opus: add an option to toggle intensity stereo phase inversion

Due to a somewhat high volume of complains, phase inversion has
been made optional with RFC8251. This allows for better bass
frequency response when partially downmixing to play on systems
with an LFE speaker.

Signed-off-by: Rostislav Pehlivanov <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/libavcodec/opus_pvq.c b/libavcodec/opus_pvq.c
index 2f7aa74da4..449215f814 100644
--- a/libavcodec/opus_pvq.c
+++ b/libavcodec/opus_pvq.c
@@ -643,6 +643,7 @@ static av_always_inline uint32_t quant_band_template(CeltPVQ *pvq, CeltFrame *f,
                 }
             } else {
                 inv = (b > 2 << 3 && f->remaining2 > 2 << 3) ? ff_opus_rc_dec_log(rc, 2) : 0;
+                inv = f->apply_phase_inv ? inv : 0;
             }
             itheta = 0;
         }