commit more OKed parts of the E-AC-3 decoder
Originally committed as revision 15067 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles
parent
86e456f63e
commit
d82bdf684b
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@ -78,3 +78,414 @@ static void idct6(int pre_mant[6])
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pre_mant[4] = even1 - odd1;
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pre_mant[5] = even0 - odd0;
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}
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void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch)
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{
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int bin, blk, gs;
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int end_bap, gaq_mode;
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GetBitContext *gbc = &s->gbc;
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int gaq_gain[AC3_MAX_COEFS];
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gaq_mode = get_bits(gbc, 2);
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end_bap = (gaq_mode < 2) ? 12 : 17;
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/* if GAQ gain is used, decode gain codes for bins with hebap between
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8 and end_bap */
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gs = 0;
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if (gaq_mode == EAC3_GAQ_12 || gaq_mode == EAC3_GAQ_14) {
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/* read 1-bit GAQ gain codes */
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for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
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if (s->bap[ch][bin] > 7 && s->bap[ch][bin] < end_bap)
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gaq_gain[gs++] = get_bits1(gbc) << (gaq_mode-1);
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}
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} else if (gaq_mode == EAC3_GAQ_124) {
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/* read 1.67-bit GAQ gain codes (3 codes in 5 bits) */
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int gc = 2;
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for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
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if (s->bap[ch][bin] > 7 && s->bap[ch][bin] < 17) {
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if (gc++ == 2) {
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int group_code = get_bits(gbc, 5);
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if (group_code > 26) {
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av_log(s->avctx, AV_LOG_WARNING, "GAQ gain group code out-of-range\n");
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group_code = 26;
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}
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gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][0];
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gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][1];
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gaq_gain[gs++] = ff_ac3_ungroup_3_in_5_bits_tab[group_code][2];
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gc = 0;
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}
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}
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}
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}
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gs=0;
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for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
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int hebap = s->bap[ch][bin];
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int bits = ff_eac3_bits_vs_hebap[hebap];
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if (!hebap) {
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/* zero-mantissa dithering */
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for (blk = 0; blk < 6; blk++) {
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s->pre_mantissa[ch][bin][blk] = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
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}
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} else if (hebap < 8) {
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/* Vector Quantization */
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int v = get_bits(gbc, bits);
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for (blk = 0; blk < 6; blk++) {
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s->pre_mantissa[ch][bin][blk] = ff_eac3_vq_hebap[hebap][v][blk] << 8;
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}
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} else {
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/* Gain Adaptive Quantization */
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int gbits, log_gain;
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if (gaq_mode != EAC3_GAQ_NO && hebap < end_bap) {
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log_gain = gaq_gain[gs++];
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} else {
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log_gain = 0;
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}
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gbits = bits - log_gain;
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for (blk = 0; blk < 6; blk++) {
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int mant = get_sbits(gbc, gbits);
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if (mant == -(1 << (gbits-1))) {
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/* large mantissa */
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int b;
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mant = get_sbits(gbc, bits-2+log_gain) << (26-log_gain-bits);
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/* remap mantissa value to correct for asymmetric quantization */
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if (mant >= 0)
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b = 32768 >> (log_gain+8);
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else
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b = ff_eac3_gaq_remap_2_4_b[hebap-8][log_gain-1];
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mant += (ff_eac3_gaq_remap_2_4_a[hebap-8][log_gain-1] * (mant>>8) + b) >> 7;
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} else {
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/* small mantissa, no GAQ, or Gk=1 */
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mant <<= 24 - bits;
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if (!log_gain) {
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/* remap mantissa value for no GAQ or Gk=1 */
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mant += (ff_eac3_gaq_remap_1[hebap-8] * (mant>>8)) >> 7;
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}
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}
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s->pre_mantissa[ch][bin][blk] = mant;
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}
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}
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idct6(s->pre_mantissa[ch][bin]);
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}
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}
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int ff_eac3_parse_header(AC3DecodeContext *s)
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{
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int i, blk, ch;
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int ac3_exponent_strategy, parse_aht_info, parse_spx_atten_data;
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int parse_transient_proc_info;
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int num_cpl_blocks;
