On Fri, Aug 5, 2011 at 9:24 PM, Nathan Caldwell <[email protected]> wrote: > > On Fri, Jul 29, 2011 at 8:39 PM, Nathan Caldwell <[email protected]> wrote: > > On Fri, Jul 29, 2011 at 3:30 PM, Alex Converse <[email protected]> > > wrote: > >> On Fri, Jul 29, 2011 at 1:58 PM, Nathan Caldwell <[email protected]> > >> wrote: > >>> The spec states: > >>> > >>> * Only the lowest 12 spectral coefficients of any LFE may be non-zero > >>> > >>> We were using the 12 lowest *bands*. > >>> --- > >>> libavcodec/aacenc.c | 10 +++++++++- > >>> 1 files changed, 9 insertions(+), 1 deletions(-) > >>> > >>> diff --git a/libavcodec/aacenc.c b/libavcodec/aacenc.c > >>> index e74af0b..7b3794f 100644 > >>> --- a/libavcodec/aacenc.c > >>> +++ b/libavcodec/aacenc.c > >>> @@ -540,6 +540,14 @@ 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 */ > >>> + if (s->sample_rate_index >= 11) > >>> + ics->num_swb = 1; > >>> + else if (s->sample_rate_index >= 8) > >>> + ics->num_swb = 2; /* This actually results in 16 > >>> coefficients */ > >> > >> Should we play it safe and only use 8 here? Can we zero out 13-16 > >> after the fact? > > > > I like using 8, if only because it simplifies the logic. That still > > gives us up to 112Hz on the high end and 77Hz on the low end at those > > sample rates. Not ideal, but should be fine. > > > > Attached. > > > Ping? >
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