From cac4760bf42f1b7ec93860399fbb7b5bff90005f Mon Sep 17 00:00:00 2001 From: Kostya Shishkov Date: Fri, 8 Jun 2012 19:34:46 +0200 Subject: [PATCH] iac: generate codec tables as they are supposed to be Unlike its predecessor, Indeo Audio codec generates tables depending on sampling rate. Previously decoder used pre-generated tables for 22050 Hz which obviously doesn't work with other frequencies. Many thanks to Maxim Poliakovsky for providing all needed information for this. --- libavcodec/imc.c | 68 ++++++++++++++++++++++++++++++++++++++++---- libavcodec/imcdata.h | 19 ------------- 2 files changed, 62 insertions(+), 25 deletions(-) diff --git a/libavcodec/imc.c b/libavcodec/imc.c index 3856f4a851..6df3e581d7 100644 --- a/libavcodec/imc.c +++ b/libavcodec/imc.c @@ -114,6 +114,62 @@ static const int vlc_offsets[17] = { static VLC_TYPE vlc_tables[VLC_TABLES_SIZE][2]; +static inline double freq2bark(double freq) +{ + return 3.5 * atan((freq / 7500.0) * (freq / 7500.0)) + 13.0 * atan(freq * 0.00076); +} + +static av_cold void iac_generate_tabs(IMCContext *q, int sampling_rate) +{ + double freqmin[32], freqmid[32], freqmax[32]; + double scale = sampling_rate / (256.0 * 2.0 * 2.0); + double nyquist_freq = sampling_rate * 0.5; + double freq, bark, prev_bark = 0, tf, tb; + int i, j; + + for (i = 0; i < 32; i++) { + freq = (band_tab[i] + band_tab[i + 1] - 1) * scale; + bark = freq2bark(freq); + + if (i > 0) { + tb = bark - prev_bark; + q->weights1[i - 1] = pow(10.0, -1.0 * tb); + q->weights2[i - 1] = pow(10.0, -2.7 * tb); + } + prev_bark = bark; + + freqmid[i] = freq; + + tf = freq; + while (tf < nyquist_freq) { + tf += 0.5; + tb = freq2bark(tf); + if (tb > bark + 0.5) + break; + } + freqmax[i] = tf; + + tf = freq; + while (tf > 0.0) { + tf -= 0.5; + tb = freq2bark(tf); + if (tb <= bark - 0.5) + break; + } + freqmin[i] = tf; + } + + for (i = 0; i < 32; i++) { + freq = freqmax[i]; + for (j = 31; j > 0 && freq <= freqmid[j]; j--); + q->cyclTab[i] = j + 1; + + freq = freqmin[i]; + for (j = 0; j < 32 && freq >= freqmid[j]; j++); + q->cyclTab2[i] = j - 1; + } +} + static av_cold int imc_decode_init(AVCodecContext *avctx) { int i, j, ret; @@ -173,14 +229,14 @@ static av_cold int imc_decode_init(AVCodecContext *avctx) } q->one_div_log2 = 1 / log(2); - memcpy(q->cyclTab, cyclTab, sizeof(cyclTab)); - memcpy(q->cyclTab2, cyclTab2, sizeof(cyclTab2)); if (avctx->codec_id == CODEC_ID_IAC) { - q->cyclTab[29] = 31; - q->cyclTab2[31] = 28; - memcpy(q->weights1, iac_weights1, sizeof(iac_weights1)); - memcpy(q->weights2, iac_weights2, sizeof(iac_weights2)); + } + + if (avctx->codec_id == CODEC_ID_IAC) { + iac_generate_tabs(q, avctx->sample_rate); } else { + memcpy(q->cyclTab, cyclTab, sizeof(cyclTab)); + memcpy(q->cyclTab2, cyclTab2, sizeof(cyclTab2)); memcpy(q->weights1, imc_weights1, sizeof(imc_weights1)); memcpy(q->weights2, imc_weights2, sizeof(imc_weights2)); } diff --git a/libavcodec/imcdata.h b/libavcodec/imcdata.h index ea9b3747fc..8e99391d61 100644 --- a/libavcodec/imcdata.h +++ b/libavcodec/imcdata.h @@ -44,25 +44,6 @@ static const int8_t cyclTab2[32] = { 12, 13, 14, 15, 16, 17, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29}; -static const float iac_weights1[31] = { - 0.0538585, 0.0576251, 0.0645592, 0.0494032, 0.0428915, 0.0592188, - 0.0604145, 0.0673549, 0.0797351, 0.0972911, 0.119376, 0.144777, - 0.17181, 0.198625, 0.242918, 0.262113, 0.278434, 0.310752, - 0.319978, 0.328482, 0.354631, 0.380212, 0.388783, 0.400428, - 0.43096, 0.462397, 0.479469, 0.499329, 0.534526, 0.568631, - 0.589218 -}; - -static const float iac_weights2[31] = { - 0.000375307, 0.000450455, 0.000612191, 0.000297262, 0.000202956, - 0.000484887, 0.000511777, 0.000686431, 0.00108256, 0.00185267, - 0.00321869, 0.00541861, 0.00860266, 0.012726, 0.0219151, - 0.0269104, 0.0316774, 0.0426107, 0.046113, 0.0494974, - 0.0608692, 0.0734633, 0.0780208, 0.0844921, 0.103034, - 0.124606, 0.137421, 0.153336, 0.184296, 0.217792, - 0.239742 -}; - static const float imc_weights1[31] = { 0.119595, 0.123124, 0.129192, 9.97377e-2, 8.1923e-2, 9.61153e-2, 8.77885e-2, 8.61174e-2, 9.00882e-2, 9.91658e-2, 0.112991, 0.131126, 0.152886, 0.177292, 0.221782, 0.244917, 0.267386,