> + * @param v_in vector to control gain of
>> + * @param v_gain gain-controlled vector
>> + *
>> + * TIA/EIA/IS-733 2.4.8.3-2/3/4/5, 2.4.8.6
>> + */
>> +static void apply_gain_ctrl(float *v_out,
>> + const float *v_in,
>> + const float *v_gain) {
>> + int i, j, len;
>> + float scalefactor;
>> +
>> + for (i = 0, j = 0; i < 4; i++) {
>> + scalefactor = ff_dot_productf(v_gain + j, v_gain + j, 40);
>> + if (scalefactor) {
>> + scalefactor = sqrt(ff_dot_productf(v_in + j, v_in + j,
>> 40) / scalefactor);
>> + for (len = j + 40; j < len; j++)
>> + v_out[j] = scalefactor * v_gain[j];
>
> somehow the variable naming seems exchanged
> one would have expected vin->vout and controlled by a vref
done
>> + } else {
>> + memset(v_out + j, 0, 40 * sizeof(float));
>> + j += 40;
>> + }
>> + }
>> +}
>> +
>> +/**
>> * Apply filter in pitch-subframe steps.
>> *
>> * @param memory buffer for the previous state of the filter
>> @@ -90,7 +453,260 @@
>> return memory + 143;
>> }
>>
>> +/**
>> + * Apply pitch synthesis filter and pitch prefilter to the scaled
>> codebook vector.
>> + * TIA/EIA/IS-733 2.4.5.2
>> + *
>> + * @param q the context
>> + * @param cdn_vector the scaled codebook vector
>> + *
>> + * @return 0 on success, -1 if the lag is out of range
>> + */
>> +static int apply_pitch_filters(QCELPContext *q,
>> + float *cdn_vector) {
>> + int i;
>> + float gain[4];
>> + const float *v_synthesis_filtered, *v_pre_filtered;
>> +
>> + if (q->framerate >= RATE_HALF ||
>> + (q->framerate == I_F_Q && (q->prev_framerate >=
>> RATE_HALF))) {
>> +
>> + if (q->framerate >= RATE_HALF) {
>> +
>> + // Compute gain & lag for the whole frame.
>> + for (i = 0; i < 4; i++) {
>> + gain[i] = q->plag[i] ? (q->pgain[i] + 1) / 4.0 :
>> 0.0;
>> +
>> + q->plag[i] += 16;
>> +
>> + if (q->pfrac[i] && q->plag[i] >= 140)
>> + return -1;
>> + }
>> + memcpy(q->prev_pitch_lag, q->plag, 4 * sizeof(*q-
>> >plag));
>> + } else {
>> + gain[3] = q->erasure_count < 3 ? 0.9 - 0.3 * (q-
>> >erasure_count - 1)
>> + : 0.0;
>> + for (i = 0; i < 4; i++)
>> + gain[i] = FFMIN(q->prev_pitch_gain[i], gain[3]);
>> +
>
>> + memset(q->pfrac, 0, 4 *sizeof(*q->pfrac));
>> + memcpy(q->plag, q->prev_pitch_lag, 4 * sizeof(*q-
>> >plag));
>
> s/4*sizeof(*)/ sizeof()/
done
>> + }
>> +
>> + // pitch synthesis filter
>> + v_synthesis_filtered = do_pitchfilter(q-
>> >pitch_synthesis_filter_mem, cdn_vector,
>> + gain, q->plag, q-
>> >pfrac);
>> +
>> + // pitch prefilter update
>> + for (i = 0; i < 4; i++)
>> + gain[i] = 0.5 * FFMIN(gain[i], 1.0);
>> +
>> + v_pre_filtered = do_pitchfilter(q->pitch_pre_filter_mem,
>> v_synthesis_filtered,
>> + gain, q->plag, q->pfrac);
>> +
>> + apply_gain_ctrl(cdn_vector, v_synthesis_filtered,
>> v_pre_filtered);
>> +
>> + memcpy(q->prev_pitch_gain, gain, sizeof(q-
>> >prev_pitch_gain));
>> +
>> + } 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->prev_pitch_gain, 0, sizeof(q->prev_pitch_gain));
>
>> + memset(q->prev_pitch_lag, 0, 4 * sizeof(*q->plag));
>
> same
done
>> + }
>> + return 0;
>> +}
>> +
>
>> +/**
>> + * Interpolates LSP frequencies and computes LPC coefficients
>> + * for a given framerate & pitch subframe.
>> + *
>> + * TIA/EIA/IS-733 2.4.3.3.4
>> + *
>> + * @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) {
>> + float interpolated_lspf[10];
>> + float weight;
>> +
>> + if (q->framerate >= RATE_QUARTER) {
>> + weight = 0.25 * (subframe_num + 1);
>> + } else if (q->framerate == 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);
>
>> + if (q->framerate >= RATE_QUARTER || !subframe_num)
>> + lspf2lpc(q, interpolated_lspf, lpc);
>
> this if is unneeded
done
>> + } else if (q->framerate >= RATE_QUARTER || (q->framerate ==
>> I_F_Q && !subframe_num))
>> + lspf2lpc(q, curr_lspf, lpc);
>> +}
>> +
>
>> +static int buf_size2framerate(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;
>> + }
>> + return -1;
>> +}
>
> ok
>
>
>> +/*
>> + * Determine the framerate from the frame size and/or the first
>> byte of the frame.
>> + *
>> + * @param avctx the AV codec context
>> + * @param q the QCELP context
>> + * @param buf_size length of the buffer
>> + * @param buf the bufffer
>> + *
>> + * @return 0 on success, negative error number otherwise.
>> + */
>> +static int determine_framerate(AVCodecContext *avctx,
>> + QCELPContext *q,
>> + const int buf_size,
>> + uint8_t **buf) {
>> + if ((q->framerate = buf_size2framerate(buf_size)) >= 0) {
>> + if (q->framerate != **buf) {
>> + av_log(avctx, AV_LOG_WARNING, "Claimed framerate and
>> buffer size mismatch.\n");
>> + q->framerate = **buf;
>> + }
>> + (*buf)++;
>> + } else if ((q->framerate = buf_size2framerate(buf_size + 1))
>> >= 0)
>> + av_log(avctx, AV_LOG_WARNING,
>> + "Framerate byte is missing, guessing the framerate
>> from packet size.\n");
>> + else
>> + return -1;
>> +
>> + if (q->framerate == SILENCE) {
>> + // FIXME: the decoder should not handle SILENCE frames as
>> I_F_Q frames
>> + av_log_missing_feature(avctx, "Blank frame", 1);
>> + q->framerate = I_F_Q;
>> + }
>> + return 0;
>> +}
>
> IMHO this should return the "frame rate" instead of setting q-
> >framerate
> behind the curtain.
done
New patch attached which makes it round 9:
- above changes
- the qcelp_g12ga changed back to float because it seems
see other email for benchmark
Kenan
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