2 * IMC compatible decoder
3 * Copyright (c) 2002-2004 Maxim Poliakovski
4 * Copyright (c) 2006 Benjamin Larsson
5 * Copyright (c) 2006 Konstantin Shishkov
7 * This file is part of FFmpeg.
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 * IMC - Intel Music Coder
27 * A mdct based codec using a 256 points large transform
28 * divided into 32 bands with some mix of scale factors.
29 * Only mono is supported.
42 #include "libavutil/audioconvert.h"
47 #define IMC_BLOCK_SIZE 64
48 #define IMC_FRAME_ID 0x21
55 float old_floor[BANDS];
56 float flcoeffs1[BANDS];
57 float flcoeffs2[BANDS];
58 float flcoeffs3[BANDS];
59 float flcoeffs4[BANDS];
60 float flcoeffs5[BANDS];
61 float flcoeffs6[BANDS];
62 float CWdecoded[COEFFS];
66 float mdct_sine_window[COEFFS];
67 float post_cos[COEFFS];
68 float post_sin[COEFFS];
69 float pre_coef1[COEFFS];
70 float pre_coef2[COEFFS];
71 float last_fft_im[COEFFS];
74 int bandWidthT[BANDS]; ///< codewords per band
75 int bitsBandT[BANDS]; ///< how many bits per codeword in band
76 int CWlengthT[COEFFS]; ///< how many bits in each codeword
77 int levlCoeffBuf[BANDS];
78 int bandFlagsBuf[BANDS]; ///< flags for each band
79 int sumLenArr[BANDS]; ///< bits for all coeffs in band
80 int skipFlagRaw[BANDS]; ///< skip flags are stored in raw form or not
81 int skipFlagBits[BANDS]; ///< bits used to code skip flags
82 int skipFlagCount[BANDS]; ///< skipped coeffients per band
83 int skipFlags[COEFFS]; ///< skip coefficient decoding or not
84 int codewords[COEFFS]; ///< raw codewords read from bitstream
92 DECLARE_ALIGNED(32, FFTComplex, samples)[COEFFS / 2];
96 static VLC huffman_vlc[4][4];
98 #define VLC_TABLES_SIZE 9512
100 static const int vlc_offsets[17] = {
101 0, 640, 1156, 1732, 2308, 2852, 3396, 3924,
102 4452, 5220, 5860, 6628, 7268, 7908, 8424, 8936, VLC_TABLES_SIZE
105 static VLC_TYPE vlc_tables[VLC_TABLES_SIZE][2];
107 static av_cold int imc_decode_init(AVCodecContext *avctx)
110 IMCContext *q = avctx->priv_data;
113 if (avctx->channels != 1) {
114 av_log_ask_for_sample(avctx, "Number of channels is not supported\n");
115 return AVERROR_PATCHWELCOME;
118 q->decoder_reset = 1;
120 for (i = 0; i < BANDS; i++)
121 q->old_floor[i] = 1.0;
123 /* Build mdct window, a simple sine window normalized with sqrt(2) */
124 ff_sine_window_init(q->mdct_sine_window, COEFFS);
125 for (i = 0; i < COEFFS; i++)
126 q->mdct_sine_window[i] *= sqrt(2.0);
127 for (i = 0; i < COEFFS / 2; i++) {
128 q->post_cos[i] = (1.0f / 32768) * cos(i / 256.0 * M_PI);
129 q->post_sin[i] = (1.0f / 32768) * sin(i / 256.0 * M_PI);
131 r1 = sin((i * 4.0 + 1.0) / 1024.0 * M_PI);
132 r2 = cos((i * 4.0 + 1.0) / 1024.0 * M_PI);