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GetBitContext *gbc = &s->gbc;
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/* An E-AC-3 stream can have multiple independent streams which the
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application can select from. each independent stream can also contain
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dependent streams which are used to add or replace channels. */
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if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) {
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av_log_missing_feature(s->avctx, "Dependent substream decoding", 1);
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return AC3_PARSE_ERROR_FRAME_TYPE;
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} else if (s->frame_type == EAC3_FRAME_TYPE_RESERVED) {
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av_log(s->avctx, AV_LOG_ERROR, "Reserved frame type\n");
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return AC3_PARSE_ERROR_FRAME_TYPE;
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}
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/* The substream id indicates which substream this frame belongs to. each
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independent stream has its own substream id, and the dependent streams
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associated to an independent stream have matching substream id's. */
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if (s->substreamid) {
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/* only decode substream with id=0. skip any additional substreams. */
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av_log_missing_feature(s->avctx, "Additional substreams", 1);
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return AC3_PARSE_ERROR_FRAME_TYPE;
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}
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if (s->bit_alloc_params.sr_code == EAC3_SR_CODE_REDUCED) {
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/* The E-AC-3 specification does not tell how to handle reduced sample
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rates in bit allocation. The best assumption would be that it is
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handled like AC-3 DolbyNet, but we cannot be sure until we have a
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sample which utilizes this feature. */
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av_log_missing_feature(s->avctx, "Reduced sampling rates", 1);
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return -1;
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}
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skip_bits(gbc, 5); // skip bitstream id
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/* volume control params */
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for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
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skip_bits(gbc, 5); // skip dialog normalization
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if (get_bits1(gbc)) {
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skip_bits(gbc, 8); // skip compression gain word
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}
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}
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/* dependent stream channel map */
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if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) {
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if (get_bits1(gbc)) {
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skip_bits(gbc, 16); // skip custom channel map
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}
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}
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/* mixing metadata */
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if (get_bits1(gbc)) {
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/* center and surround mix levels */
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if (s->channel_mode > AC3_CHMODE_STEREO) {
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skip_bits(gbc, 2); // skip preferred stereo downmix mode
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if (s->channel_mode & 1) {
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/* if three front channels exist */
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skip_bits(gbc, 3); //skip Lt/Rt center mix level
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s->center_mix_level = get_bits(gbc, 3);
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}
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if (s->channel_mode & 4) {
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/* if a surround channel exists */
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skip_bits(gbc, 3); //skip Lt/Rt surround mix level
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s->surround_mix_level = get_bits(gbc, 3);
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}
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}
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/* lfe mix level */
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if (s->lfe_on && get_bits1(gbc)) {
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// TODO: use LFE mix level
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skip_bits(gbc, 5); // skip LFE mix level code
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}
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/* info for mixing with other streams and substreams */
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if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT) {
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for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
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// TODO: apply program scale factor
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if (get_bits1(gbc)) {
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skip_bits(gbc, 6); // skip program scale factor
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}
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}
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if (get_bits1(gbc)) {
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skip_bits(gbc, 6); // skip external program scale factor
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}
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/* skip mixing parameter data */
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switch(get_bits(gbc, 2)) {
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case 1: skip_bits(gbc, 5); break;
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case 2: skip_bits(gbc, 12); break;
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case 3: {
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int mix_data_size = (get_bits(gbc, 5) + 2) << 3;
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skip_bits_long(gbc, mix_data_size);
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break;
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}
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}
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/* skip pan information for mono or dual mono source */
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if (s->channel_mode < AC3_CHMODE_STEREO) {
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for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
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if (get_bits1(gbc)) {
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/* note: this is not in the ATSC A/52B specification
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reference: ETSI TS 102 366 V1.1.1
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section: E.1.3.1.25 */
