diff options
Diffstat (limited to 'libavcodec/aac.c')
| -rw-r--r-- | libavcodec/aac.c | 38 |
1 files changed, 37 insertions, 1 deletions
diff --git a/libavcodec/aac.c b/libavcodec/aac.c index 27d8cee266..61c27638f6 100644 --- a/libavcodec/aac.c +++ b/libavcodec/aac.c @@ -1104,6 +1104,42 @@ static int decode_extension_payload(AACContext * ac, GetBitContext * gb, int cnt return res; } +/** + * Decode Temporal Noise Shaping filter coefficients and apply all-pole filters; reference: 4.6.9.3. + * + * @param decode 1 if tool is used normally, 0 if tool is used in LTP. + * @param coef spectral coefficients + */ +static void apply_tns(float coef[1024], TemporalNoiseShaping * tns, IndividualChannelStream * ics, int decode) { + const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb); + int w, filt, m, i, ib; + int bottom, top, order, start, end, size, inc; + float lpc[TNS_MAX_ORDER]; + + for (w = 0; w < ics->num_windows; w++) { + bottom = ics->num_swb; + for (filt = 0; filt < tns->n_filt[w]; filt++) { + top = bottom; + bottom = FFMAX(0, top - tns->length[w][filt]); + order = tns->order[w][filt]; + if (order == 0) + continue; + + /* tns_decode_coef + * FIXME: This duplicates the functionality of some double code in lpc.c. + */ + for (m = 0; m < order; m++) { + float tmp; + lpc[m] = tns->coef[w][filt][m]; + for (i = 0; i < m/2; i++) { + tmp = lpc[i]; + lpc[i] += lpc[m] * lpc[m-1-i]; + lpc[m-1-i] += lpc[m] * tmp; + } + if(m & 1) + lpc[i] += lpc[m] * lpc[i]; + } + start = ics->swb_offset[FFMIN(bottom, mmm)]; end = ics->swb_offset[FFMIN( top, mmm)]; if ((size = end - start) <= 0) @@ -1118,7 +1154,7 @@ static int decode_extension_payload(AACContext * ac, GetBitContext * gb, int cnt // ar filter for (m = 0; m < size; m++, start += inc) for (i = 1; i <= FFMIN(m, order); i++) - coef[start] -= coef[start - i*inc] * lpc[i]; + coef[start] -= coef[start - i*inc] * lpc[i-1]; } } } |