[FFmpeg-devel] [PATCH] libopus: support disabling phase inversion.

[mrdegier at gmail.com]

From: Menno <mrdegier at gmail.com>

Signed-off-by: Menno <mrdegier at gmail.com>
---
 doc/encoders.texi       |  5 +++++
 libavcodec/libopusenc.c | 14 ++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/doc/encoders.texi b/doc/encoders.texi
index 6a410a8cb6..5cd8b1a064 100644
--- a/doc/encoders.texi
+++ b/doc/encoders.texi
@@ -981,6 +981,11 @@ Other values include 0 for mono and stereo, 1 for surround sound with masking
 and LFE bandwidth optimizations, and 255 for independent streams with an
 unspecified channel layout.
 
+ at item disable_phase_inversion (N.A.) (requires libopus >= 1.2)
+If set to 1, disables the use of phase inversion for intensity stereo,
+improving the quality of mono downmixes, but slightly reducing normal stereo
+quality. The default is 0 (phase inversion enabled).
+
 @end table
 
 @anchor{libshine}
diff --git a/libavcodec/libopusenc.c b/libavcodec/libopusenc.c
index b449497d15..3ad10502fc 100644
--- a/libavcodec/libopusenc.c
+++ b/libavcodec/libopusenc.c
@@ -39,6 +39,9 @@ typedef struct LibopusEncOpts {
     int packet_size;
     int max_bandwidth;
     int mapping_family;
+#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
+    int disable_phase_inversion;
+#endif
 } LibopusEncOpts;
 
 typedef struct LibopusEncContext {
@@ -154,6 +157,14 @@ static int libopus_configure_encoder(AVCodecContext *avctx, OpusMSEncoder *enc,
                    "Unable to set maximum bandwidth: %s\n", opus_strerror(ret));
     }
 
+#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
+    ret = opus_multistream_encoder_ctl(enc,
+                                       OPUS_SET_PHASE_INVERSION_DISABLED(opts->disable_phase_inversion));
+    if (ret != OPUS_OK)
+        av_log(avctx, AV_LOG_WARNING,
+               "Unable to disable phase inversion: %s\n",
+               opus_strerror(ret));
+#endif
     return OPUS_OK;
 }
 
@@ -530,6 +541,9 @@ static const AVOption libopus_options[] = {
         { "on",             "Use variable bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, FLAGS, "vbr" },
         { "constrained",    "Use constrained VBR",   0, AV_OPT_TYPE_CONST, { .i64 = 2 }, 0, 0, FLAGS, "vbr" },
     { "mapping_family", "Channel Mapping Family",              OFFSET(mapping_family), AV_OPT_TYPE_INT,   { .i64 = -1 },   -1,  255,  FLAGS, "mapping_family" },
+#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
+    { "disable_phase_inversion", "Disable phase inversion",              OFFSET(disable_phase_inversion), AV_OPT_TYPE_INT,   { .i64 = 0 },   0,  1,  FLAGS  },
+#endif
     { NULL },
 };
 
-- 
2.14.1