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skip_bits(gbc, 8); // skip pan mean direction index
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skip_bits(gbc, 6); // skip reserved paninfo bits
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}
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}
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}
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/* skip mixing configuration information */
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if (get_bits1(gbc)) {
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for (blk = 0; blk < s->num_blocks; blk++) {
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if (s->num_blocks == 1 || get_bits1(gbc)) {
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skip_bits(gbc, 5);
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}
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}
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}
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}
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}
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/* informational metadata */
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if (get_bits1(gbc)) {
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skip_bits(gbc, 3); // skip bit stream mode
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skip_bits(gbc, 2); // skip copyright bit and original bitstream bit
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if (s->channel_mode == AC3_CHMODE_STEREO) {
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skip_bits(gbc, 4); // skip Dolby surround and headphone mode
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}
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if (s->channel_mode >= AC3_CHMODE_2F2R) {
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skip_bits(gbc, 2); // skip Dolby surround EX mode
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}
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for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
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if (get_bits1(gbc)) {
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skip_bits(gbc, 8); // skip mix level, room type, and A/D converter type
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}
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}
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if (s->bit_alloc_params.sr_code != EAC3_SR_CODE_REDUCED) {
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skip_bits1(gbc); // skip source sample rate code
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}
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}
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/* converter synchronization flag
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If frames are less than six blocks, this bit should be turned on
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once every 6 blocks to indicate the start of a frame set.
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reference: RFC 4598, Section 2.1.3 Frame Sets */
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if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && s->num_blocks != 6) {
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skip_bits1(gbc); // skip converter synchronization flag
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}
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/* original frame size code if this stream was converted from AC-3 */
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if (s->frame_type == EAC3_FRAME_TYPE_AC3_CONVERT &&
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(s->num_blocks == 6 || get_bits1(gbc))) {
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skip_bits(gbc, 6); // skip frame size code
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}
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/* additional bitstream info */
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if (get_bits1(gbc)) {
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int addbsil = get_bits(gbc, 6);
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for (i = 0; i < addbsil + 1; i++) {
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skip_bits(gbc, 8); // skip additional bit stream info
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}
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}
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/* audio frame syntax flags, strategy data, and per-frame data */
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if (s->num_blocks == 6) {
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ac3_exponent_strategy = get_bits1(gbc);
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parse_aht_info = get_bits1(gbc);
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} else {
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/* less than 6 blocks, so use AC-3-style exponent strategy syntax, and
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do not use AHT */
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ac3_exponent_strategy = 1;
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parse_aht_info = 0;
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}
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s->snr_offset_strategy = get_bits(gbc, 2);
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parse_transient_proc_info = get_bits1(gbc);
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s->block_switch_syntax = get_bits1(gbc);
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if (!s->block_switch_syntax)
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memset(s->block_switch, 0, sizeof(s->block_switch));
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s->dither_flag_syntax = get_bits1(gbc);
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if (!s->dither_flag_syntax) {
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for (ch = 1; ch <= s->fbw_channels; ch++)
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s->dither_flag[ch] = 1;
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}
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s->dither_flag[CPL_CH] = s->dither_flag[s->lfe_ch] = 0;
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s->bit_allocation_syntax = get_bits1(gbc);
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if (!s->bit_allocation_syntax) {
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/* set default bit allocation parameters */
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s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[2];
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s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[1];
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s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab [1];
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s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[2];
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s->bit_alloc_params.floor = ff_ac3_floor_tab [7];
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}
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s->fast_gain_syntax = get_bits1(gbc);
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s->dba_syntax = get_bits1(gbc);
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s->skip_syntax = get_bits1(gbc);
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parse_spx_atten_data = get_bits1(gbc);
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/* coupling strategy occurance and coupling use per block */
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num_cpl_blocks = 0;
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if (s->channel_mode > 1) {
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for (blk = 0; blk < s->num_blocks; blk++) {
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s->cpl_strategy_exists[blk] = (!blk || get_bits1(gbc));
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if (s->cpl_strategy_exists[blk]) {
