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
