When downmixing to mono, don't put the channels out of phase, as they will cancel out and create audible artifacts. (See RFC 8251 sec.10.)
Signed-off-by: Andrew D'Addesio <modchip...@gmail.com> --- libavcodec/opus_celt.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/libavcodec/opus_celt.c b/libavcodec/opus_celt.c index 4ba4fde..d58b8e9 100644 --- a/libavcodec/opus_celt.c +++ b/libavcodec/opus_celt.c @@ -1445,6 +1445,12 @@ static unsigned int celt_decode_band(CeltContext *s, OpusRangeCoder *rc, Let's do that at higher complexity */ } else if (dualstereo) { inv = (b > 2 << 3 && s->remaining2 > 2 << 3) ? opus_rc_p2model(rc, 2) : 0; + + /* Don't put the channels out of phase if we are downmixing to mono + as this subjectively sounds bad (RFC 8251 section 10). */ + if (s->output_channels == 1) + inv = 0; + itheta = 0; } qalloc = opus_rc_tell_frac(rc) - tell; -- 2.15.1.windows.2 _______________________________________________ libav-devel mailing list libav-devel@libav.org https://lists.libav.org/mailman/listinfo/libav-devel