[calls] sip: media: Allow specifying SRTP for GStreamer capabilities

[Evangelos Ribeiro Tzaras <devrtz src gnome org>]

commit 58f9f5cb62aaf96c89e1a59a40c47b51c96e8347
Author: Evangelos Ribeiro Tzaras <devrtz fortysixandtwo eu>
Date:   Thu Apr 7 11:42:18 2022 +0200

    sip: media: Allow specifying SRTP for GStreamer capabilities
    
    When using SRTP the GstCaps must be set accordingly.

 plugins/sip/calls-sip-media-pipeline.c | 2 +-
 plugins/sip/gst-rfc3551.c              | 7 +++++--
 plugins/sip/gst-rfc3551.h              | 3 ++-
 3 files changed, 8 insertions(+), 4 deletions(-)
---
diff --git a/plugins/sip/calls-sip-media-pipeline.c b/plugins/sip/calls-sip-media-pipeline.c
index 0eefa578..476dda5a 100644
--- a/plugins/sip/calls-sip-media-pipeline.c
+++ b/plugins/sip/calls-sip-media-pipeline.c
@@ -656,7 +656,7 @@ pipeline_setup_codecs (CallsSipMediaPipeline *self,
   }
 
   /* UDP src capabilities */
-  caps_string = media_codec_get_gst_capabilities (codec);
+  caps_string = media_codec_get_gst_capabilities (codec, FALSE);
   g_debug ("Capabilities:\n%s", caps_string);
 
   caps = gst_caps_from_string (caps_string);
diff --git a/plugins/sip/gst-rfc3551.c b/plugins/sip/gst-rfc3551.c
index a72b2974..d052b016 100644
--- a/plugins/sip/gst-rfc3551.c
+++ b/plugins/sip/gst-rfc3551.c
@@ -106,15 +106,18 @@ media_codec_by_payload_id (guint payload_id)
 /* media_codec_get_gst_capabilities:
  *
  * @codec: A #MediaCodecInfo
+ * @use_srtp: Whether to use SRTP
  *
  * Returns: (transfer full): The capability string describing GstCaps.
  * Used for the RTP source element.
  */
 gchar *
-media_codec_get_gst_capabilities (MediaCodecInfo *codec)
+media_codec_get_gst_capabilities (MediaCodecInfo *codec,
+                                  gboolean        use_srtp)
 {
-  return g_strdup_printf ("application/x-rtp,media=(string)audio,clock-rate=(int)%u"
+  return g_strdup_printf ("application/%s,media=(string)audio,clock-rate=(int)%u"
                           ",encoding-name=(string)%s,payload=(int)%u",
+                          use_srtp ? "x-srtp" : "x-rtp",
                           codec->clock_rate,
                           codec->name,
                           codec->payload_id);
diff --git a/plugins/sip/gst-rfc3551.h b/plugins/sip/gst-rfc3551.h
index 36d571aa..9e42d20b 100644
--- a/plugins/sip/gst-rfc3551.h
+++ b/plugins/sip/gst-rfc3551.h
@@ -47,5 +47,6 @@ typedef struct {
 gboolean        media_codec_available_in_gst (MediaCodecInfo *codec);
 MediaCodecInfo *media_codec_by_name (const char *name);
 MediaCodecInfo *media_codec_by_payload_id (uint payload_id);
-gchar          *media_codec_get_gst_capabilities (MediaCodecInfo *codec);
+gchar          *media_codec_get_gst_capabilities (MediaCodecInfo *codec,
+                                                  gboolean        use_srtp);
 GList          *media_codecs_get_candidates (void);