diff options
author | Carl Eugen Hoyos <cehoyos@rainbow.studorg.tuwien.ac.at> | 2010-03-31 02:09:14 +0400 |
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committer | Carl Eugen Hoyos <cehoyos@rainbow.studorg.tuwien.ac.at> | 2010-03-31 02:09:14 +0400 |
commit | ca6e7708b42e7d33ba3053bcd447d52a077bca25 (patch) | |
tree | 7d7b95250ce17fbfb3cd66a8be480af5825e58c8 /libavcodec/ac3dec.c | |
parent | 1052b76f0f4142942f0fc2481a4e377a6839b954 (diff) |
Add spectral extension to the E-AC-3 decoder.
Original patch by Justin, updated and resubmitted by
Christophe Gisquet, christophe D gisquet A gmail
Originally committed as revision 22734 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/ac3dec.c')
-rw-r--r-- | libavcodec/ac3dec.c | 119 |
1 files changed, 109 insertions, 10 deletions
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c index 9f45af3280..1656a4c540 100644 --- a/libavcodec/ac3dec.c +++ b/libavcodec/ac3dec.c @@ -815,14 +815,105 @@ static int decode_audio_block(AC3DecodeContext *s, int blk) /* spectral extension strategy */ if (s->eac3 && (!blk || get_bits1(gbc))) { - if (get_bits1(gbc)) { - av_log_missing_feature(s->avctx, "Spectral extension", 1); - return -1; + s->spx_in_use = get_bits1(gbc); + if (s->spx_in_use) { + int dst_start_freq, dst_end_freq, src_start_freq, + start_subband, end_subband; + + /* determine which channels use spx */ + if (s->channel_mode == AC3_CHMODE_MONO) { + s->channel_uses_spx[1] = 1; + } else { + for (ch = 1; ch <= fbw_channels; ch++) + s->channel_uses_spx[ch] = get_bits1(gbc); + } + + /* get the frequency bins of the spx copy region and the spx start + and end subbands */ + dst_start_freq = get_bits(gbc, 2); + start_subband = get_bits(gbc, 3) + 2; + if (start_subband > 7) + start_subband += start_subband - 7; + end_subband = get_bits(gbc, 3) + 5; + if (end_subband > 7) + end_subband += end_subband - 7; + dst_start_freq = dst_start_freq * 12 + 25; + src_start_freq = start_subband * 12 + 25; + dst_end_freq = end_subband * 12 + 25; + + /* check validity of spx ranges */ + if (start_subband >= end_subband) { + av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension " + "range (%d >= %d)\n", start_subband, end_subband); + return -1; + } + if (dst_start_freq >= src_start_freq) { + av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension " + "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq); + return -1; + } + + s->spx_dst_start_freq = dst_start_freq; + s->spx_src_start_freq = src_start_freq; + s->spx_dst_end_freq = dst_end_freq; + + decode_band_structure(gbc, blk, s->eac3, 0, + start_subband, end_subband, + ff_eac3_default_spx_band_struct, + &s->num_spx_bands, + s->spx_band_sizes); + } else { + for (ch = 1; ch <= fbw_channels; ch++) { + s->channel_uses_spx[ch] = 0; + s->first_spx_coords[ch] = 1; + } } - /* TODO: parse spectral extension strategy info */ } - /* TODO: spectral extension coordinates */ + /* spectral extension coordinates */ + if (s->spx_in_use) { + for (ch = 1; ch <= fbw_channels; ch++) { + if (s->channel_uses_spx[ch]) { + if (s->first_spx_coords[ch] || get_bits1(gbc)) { + float spx_blend; + int bin, master_spx_coord; + + s->first_spx_coords[ch] = 0; + spx_blend = get_bits(gbc, 5) * (1.0f/32); + master_spx_coord = get_bits(gbc, 2) * 3; + + bin = s->spx_src_start_freq; + for (bnd = 0; bnd < s->num_spx_bands; bnd++) { + int bandsize; + int spx_coord_exp, spx_coord_mant; + float nratio, sblend, nblend, spx_coord; + + /* calculate blending factors */ + bandsize = s->spx_band_sizes[bnd]; + nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend; + nratio = av_clipf(nratio, 0.0f, 1.0f); + nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance + sblend = sqrtf(1.0f - nratio); + bin += bandsize; + + /* decode spx coordinates */ + spx_coord_exp = get_bits(gbc, 4); + spx_coord_mant = get_bits(gbc, 2); + if (spx_coord_exp == 15) spx_coord_mant <<= 1; + else spx_coord_mant += 4; + spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord); + spx_coord = spx_coord_mant * (1.0f/(1<<23)); + + /* multiply noise and signal blending factors by spx coordinate */ + s->spx_noise_blend [ch][bnd] = nblend * spx_coord; + s->spx_signal_blend[ch][bnd] = sblend * spx_coord; + } + } + } else { + s->first_spx_coords[ch] = 1; + } + } + } /* coupling strategy */ if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) { @@ -859,9 +950,9 @@ static int decode_audio_block(AC3DecodeContext *s, int blk) s->phase_flags_in_use = get_bits1(gbc); /* coupling frequency range */ - /* TODO: modify coupling end freq if spectral extension is used */ cpl_start_subband = get_bits(gbc, 4); - cpl_end_subband = get_bits(gbc, 4) + 3; + cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 : + get_bits(gbc, 4) + 3; if (cpl_start_subband >= cpl_end_subband) { av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n", cpl_start_subband, cpl_end_subband); @@ -934,8 +1025,11 @@ static int decode_audio_block(AC3DecodeContext *s, int blk) if (channel_mode == AC3_CHMODE_STEREO) { if ((s->eac3 && !blk) || get_bits1(gbc)) { s->num_rematrixing_bands = 4; - if(cpl_in_use && s->start_freq[CPL_CH] <= 61) + if (cpl_in_use && s->start_freq[CPL_CH] <= 61) { s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37); + } else if (s->spx_in_use && s->spx_src_start_freq <= 61) { + s->num_rematrixing_bands--; + } for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) s->rematrixing_flags[bnd] = get_bits1(gbc); } else if (!blk) { @@ -960,6 +1054,8 @@ static int decode_audio_block(AC3DecodeContext *s, int blk) int prev = s->end_freq[ch]; if (s->channel_in_cpl[ch]) s->end_freq[ch] = s->start_freq[CPL_CH]; + else if (s->channel_uses_spx[ch]) + s->end_freq[ch] = s->spx_src_start_freq; else { int bandwidth_code = get_bits(gbc, 6); if (bandwidth_code > 60) { @@ -1156,8 +1252,6 @@ static int decode_audio_block(AC3DecodeContext *s, int blk) /* TODO: generate enhanced coupling coordinates and uncouple */ - /* TODO: apply spectral extension */ - /* recover coefficients if rematrixing is in use */ if(s->channel_mode == AC3_CHMODE_STEREO) do_rematrixing(s); @@ -1173,6 +1267,11 @@ static int decode_audio_block(AC3DecodeContext *s, int blk) s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256); } + /* apply spectral extension to high frequency bins */ + if (s->spx_in_use) { + ff_eac3_apply_spectral_extension(s); + } + /* downmix and MDCT. order depends on whether block switching is used for any channel in this block. this is because coefficients for the long and short transforms cannot be mixed. */ |