135 q->pre_coef1[i] = (r1 + r2) * sqrt(2.0);
136 q->pre_coef2[i] = -(r1 - r2) * sqrt(2.0);
138 q->pre_coef1[i] = -(r1 + r2) * sqrt(2.0);
139 q->pre_coef2[i] = (r1 - r2) * sqrt(2.0);
142 q->last_fft_im[i] = 0;
145 /* Generate a square root table */
147 for (i = 0; i < 30; i++)
148 q->sqrt_tab[i] = sqrt(i);
150 /* initialize the VLC tables */
151 for (i = 0; i < 4 ; i++) {
152 for (j = 0; j < 4; j++) {
153 huffman_vlc[i][j].table = &vlc_tables[vlc_offsets[i * 4 + j]];
154 huffman_vlc[i][j].table_allocated = vlc_offsets[i * 4 + j + 1] - vlc_offsets[i * 4 + j];
155 init_vlc(&huffman_vlc[i][j], 9, imc_huffman_sizes[i],
156 imc_huffman_lens[i][j], 1, 1,
157 imc_huffman_bits[i][j], 2, 2, INIT_VLC_USE_NEW_STATIC);
160 q->one_div_log2 = 1 / log(2);
162 if ((ret = ff_fft_init(&q->fft, 7, 1))) {
163 av_log(avctx, AV_LOG_INFO, "FFT init failed\n");
166 ff_dsputil_init(&q->dsp, avctx);
167 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
168 avctx->channel_layout = AV_CH_LAYOUT_MONO;
170 avcodec_get_frame_defaults(&q->frame);
171 avctx->coded_frame = &q->frame;
176 static void imc_calculate_coeffs(IMCContext *q, float *flcoeffs1,
177 float *flcoeffs2, int *bandWidthT,
178 float *flcoeffs3, float *flcoeffs5)
183 float snr_limit = 1.e-30;
187 for (i = 0; i < BANDS; i++) {
188 flcoeffs5[i] = workT2[i] = 0.0;
190 workT1[i] = flcoeffs1[i] * flcoeffs1[i];
191 flcoeffs3[i] = 2.0 * flcoeffs2[i];
194 flcoeffs3[i] = -30000.0;
196 workT3[i] = bandWidthT[i] * workT1[i] * 0.01;
197 if (workT3[i] <= snr_limit)
201 for (i = 0; i < BANDS; i++) {
202 for (cnt2 = i; cnt2 < cyclTab[i]; cnt2++)
203 flcoeffs5[cnt2] = flcoeffs5[cnt2] + workT3[i];
204 workT2[cnt2 - 1] = workT2[cnt2 - 1] + workT3[i];
207 for (i = 1; i < BANDS; i++) {
208 accum = (workT2[i - 1] + accum) * imc_weights1[i - 1];
209 flcoeffs5[i] += accum;
212 for (i = 0; i < BANDS; i++)
215 for (i = 0; i < BANDS; i++) {
216 for (cnt2 = i - 1; cnt2 > cyclTab2[i]; cnt2--)
217 flcoeffs5[cnt2] += workT3[i];
218 workT2[cnt2+1] += workT3[i];
223 for (i = BANDS-2; i >= 0; i--) {
224 accum = (workT2[i+1] + accum) * imc_weights2[i];
225 flcoeffs5[i] += accum;
226 // there is missing code here, but it seems to never be triggered
231 static void imc_read_level_coeffs(IMCContext *q, int stream_format_code,
237 const uint8_t *cb_sel;
240 s = stream_format_code >> 1;
241 hufftab[0] = &huffman_vlc[s][0];
242 hufftab[1] = &huffman_vlc[s][1];
243 hufftab[2] = &huffman_vlc[s][2];
244 hufftab[3] = &huffman_vlc[s][3];
245 cb_sel = imc_cb_select[s];
247 if (stream_format_code & 4)
250 levlCoeffs[0] = get_bits(&q->gb, 7);
251 for (i = start; i < BANDS; i++) {
252 levlCoeffs[i] = get_vlc2(&q->gb, hufftab[cb_sel[i]]->table,
