From 478b78c77e32612d84f2bfa7cc7dcc70ed59d5fb Mon Sep 17 00:00:00 2001
From: Nirbheek Chauhan <nirbheek@centricular.com>
Date: Tue, 22 Jul 2014 20:25:52 +0530
Subject: encode: POC for streaming incoming video streams to RTP/UDP

The UDP broadcast happens to localhost:5004 by default. Doesn't handle multiple
video streams properly yet, because this is a POC.
---
 src/encode.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)

diff --git a/src/encode.c b/src/encode.c
index 915cd00..2de4a9a 100644
--- a/src/encode.c
+++ b/src/encode.c
@@ -95,6 +95,109 @@ out:
   return;
 }
 
+static GstPadProbeReturn
+on_pad_probe_buffer (GstPad          *pad,
+                     GstPadProbeInfo *info,
+                     gpointer         user_data)
+{
+  GstBuffer *buffer;
+  static int count;
+  
+  /* Due to a bug, the DISCONT flag is set on the first two buffers,
+   * which matroskademux doesn't handle properly. So, we rewrite that flag. */
+  buffer = gst_pad_probe_info_get_buffer (info);
+  if (GST_BUFFER_FLAG_IS_SET (buffer, GST_BUFFER_FLAG_DISCONT))
+    count++;
+  GST_BUFFER_FLAG_UNSET (buffer, GST_BUFFER_FLAG_DISCONT);
+
+  if (count != 2)
+    return GST_PAD_PROBE_PASS;
+  else
+    return GST_PAD_PROBE_REMOVE;
+}
+
+static void
+on_demuxer_pad_added (GstElement *demuxer,
+                      GstPad     *srcpad,
+                      GstElement *pipeline)
+{
+  char *name;
+  GstCaps *caps;
+  GstPad *sinkpad;
+  GstElement *rtppay, *udpsink;
+
+  caps = gst_pad_query_caps (srcpad, NULL);
+  name = gst_caps_to_string (caps);
+
+  g_debug ("Pad added: %s\n", name);
+  if (!g_str_has_prefix (name, "video/x-vp8"))
+    goto out;
+
+  /* Broadcast VP8 RTP over UDP://localhost:5004 */
+  rtppay = gst_element_factory_make ("rtpvp8pay", "rtpvp8pay");
+  udpsink = gst_element_factory_make ("udpsink", "udpsink");
+  gst_bin_add_many (GST_BIN (pipeline), rtppay, udpsink, NULL);
+  gst_element_link (rtppay, udpsink);
+
+  if (!gst_element_sync_state_with_parent (rtppay) ||
+      !gst_element_sync_state_with_parent (udpsink)) {
+    g_critical ("Unable to sync rtppay ! udpsink with parent pipeline\n");
+    goto out;
+  }
+
+  sinkpad = gst_element_get_static_pad (rtppay, "sink");
+  gst_pad_link (srcpad, sinkpad);
+  stp_print_status ("Streaming a vp8 stream on UDP\n");
+out:
+  g_free (name);
+  gst_object_unref (sinkpad);
+}
+
+static void
+do_udp_rtp_broadcast (GstElement *decodebin,
+                      GstElement *pipeline)
+{
+  GstPadTemplate *template;
+  GstPad *srcpad, *sinkpad;
+  GstElement *demuxer, *q, *tee;
+
+  /* We demux the encode stream, and rtp all the vp8 streams we find.
+   * Hacky, but quick for this POC. */
+  q = gst_element_factory_make ("queue", "rtpq");
+  /*demuxer = gst_element_factory_make ("filesink", "matroskademux");
+  g_object_set (demuxer, "location", "filesink.webm", NULL);*/
+  demuxer = gst_element_factory_make ("matroskademux", "matroskademux");
+
+  gst_bin_add_many (GST_BIN (pipeline), q, demuxer, NULL);
+  gst_element_link (q, demuxer);
+
+  tee = gst_bin_get_by_name (GST_BIN (pipeline), "tee");
+  template = gst_pad_template_new ("teesrc", GST_PAD_SRC,
+                                   GST_PAD_REQUEST, GST_CAPS_ANY);
+  srcpad = gst_element_request_pad (tee, template, NULL, GST_CAPS_ANY);
+  sinkpad = gst_element_get_static_pad (q, "sink");
+
+  if (!gst_element_sync_state_with_parent (q) ||
+      !gst_element_sync_state_with_parent (demuxer)) {
+    g_critical ("Unable to sync q ! demuxer with parent pipeline\n");
+    goto out;
+  }
+
+  gst_pad_link (srcpad, sinkpad);
+
+  /* Due to a bug in webmmux, DISCONT is sent repeatedly for no reason */
+  gst_pad_add_probe (srcpad, GST_PAD_PROBE_TYPE_BUFFER,
+                     (GstPadProbeCallback) on_pad_probe_buffer, NULL, NULL);
+
+  g_signal_connect (demuxer, "pad-added",
+                    G_CALLBACK (on_demuxer_pad_added), pipeline);
+
+out:
+  gst_object_unref (template);
+  gst_object_unref (srcpad);
+  gst_object_unref (tee);
+}
+
 static GstEncodingProfile *
 create_webm_profile (void)
 {
@@ -219,6 +322,9 @@ stp_encode_from_msg (TranscodeServerCtx *ctx)
    * corresponding sink pad on decodebin */
   g_signal_connect (decodebin, "pad-added",
                     G_CALLBACK (on_decodebin_pad_added), encodebin);
+  /* When finished adding pads, try streaming it all over RTP/UDP */
+  g_signal_connect (decodebin, "no-more-pads",
+                    G_CALLBACK (do_udp_rtp_broadcast), ctx->pipeline);
 
   bus = gst_pipeline_get_bus (GST_PIPELINE (ctx->pipeline));
   gst_bus_add_signal_watch (bus);
-- 
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