diff options
| author | Nathan Caldwell <saintdev@gmail.com> | 2011-07-29 14:49:04 -0600 |
|---|---|---|
| committer | Alex Converse <alex.converse@gmail.com> | 2011-08-13 19:40:33 -0700 |
| commit | 24efdea7fd024431f8ddd2b08c9390eba08c91f1 (patch) | |
| tree | aff5a6b5c2660b0a8ac176d0022ce8d555269629 /libavcodec/aacenc.c | |
| parent | 51a1d4d94afe536b46c96299f4b50ca26e471fef (diff) | |
aacenc: Fix number of coefficients used in a LFE channel.
The spec states:
* Only the lowest 12 spectral coefficients of any LFE may be non-zero
We were using the 12 lowest *bands*.
Diffstat (limited to 'libavcodec/aacenc.c')
| -rw-r--r-- | libavcodec/aacenc.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/libavcodec/aacenc.c b/libavcodec/aacenc.c index 5a1fc94eb5..449b200b41 100644 --- a/libavcodec/aacenc.c +++ b/libavcodec/aacenc.c @@ -540,6 +540,12 @@ static int aac_encode_frame(AVCodecContext *avctx, wi[ch].window_shape = 0; wi[ch].num_windows = 1; wi[ch].grouping[0] = 1; + + /* Only the lowest 12 coefficients are used in a LFE channel. + * The expression below results in only the bottom 8 coefficients + * being used for 11.025kHz to 16kHz sample rates. + */ + ics->num_swb = s->samplerate_index >= 8 ? 1 : 3; } else { wi[ch] = s->psy.model->window(&s->psy, samples2, la, cur_channel, ics->window_sequence[0]); @@ -550,7 +556,7 @@ static int aac_encode_frame(AVCodecContext *avctx, ics->use_kb_window[0] = wi[ch].window_shape; ics->num_windows = wi[ch].num_windows; ics->swb_sizes = s->psy.bands [ics->num_windows == 8]; - ics->num_swb = tag == TYPE_LFE ? 12 : s->psy.num_bands[ics->num_windows == 8]; + ics->num_swb = tag == TYPE_LFE ? ics->num_swb : s->psy.num_bands[ics->num_windows == 8]; for (w = 0; w < ics->num_windows; w++) ics->group_len[w] = wi[ch].grouping[w]; |