253 hufftab[cb_sel[i]]->bits, 2);
254 if (levlCoeffs[i] == 17)
255 levlCoeffs[i] += get_bits(&q->gb, 4);
259 static void imc_decode_level_coefficients(IMCContext *q, int *levlCoeffBuf,
260 float *flcoeffs1, float *flcoeffs2)
264 // maybe some frequency division thingy
266 flcoeffs1[0] = 20000.0 / pow (2, levlCoeffBuf[0] * 0.18945); // 0.18945 = log2(10) * 0.05703125
267 flcoeffs2[0] = log(flcoeffs1[0]) / log(2);
271 for (i = 1; i < BANDS; i++) {
272 level = levlCoeffBuf[i];
279 else if (level <= 24)
284 tmp *= imc_exp_tab[15 + level];
285 tmp2 += 0.83048 * level; // 0.83048 = log2(10) * 0.25
293 static void imc_decode_level_coefficients2(IMCContext *q, int *levlCoeffBuf,
294 float *old_floor, float *flcoeffs1,
298 /* FIXME maybe flag_buf = noise coding and flcoeffs1 = new scale factors
299 * and flcoeffs2 old scale factors
300 * might be incomplete due to a missing table that is in the binary code
302 for (i = 0; i < BANDS; i++) {
304 if (levlCoeffBuf[i] < 16) {
305 flcoeffs1[i] = imc_exp_tab2[levlCoeffBuf[i]] * old_floor[i];
306 flcoeffs2[i] = (levlCoeffBuf[i] - 7) * 0.83048 + flcoeffs2[i]; // 0.83048 = log2(10) * 0.25
308 flcoeffs1[i] = old_floor[i];
314 * Perform bit allocation depending on bits available
316 static int bit_allocation(IMCContext *q, int stream_format_code, int freebits,
320 const float limit = -1.e20;
329 float lowest = 1.e10;
335 for (i = 0; i < BANDS; i++)
336 highest = FFMAX(highest, q->flcoeffs1[i]);
338 for (i = 0; i < BANDS - 1; i++)
339 q->flcoeffs4[i] = q->flcoeffs3[i] - log(q->flcoeffs5[i]) / log(2);
340 q->flcoeffs4[BANDS - 1] = limit;
342 highest = highest * 0.25;
344 for (i = 0; i < BANDS; i++) {
346 if ((band_tab[i + 1] - band_tab[i]) == q->bandWidthT[i])
349 if ((band_tab[i + 1] - band_tab[i]) > q->bandWidthT[i])
352 if (((band_tab[i + 1] - band_tab[i]) / 2) >= q->bandWidthT[i])
356 return AVERROR_INVALIDDATA;
358 q->flcoeffs4[i] += xTab[(indx * 2 + (q->flcoeffs1[i] < highest)) * 2 + flag];
361 if (stream_format_code & 0x2) {
362 q->flcoeffs4[0] = limit;
363 q->flcoeffs4[1] = limit;
364 q->flcoeffs4[2] = limit;
365 q->flcoeffs4[3] = limit;
368 for (i = (stream_format_code & 0x2) ? 4 : 0; i < BANDS - 1; i++) {
369 iacc += q->bandWidthT[i];
370 summa += q->bandWidthT[i] * q->flcoeffs4[i];
372 q->bandWidthT[BANDS - 1] = 0;
373 summa = (summa * 0.5 - freebits) / iacc;
376 for (i = 0; i < BANDS / 2; i++) {
377 rres = summer - freebits;
378 if ((rres >= -8) && (rres <= 8))
384 for (j = (stream_format_code & 0x2) ? 4 : 0; j < BANDS; j++) {
385 cwlen = av_clipf(((q->flcoeffs4[j] * 0.5) - summa + 0.5), 0, 6);
387 q->bitsBandT[j] = cwlen;
