static av_cold int imc_decode_init(AVCodecContext * avctx) { int i, j; IMCContext *q = avctx->priv_data; double r1, r2; q->decoder_reset = 1; for(i = 0; i < BANDS; i++) q->old_floor[i] = 1.0; /* Build mdct window, a simple sine window normalized with sqrt(2) */ ff_sine_window_init(q->mdct_sine_window, COEFFS); for(i = 0; i < COEFFS; i++) q->mdct_sine_window[i] *= sqrt(2.0); for(i = 0; i < COEFFS/2; i++){ q->post_cos[i] = (1.0f / 32768) * cos(i / 256.0 * M_PI); q->post_sin[i] = (1.0f / 32768) * sin(i / 256.0 * M_PI); r1 = sin((i * 4.0 + 1.0) / 1024.0 * M_PI); r2 = cos((i * 4.0 + 1.0) / 1024.0 * M_PI); if (i & 0x1) { q->pre_coef1[i] = (r1 + r2) * sqrt(2.0); q->pre_coef2[i] = -(r1 - r2) * sqrt(2.0); } else { q->pre_coef1[i] = -(r1 + r2) * sqrt(2.0); q->pre_coef2[i] = (r1 - r2) * sqrt(2.0); } q->last_fft_im[i] = 0; } /* Generate a square root table */ for(i = 0; i < 30; i++) { q->sqrt_tab[i] = sqrt(i); } /* initialize the VLC tables */ for(i = 0; i < 4 ; i++) { for(j = 0; j < 4; j++) { huffman_vlc[i][j].table = &vlc_tables[vlc_offsets[i * 4 + j]]; huffman_vlc[i][j].table_allocated = vlc_offsets[i * 4 + j + 1] - vlc_offsets[i * 4 + j]; init_vlc(&huffman_vlc[i][j], 9, imc_huffman_sizes[i], imc_huffman_lens[i][j], 1, 1, imc_huffman_bits[i][j], 2, 2, INIT_VLC_USE_NEW_STATIC); } } q->one_div_log2 = 1/log(2); ff_fft_init(&q->fft, 7, 1); dsputil_init(&q->dsp, avctx); avctx->sample_fmt = AV_SAMPLE_FMT_FLT; avctx->channel_layout = (avctx->channels==2) ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO; return 0; }