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s->cpl_in_use[blk] = get_bits1(gbc);
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} else {
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s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
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}
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num_cpl_blocks += s->cpl_in_use[blk];
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}
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} else {
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memset(s->cpl_in_use, 0, sizeof(s->cpl_in_use));
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}
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/* exponent strategy data */
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if (ac3_exponent_strategy) {
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/* AC-3-style exponent strategy syntax */
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for (blk = 0; blk < s->num_blocks; blk++) {
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for (ch = !s->cpl_in_use[blk]; ch <= s->fbw_channels; ch++) {
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s->exp_strategy[blk][ch] = get_bits(gbc, 2);
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}
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}
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} else {
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/* LUT-based exponent strategy syntax */
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int frmchexpstr;
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for (ch = !((s->channel_mode > 1) && num_cpl_blocks); ch <= s->fbw_channels; ch++) {
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frmchexpstr = get_bits(gbc, 5);
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for (blk = 0; blk < 6; blk++) {
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s->exp_strategy[blk][ch] = ff_eac3_frm_expstr[frmchexpstr][blk];
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}
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}
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}
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/* LFE exponent strategy */
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if (s->lfe_on) {
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for (blk = 0; blk < s->num_blocks; blk++) {
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s->exp_strategy[blk][s->lfe_ch] = get_bits1(gbc);
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}
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}
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/* original exponent strategies if this stream was converted from AC-3 */
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if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT &&
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(s->num_blocks == 6 || get_bits1(gbc))) {
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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skip_bits(gbc, 5); // skip converter channel exponent strategy
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}
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}
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/* determine which channels use AHT */
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if (parse_aht_info) {
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/* AHT is only available when there are 6 blocks in the frame.
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The coupling channel can only use AHT when coupling is in use for
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all blocks.
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reference: Section E3.3.2 Bit Stream Helper Variables */
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s->channel_uses_aht[CPL_CH]=0;
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for (ch = (num_cpl_blocks != 6); ch <= s->channels; ch++) {
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int nchregs = 0;
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for (blk = 0; blk < 6; blk++) {
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if (ch)
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nchregs += (s->exp_strategy[blk][ch] != EXP_REUSE);
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else
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nchregs += s->cpl_strategy_exists[blk] ||
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(s->exp_strategy[blk][CPL_CH] != EXP_REUSE);
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}
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s->channel_uses_aht[ch] = (nchregs == 1) && get_bits1(gbc);
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}
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} else {
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memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
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}
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/* per-frame SNR offset */
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if (!s->snr_offset_strategy) {
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int csnroffst = (get_bits(gbc, 6) - 15) << 4;
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int snroffst = (csnroffst + get_bits(gbc, 4)) << 2;
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for (ch = 0; ch <= s->channels; ch++)
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s->snr_offset[ch] = snroffst;
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}
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/* transient pre-noise processing data */
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if (parse_transient_proc_info) {
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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if (get_bits1(gbc)) { // channel in transient processing
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skip_bits(gbc, 10); // skip transient processing location
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skip_bits(gbc, 8); // skip transient processing length
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}
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}
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}
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/* spectral extension attenuation data */
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if (parse_spx_atten_data) {
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av_log_missing_feature(s->avctx, "Spectral extension attenuation", 1);
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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if (get_bits1(gbc)) { // channel has spx attenuation
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skip_bits(gbc, 5); // skip spx attenuation code
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}
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}
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}
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/* block start information */
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if (s->num_blocks > 1 && get_bits1(gbc)) {
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/* reference: Section E2.3.2.27
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nblkstrtbits = (numblks - 1) * (4 + ceiling(log2(words_per_frame)))
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The spec does not say what this data is or what it's used for.
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It is likely the offset of each block within the frame. */
|
||||
int block_start_bits = (s->num_blocks-1) * (4 + av_log2(s->frame_size-2));
|
||||
skip_bits(gbc, block_start_bits);
|
||||
}
|
||||
|
||||
/* syntax state initialization */
|
||||
for (ch = 1; ch <= s->fbw_channels; ch++) {
|
||||
s->first_cpl_coords[ch] = 1;
|
||||
}
|
||||
s->first_cpl_leak = 1;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user