388 summer += q->bandWidthT[j] * cwlen;
391 iacc += q->bandWidthT[j];
396 if (freebits < summer)
403 summa = (float)(summer - freebits) / ((t1 + 1) * iacc) + summa;
406 for (i = (stream_format_code & 0x2) ? 4 : 0; i < BANDS; i++) {
407 for (j = band_tab[i]; j < band_tab[i + 1]; j++)
408 q->CWlengthT[j] = q->bitsBandT[i];
411 if (freebits > summer) {
412 for (i = 0; i < BANDS; i++) {
413 workT[i] = (q->bitsBandT[i] == 6) ? -1.e20
414 : (q->bitsBandT[i] * -2 + q->flcoeffs4[i] - 0.415);
420 if (highest <= -1.e20)
426 for (i = 0; i < BANDS; i++) {
427 if (workT[i] > highest) {
433 if (highest > -1.e20) {
434 workT[found_indx] -= 2.0;
435 if (++q->bitsBandT[found_indx] == 6)
436 workT[found_indx] = -1.e20;
438 for (j = band_tab[found_indx]; j < band_tab[found_indx + 1] && (freebits > summer); j++) {
443 } while (freebits > summer);
445 if (freebits < summer) {
446 for (i = 0; i < BANDS; i++) {
447 workT[i] = q->bitsBandT[i] ? (q->bitsBandT[i] * -2 + q->flcoeffs4[i] + 1.585)
450 if (stream_format_code & 0x2) {
456 while (freebits < summer) {
459 for (i = 0; i < BANDS; i++) {
460 if (workT[i] < lowest) {
465 // if (lowest >= 1.e10)
467 workT[low_indx] = lowest + 2.0;
469 if (!--q->bitsBandT[low_indx])
470 workT[low_indx] = 1.e20;
472 for (j = band_tab[low_indx]; j < band_tab[low_indx+1] && (freebits < summer); j++) {
473 if (q->CWlengthT[j] > 0) {
483 static void imc_get_skip_coeff(IMCContext *q)
487 memset(q->skipFlagBits, 0, sizeof(q->skipFlagBits));
488 memset(q->skipFlagCount, 0, sizeof(q->skipFlagCount));
489 for (i = 0; i < BANDS; i++) {
490 if (!q->bandFlagsBuf[i] || !q->bandWidthT[i])
493 if (!q->skipFlagRaw[i]) {
494 q->skipFlagBits[i] = band_tab[i + 1] - band_tab[i];
496 for (j = band_tab[i]; j < band_tab[i + 1]; j++) {
497 q->skipFlags[j] = get_bits1(&q->gb);
499 q->skipFlagCount[i]++;
502 for (j = band_tab[i]; j < band_tab[i + 1] - 1; j += 2) {
503 if (!get_bits1(&q->gb)) { // 0
504 q->skipFlagBits[i]++;
506 q->skipFlags[j + 1] = 1;
507 q->skipFlagCount[i] += 2;
509 if (get_bits1(&q->gb)) { // 11
510 q->skipFlagBits[i] += 2;
512 q->skipFlags[j + 1] = 1;
513 q->skipFlagCount[i]++;
515 q->skipFlagBits[i] += 3;
516 q->skipFlags[j + 1] = 0;
517 if (!get_bits1(&q->gb)) { // 100
519 q->skipFlagCount[i]++;
527 if (j < band_tab[i + 1]) {
528 q->skipFlagBits[i]++;
529 if ((q->skipFlags[j] = get_bits1(&q->gb)))
530 q->skipFlagCount[i]++;
537 * Increase highest' band coefficient sizes as some bits won't be used
539 static void imc_adjust_bit_allocation(IMCContext *q, int summer)
547 for (i = 0; i < BANDS; i++) {
548 workT[i] = (q->bitsBandT[i] == 6) ? -1.e20
549 : (q->bitsBandT[i] * -2 + q->flcoeffs4[i] - 0.415);
552 while (corrected < summer) {
