opusenc: Reverse channel order in template caps

We want to make it so that we prefer a higher, not lower, number of
channels. Otherwise, this pipeline would convert from 2 to 1 channels:

gst-launch-1.0 audiotestsrc ! audio/x-raw,channels=2 ! opusenc ! queue ! opusdec ! queue ! opusenc ! fakesink

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3494>

diff --git a/subprojects/gst-plugins-base/ext/opus/gstopusenc.c b/subprojects/gst-plugins-base/ext/opus/gstopusenc.c
index 6f1fc2b..5476106 100644 (file)
--- a/subprojects/gst-plugins-base/ext/opus/gstopusenc.c
+++ b/subprojects/gst-plugins-base/ext/opus/gstopusenc.c
@@ -857,17 +857,8 @@ gst_opus_enc_get_sink_template_caps (void)
     g_value_unset (&rate_array);
     g_value_unset (&v);
 
-    /* Mono */
-    s = gst_structure_copy (s1);
-    gst_structure_set (s, "channels", G_TYPE_INT, 1, NULL);
-    gst_caps_append_structure (caps, s);
-
-    s = gst_structure_copy (s2);
-    gst_structure_set (s, "channels", G_TYPE_INT, 1, NULL);
-    gst_caps_append_structure (caps, s);
-
     /* Stereo and further */
-    for (i = 2; i <= 8; i++) {
+    for (i = 8; i >= 2; i--) {
       guint64 channel_mask = 0;
       const GstAudioChannelPosition *pos = gst_opus_channel_positions[i - 1];
 
@@ -898,6 +889,14 @@ gst_opus_enc_get_sink_template_caps (void)
       gst_caps_append_structure (caps, s);
     }
 
+    /* Mono */
+    s = gst_structure_copy (s1);
+    gst_structure_set (s, "channels", G_TYPE_INT, 1, NULL);
+    gst_caps_append_structure (caps, s);
+
+    s = gst_structure_copy (s2);
+    gst_structure_set (s, "channels", G_TYPE_INT, 1, NULL);
+    gst_caps_append_structure (caps, s);
     gst_structure_free (s1);
     gst_structure_free (s2);