From 2502e13b073370edd62451808ed286f2d7d7a196 Mon Sep 17 00:00:00 2001
From: Lynne <dev@lynne.ee>
Date: Mon, 25 May 2020 14:41:33 +0100
Subject: [PATCH] opusenc: add apply_phase_inv option

By popular request.
Does the same as in libopusenc.
---
 libavcodec/opus_pvq.c | 2 +-
 libavcodec/opusenc.c  | 3 ++-
 libavcodec/opusenc.h  | 1 +
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavcodec/opus_pvq.c b/libavcodec/opus_pvq.c
index 9c21d67298..a4ab7c46eb 100644
--- a/libavcodec/opus_pvq.c
+++ b/libavcodec/opus_pvq.c
@@ -627,7 +627,7 @@ static av_always_inline uint32_t quant_band_template(CeltPVQ *pvq, CeltFrame *f,
             }
         } else if (stereo) {
             if (quant) {
-                inv = itheta > 8192;
+                inv = f->apply_phase_inv ? itheta > 8192 : 0;
                  if (inv) {
                     for (i = 0; i < N; i++)
                        Y[i] *= -1;
diff --git a/libavcodec/opusenc.c b/libavcodec/opusenc.c
index 3c08ebcf69..953749af3a 100644
--- a/libavcodec/opusenc.c
+++ b/libavcodec/opusenc.c
@@ -691,7 +691,7 @@ static av_cold int opus_encode_init(AVCodecContext *avctx)
         s->frame[i].avctx = s->avctx;
         s->frame[i].seed = 0;
         s->frame[i].pvq = s->pvq;
-        s->frame[i].apply_phase_inv = 1;
+        s->frame[i].apply_phase_inv = s->options.apply_phase_inv;
         s->frame[i].block[0].emph_coeff = s->frame[i].block[1].emph_coeff = 0.0f;
     }
 
@@ -701,6 +701,7 @@ static av_cold int opus_encode_init(AVCodecContext *avctx)
 #define OPUSENC_FLAGS AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM
 static const AVOption opusenc_options[] = {
     { "opus_delay", "Maximum delay in milliseconds", offsetof(OpusEncContext, options.max_delay_ms), AV_OPT_TYPE_FLOAT, { .dbl = OPUS_MAX_LOOKAHEAD }, 2.5f, OPUS_MAX_LOOKAHEAD, OPUSENC_FLAGS, "max_delay_ms" },
+    { "apply_phase_inv", "Apply intensity stereo phase inversion", offsetof(OpusEncContext, options.apply_phase_inv), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, OPUSENC_FLAGS, "apply_phase_inv" },
     { NULL },
 };
 
diff --git a/libavcodec/opusenc.h b/libavcodec/opusenc.h
index b9162ebec6..b623b3e948 100644
--- a/libavcodec/opusenc.h
+++ b/libavcodec/opusenc.h
@@ -42,6 +42,7 @@
 
 typedef struct OpusEncOptions {
     float max_delay_ms;
+    int apply_phase_inv;
 } OpusEncOptions;
 
 typedef struct OpusPacketInfo {