553 if (highest <= -1.e20)
558 for (i = 0; i < BANDS; i++) {
559 if (workT[i] > highest) {
565 if (highest > -1.e20) {
566 workT[found_indx] -= 2.0;
567 if (++(q->bitsBandT[found_indx]) == 6)
568 workT[found_indx] = -1.e20;
570 for (j = band_tab[found_indx]; j < band_tab[found_indx+1] && (corrected < summer); j++) {
571 if (!q->skipFlags[j] && (q->CWlengthT[j] < 6)) {
580 static void imc_imdct256(IMCContext *q)
586 for (i = 0; i < COEFFS / 2; i++) {
587 q->samples[i].re = -(q->pre_coef1[i] * q->CWdecoded[COEFFS - 1 - i * 2]) -
588 (q->pre_coef2[i] * q->CWdecoded[i * 2]);
589 q->samples[i].im = (q->pre_coef2[i] * q->CWdecoded[COEFFS - 1 - i * 2]) -
590 (q->pre_coef1[i] * q->CWdecoded[i * 2]);
594 q->fft.fft_permute(&q->fft, q->samples);
595 q->fft.fft_calc(&q->fft, q->samples);
597 /* postrotation, window and reorder */
598 for (i = 0; i < COEFFS / 2; i++) {
599 re = ( q->samples[i].re * q->post_cos[i]) + (-q->samples[i].im * q->post_sin[i]);
600 im = (-q->samples[i].im * q->post_cos[i]) - ( q->samples[i].re * q->post_sin[i]);
601 q->out_samples[i * 2] = (q->mdct_sine_window[COEFFS - 1 - i * 2] * q->last_fft_im[i])
602 + (q->mdct_sine_window[i * 2] * re);
603 q->out_samples[COEFFS - 1 - i * 2] = (q->mdct_sine_window[i * 2] * q->last_fft_im[i])
604 - (q->mdct_sine_window[COEFFS - 1 - i * 2] * re);
605 q->last_fft_im[i] = im;
609 static int inverse_quant_coeff(IMCContext *q, int stream_format_code)
612 int middle_value, cw_len, max_size;
613 const float *quantizer;
615 for (i = 0; i < BANDS; i++) {
616 for (j = band_tab[i]; j < band_tab[i + 1]; j++) {
618 cw_len = q->CWlengthT[j];
620 if (cw_len <= 0 || q->skipFlags[j])
623 max_size = 1 << cw_len;
624 middle_value = max_size >> 1;
626 if (q->codewords[j] >= max_size || q->codewords[j] < 0)
627 return AVERROR_INVALIDDATA;
630 quantizer = imc_quantizer2[(stream_format_code & 2) >> 1];
631 if (q->codewords[j] >= middle_value)
632 q->CWdecoded[j] = quantizer[q->codewords[j] - 8] * q->flcoeffs6[i];
634 q->CWdecoded[j] = -quantizer[max_size - q->codewords[j] - 8 - 1] * q->flcoeffs6[i];
636 quantizer = imc_quantizer1[((stream_format_code & 2) >> 1) | (q->bandFlagsBuf[i] << 1)];
637 if (q->codewords[j] >= middle_value)
638 q->CWdecoded[j] = quantizer[q->codewords[j] - 1] * q->flcoeffs6[i];
640 q->CWdecoded[j] = -quantizer[max_size - 2 - q->codewords[j]] * q->flcoeffs6[i];
648 static int imc_get_coeffs(IMCContext *q)
650 int i, j, cw_len, cw;
652 for (i = 0; i < BANDS; i++) {
653 if (!q->sumLenArr[i])
655 if (q->bandFlagsBuf[i] || q->bandWidthT[i]) {
656 for (j = band_tab[i]; j < band_tab[i + 1]; j++) {
657 cw_len = q->CWlengthT[j];
660 if (get_bits_count(&q->gb) + cw_len > 512) {
