From 06c72f83d79e38b0421fdfe1d4b1bf8f5bf3b9c9 Mon Sep 17 00:00:00 2001
From: Jason Locklin <jalockli@uwaterloo.ca>
Date: Fri, 31 Jul 2015 10:50:37 -0400
Subject: OPUS_APPLICATION_VOIP should be used

See: http://opus-codec.org/docs/html_api-1.0.1/group__opus__encoder.html#gaa89264fd93c9da70362a0c9b96b9ca88

"VOIP" rather than "AUDIO":
> gives best quality at a given bitrate for voice signals. It enhances the input signal by high-pass filtering and emphasizing formants and harmonics. Optionally it includes in-band forward error correction to protect against packet loss. Use this mode for typical VoIP applications.
---
 toxav/codec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/toxav/codec.c b/toxav/codec.c
index ae146ccf..71d24e87 100644
--- a/toxav/codec.c
+++ b/toxav/codec.c
@@ -294,7 +294,7 @@ static int init_audio_encoder(CSSession *cs)
 {
     int rc = OPUS_OK;
     cs->audio_encoder = opus_encoder_create(cs->audio_encoder_sample_rate,
-                                            cs->audio_encoder_channels, OPUS_APPLICATION_AUDIO, &rc);
+                                            cs->audio_encoder_channels, OPUS_APPLICATION_VOIP, &rc);
 
     if ( rc != OPUS_OK ) {
         LOGGER_ERROR("Error while starting audio encoder: %s", opus_strerror(rc));
-- 
cgit v1.2.3


From bcb864af4ac51fb78cdac9df249949d6fbca937a Mon Sep 17 00:00:00 2001
From: Jason Locklin <jalockli@uwaterloo.ca>
Date: Fri, 31 Jul 2015 11:01:32 -0400
Subject: Enable in-band FEC

In-band FEC can be used with OPUS_APPLICATION_VOIP to improve Codec robustness to packet loss and corruption. It is disabled by default:

http://opus-codec.org/docs/html_api-1.0.1/group__opus__encoderctls.html#ga5b67dc832aa46c1c2f35752c46380545
---
 toxav/codec.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/toxav/codec.c b/toxav/codec.c
index 71d24e87..7b76929c 100644
--- a/toxav/codec.c
+++ b/toxav/codec.c
@@ -303,6 +303,13 @@ static int init_audio_encoder(CSSession *cs)
 
     rc = opus_encoder_ctl(cs->audio_encoder, OPUS_SET_BITRATE(cs->audio_encoder_bitrate));
 
+    if ( rc != OPUS_OK ) {
+        LOGGER_ERROR("Error while setting encoder ctl: %s", opus_strerror(rc));
+        return -1;
+    }
+    
+    rc = opus_encoder_ctl(cs->audio_encoder, OPUS_SET_INBAND_FEC(1));
+
     if ( rc != OPUS_OK ) {
         LOGGER_ERROR("Error while setting encoder ctl: %s", opus_strerror(rc));
         return -1;
-- 
cgit v1.2.3


From ef086a5897ab2f3296ba777e7e1229384981313c Mon Sep 17 00:00:00 2001
From: Jason Locklin <jalockli@uwaterloo.ca>
Date: Fri, 31 Jul 2015 11:08:51 -0400
Subject: Set packet loss percentage

Make the Codec resistant to up to 10% packet loss (default 0) at the expense of some bandwidth.  10% is aggressive (1-5% should be typical for voip systems, but can be higher when users are on WiFi connections. This could also be adjusted on the fly, rather than hard-coded, with feedback from the receiving client.
---
 toxav/codec.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/toxav/codec.c b/toxav/codec.c
index 7b76929c..9f705db4 100644
--- a/toxav/codec.c
+++ b/toxav/codec.c
@@ -315,6 +315,14 @@ static int init_audio_encoder(CSSession *cs)
         return -1;
     }
 
+    /* Make codec resistant to up to 10% packet loss */
+    rc = opus_encoder_ctl(cs->audio_encoder, OPUS_SET_PACKET_LOSS_PERC(10));
+
+    if ( rc != OPUS_OK ) {
+        LOGGER_ERROR("Error while setting encoder ctl: %s", opus_strerror(rc));
+        return -1;
+    }
+
     rc = opus_encoder_ctl(cs->audio_encoder, OPUS_SET_COMPLEXITY(10));
 
     if ( rc != OPUS_OK ) {
-- 
cgit v1.2.3


From f05fdae055cb01ed03008d964485dfda16b2df18 Mon Sep 17 00:00:00 2001
From: Jason Locklin <jalockli@uwaterloo.ca>
Date: Fri, 31 Jul 2015 11:11:32 -0400
Subject: added documentation

---
 toxav/codec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/toxav/codec.c b/toxav/codec.c
index 9f705db4..81bbede6 100644
--- a/toxav/codec.c
+++ b/toxav/codec.c
@@ -308,6 +308,7 @@ static int init_audio_encoder(CSSession *cs)
         return -1;
     }
     
+    /* Enable in-band forward error correction in codec */
     rc = opus_encoder_ctl(cs->audio_encoder, OPUS_SET_INBAND_FEC(1));
 
     if ( rc != OPUS_OK ) {
@@ -323,6 +324,7 @@ static int init_audio_encoder(CSSession *cs)
         return -1;
     }
 
+    /* Set algorithm to the highest complexity, maximizing compression */
     rc = opus_encoder_ctl(cs->audio_encoder, OPUS_SET_COMPLEXITY(10));
 
     if ( rc != OPUS_OK ) {
-- 
cgit v1.2.3