From 8598f082781ed2f0672bbdcfbc303dfd2f64be2e Mon Sep 17 00:00:00 2001
From: Mathieu Duponchelle <mathieu@centricular.com>
Date: Mon, 9 Oct 2017 18:13:27 +0200
Subject: [PATCH] opusenc: Allow unpositioned channels.

The input will be treated as a set of mono channels,
and the channel-mapping-family will be set to 255
(no defined channel meaning)

https://bugzilla.gnome.org/show_bug.cgi?id=788720
---
 ext/opus/gstopusenc.c | 26 ++++++++++++++++++++++----
 ext/opus/gstopusenc.h |  1 +
 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/ext/opus/gstopusenc.c b/ext/opus/gstopusenc.c
index c8799aaa38..2282873b32 100644
--- a/ext/opus/gstopusenc.c
+++ b/ext/opus/gstopusenc.c
@@ -368,6 +368,7 @@ gst_opus_enc_init (GstOpusEnc * enc)
   enc->n_channels = -1;
   enc->sample_rate = -1;
   enc->frame_samples = 0;
+  enc->unpositioned = FALSE;
 
   enc->bitrate = DEFAULT_BITRATE;
   enc->bandwidth = DEFAULT_BANDWIDTH;
@@ -517,7 +518,7 @@ gst_opus_enc_setup_channel_mappings (GstOpusEnc * enc,
   gst_opus_enc_setup_trivial_mapping (enc, enc->decoding_channel_mapping);
 
   /* For one channel, use the basic RTP mapping */
-  if (enc->n_channels == 1) {
+  if (enc->n_channels == 1 && !enc->unpositioned) {
     GST_INFO_OBJECT (enc, "Mono, trivial RTP mapping");
     enc->channel_mapping_family = 0;
     /* implicit mapping for family 0 */
@@ -526,7 +527,7 @@ gst_opus_enc_setup_channel_mappings (GstOpusEnc * enc,
 
   /* For two channels, use the basic RTP mapping if the channels are
      mapped as left/right. */
-  if (enc->n_channels == 2) {
+  if (enc->n_channels == 2 && !enc->unpositioned) {
     GST_INFO_OBJECT (enc, "Stereo, trivial RTP mapping");
     enc->channel_mapping_family = 0;
     enc->n_stereo_streams = 1;
@@ -540,7 +541,7 @@ gst_opus_enc_setup_channel_mappings (GstOpusEnc * enc,
      One maps the input channels to an ordering which has the natural pairs
      first so they can benefit from the Opus stereo channel coupling, and the
      other maps this ordering to the Vorbis ordering. */
-  if (enc->n_channels >= 3 && enc->n_channels <= 8) {
+  if (enc->n_channels >= 3 && enc->n_channels <= 8 && !enc->unpositioned) {
     int c0, c1, c0v, c1v;
     int mapped;
     gboolean positions_done[256];
@@ -638,7 +639,11 @@ gst_opus_enc_setup_channel_mappings (GstOpusEnc * enc,
 
   /* For other cases, we use undefined, with the default trivial mapping
      and all mono streams */
-  GST_WARNING_OBJECT (enc, "Unknown mapping");
+  if (!enc->unpositioned)
+    GST_WARNING_OBJECT (enc, "Unknown mapping");
+  else
+    GST_INFO_OBJECT (enc, "Unpositioned mapping, all channels mono");
+
   enc->channel_mapping_family = 255;
   enc->n_stereo_streams = 0;
 
@@ -655,6 +660,7 @@ gst_opus_enc_set_format (GstAudioEncoder * benc, GstAudioInfo * info)
   g_mutex_lock (&enc->property_lock);
 
   enc->n_channels = GST_AUDIO_INFO_CHANNELS (info);
+  enc->unpositioned = GST_AUDIO_INFO_IS_UNPOSITIONED (info);
   enc->sample_rate = GST_AUDIO_INFO_RATE (info);
   gst_opus_enc_setup_channel_mappings (enc, info);
   GST_DEBUG_OBJECT (benc, "Setup with %d channels, %d Hz", enc->n_channels,
@@ -866,6 +872,18 @@ gst_opus_enc_get_sink_template_caps (void)
       gst_structure_set (s, "channels", G_TYPE_INT, i, "channel-mask",
           GST_TYPE_BITMASK, channel_mask, NULL);
       gst_caps_append_structure (caps, s);
+
+      /* We also allow unpositioned channels, input will be
+       * treated as a set of individual mono channels */
+      s = gst_structure_copy (s2);
+      gst_structure_set (s, "channels", G_TYPE_INT, i, "channel-mask",
+          GST_TYPE_BITMASK, 0x0, NULL);
+      gst_caps_append_structure (caps, s);
+
+      s = gst_structure_copy (s1);
+      gst_structure_set (s, "channels", G_TYPE_INT, i, "channel-mask",
+          GST_TYPE_BITMASK, 0x0, NULL);
+      gst_caps_append_structure (caps, s);
     }
 
     gst_structure_free (s1);
diff --git a/ext/opus/gstopusenc.h b/ext/opus/gstopusenc.h
index f447292af4..fd21b7c6a8 100644
--- a/ext/opus/gstopusenc.h
+++ b/ext/opus/gstopusenc.h
@@ -78,6 +78,7 @@ struct _GstOpusEnc {
   gint                  frame_samples;
   gint                  n_channels;
   gint                  sample_rate;
+  gboolean              unpositioned;
 
   guint64               encoded_samples, consumed_samples;
   guint16               lookahead, pending_lookahead;