661 // av_log(NULL, 0, "Band %i coeff %i cw_len %i\n", i, j, cw_len);
662 return AVERROR_INVALIDDATA;
665 if (cw_len && (!q->bandFlagsBuf[i] || !q->skipFlags[j]))
666 cw = get_bits(&q->gb, cw_len);
668 q->codewords[j] = cw;
675 static int imc_decode_frame(AVCodecContext *avctx, void *data,
676 int *got_frame_ptr, AVPacket *avpkt)
678 const uint8_t *buf = avpkt->data;
679 int buf_size = avpkt->size;
681 IMCContext *q = avctx->priv_data;
683 int stream_format_code;
684 int imc_hdr, i, j, ret;
687 int counter, bitscount;
688 LOCAL_ALIGNED_16(uint16_t, buf16, [IMC_BLOCK_SIZE / 2]);
690 if (buf_size < IMC_BLOCK_SIZE) {
691 av_log(avctx, AV_LOG_ERROR, "imc frame too small!\n");
692 return AVERROR_INVALIDDATA;
695 /* get output buffer */
696 q->frame.nb_samples = COEFFS;
697 if ((ret = avctx->get_buffer(avctx, &q->frame)) < 0) {
698 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
701 q->out_samples = (float*)q->frame.data[0];
703 q->dsp.bswap16_buf(buf16, (const uint16_t*)buf, IMC_BLOCK_SIZE / 2);
705 init_get_bits(&q->gb, (const uint8_t*)buf16, IMC_BLOCK_SIZE * 8);
707 /* Check the frame header */
708 imc_hdr = get_bits(&q->gb, 9);
709 if (imc_hdr != IMC_FRAME_ID) {
710 av_log(avctx, AV_LOG_ERROR, "imc frame header check failed!\n");
711 av_log(avctx, AV_LOG_ERROR, "got %x instead of 0x21.\n", imc_hdr);
712 return AVERROR_INVALIDDATA;
714 stream_format_code = get_bits(&q->gb, 3);
716 if (stream_format_code & 1) {
717 av_log(avctx, AV_LOG_ERROR, "Stream code format %X is not supported\n", stream_format_code);
718 return AVERROR_INVALIDDATA;
721 // av_log(avctx, AV_LOG_DEBUG, "stream_format_code = %d\n", stream_format_code);
723 if (stream_format_code & 0x04)
724 q->decoder_reset = 1;
726 if (q->decoder_reset) {
727 memset(q->out_samples, 0, sizeof(q->out_samples));
728 for (i = 0; i < BANDS; i++)
729 q->old_floor[i] = 1.0;
730 for (i = 0; i < COEFFS; i++)
732 q->decoder_reset = 0;
735 flag = get_bits1(&q->gb);
736 imc_read_level_coeffs(q, stream_format_code, q->levlCoeffBuf);
738 if (stream_format_code & 0x4)
739 imc_decode_level_coefficients(q, q->levlCoeffBuf,
740 q->flcoeffs1, q->flcoeffs2);
742 imc_decode_level_coefficients2(q, q->levlCoeffBuf, q->old_floor,
743 q->flcoeffs1, q->flcoeffs2);
745 memcpy(q->old_floor, q->flcoeffs1, 32 * sizeof(float));
748 for (i = 0; i < BANDS; i++) {
749 if (q->levlCoeffBuf[i] == 16) {
750 q->bandWidthT[i] = 0;
753 q->bandWidthT[i] = band_tab[i + 1] - band_tab[i];
755 memset(q->bandFlagsBuf, 0, BANDS * sizeof(int));
756 for (i = 0; i < BANDS - 1; i++) {
757 if (q->bandWidthT[i])
758 q->bandFlagsBuf[i] = get_bits1(&q->gb);
761 imc_calculate_coeffs(q, q->flcoeffs1, q->flcoeffs2, q->bandWidthT, q->flcoeffs3, q->flcoeffs5);
764 /* first 4 bands will be assigned 5 bits per coefficient */
765 if (stream_format_code & 0x2) {
772 for (i = 1; i < 4; i++) {
773 bits = (q->levlCoeffBuf[i] == 16) ? 0 : 5;
774 q->bitsBandT[i] = bits;
775 for (j = band_tab[i]; j < band_tab[i + 1]; j++) {
776 q->CWlengthT[j] = bits;
782 if ((ret = bit_allocation(q, stream_format_code,
783 512 - bitscount - get_bits_count(&q->gb),
785 av_log(avctx, AV_LOG_ERROR, "Bit allocations failed\n");
786 q->decoder_reset = 1;
790 for (i = 0; i < BANDS; i++) {
792 q->skipFlagRaw[i] = 0;
793 for (j = band_tab[i]; j < band_tab[i + 1]; j++)
794 q->sumLenArr[i] += q->CWlengthT[j];
795 if (q->bandFlagsBuf[i])
796 if ((((band_tab[i + 1] - band_tab[i]) * 1.5) > q->sumLenArr[i]) && (q->sumLenArr[i] > 0))
797 q->skipFlagRaw[i] = 1;
800 imc_get_skip_coeff(q);
802 for (i = 0; i < BANDS; i++) {
803 q->flcoeffs6[i] = q->flcoeffs1[i];
804 /* band has flag set and at least one coded coefficient */
805 if (q->bandFlagsBuf[i] && (band_tab[i + 1] - band_tab[i]) != q->skipFlagCount[i]) {
806 q->flcoeffs6[i] *= q->sqrt_tab[ band_tab[i + 1] - band_tab[i]] /
807 q->sqrt_tab[(band_tab[i + 1] - band_tab[i] - q->skipFlagCount[i])];
811 /* calculate bits left, bits needed and adjust bit allocation */
814 for (i = 0; i < BANDS; i++) {
815 if (q->bandFlagsBuf[i]) {
816 for (j = band_tab[i]; j < band_tab[i + 1]; j++) {
817 if (q->skipFlags[j]) {
818 summer += q->CWlengthT[j];
822 bits += q->skipFlagBits[i];
823 summer -= q->skipFlagBits[i];
826 imc_adjust_bit_allocation(q, summer);
828 for (i = 0; i < BANDS; i++) {
831 for (j = band_tab[i]; j < band_tab[i + 1]; j++)
832 if (!q->skipFlags[j])
833 q->sumLenArr[i] += q->CWlengthT[j];
836 memset(q->codewords, 0, sizeof(q->codewords));
838 if (imc_get_coeffs(q) < 0) {
839 av_log(avctx, AV_LOG_ERROR, "Read coefficients failed\n");
840 q->decoder_reset = 1;
841 return AVERROR_INVALIDDATA;
844 if (inverse_quant_coeff(q, stream_format_code) < 0) {
845 av_log(avctx, AV_LOG_ERROR, "Inverse quantization of coefficients failed\n");
846 q->decoder_reset = 1;
847 return AVERROR_INVALIDDATA;
850 memset(q->skipFlags, 0, sizeof(q->skipFlags));
855 *(AVFrame *)data = q->frame;
857 return IMC_BLOCK_SIZE;
861 static av_cold int imc_decode_close(AVCodecContext * avctx)
863 IMCContext *q = avctx->priv_data;
871 AVCodec ff_imc_decoder = {
873 .type = AVMEDIA_TYPE_AUDIO,
875 .priv_data_size = sizeof(IMCContext),
876 .init = imc_decode_init,
877 .close = imc_decode_close,
878 .decode = imc_decode_frame,
879 .capabilities = CODEC_CAP_DR1,
880 .long_name = NULL_IF_CONFIG_SMALL("IMC (Intel Music Coder)"),