From c48760ecabc3117f97d10ed38424f4ff481296d9 Mon Sep 17 00:00:00 2001
From: Matthew Clark <matthew1000@gmail.com>
Date: Fri, 23 Feb 2018 08:07:36 +0000
Subject: [PATCH] Move to compositor and add audio example

---
 mixing.md | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/mixing.md b/mixing.md
index 61a2ceb..6fe0e9f 100644
--- a/mixing.md
+++ b/mixing.md
@@ -1,5 +1,9 @@
 # Mixing video (GStreamer command-line cheat sheet)
 
+The element `compositor` allows video to be mixed (overlayed, put side-by-side, etc).
+
+The older `videomixer` element can be used instead, and takes the same arguments as `compositor` so it's easy to swap between them. However, `videomixer` is apparently inferior in some situations, such as for live streams.
+
 ### Picture in picture
 
 Here we have two source (mp4) files, which should be set as environment variables `$SRC` and `$SRC2`
@@ -9,7 +13,7 @@ gst-launch-1.0   \
     filesrc location="$SRC2" ! \
     decodebin ! videoconvert ! \
     videoscale ! video/x-raw,width=640,height=360 ! \
-    videomixer name=mix sink_0::alpha=1 sink_1::alpha=1 !   \
+    compositor name=mix sink_0::alpha=1 sink_1::alpha=1 !   \
     videoconvert ! autovideosink \
     filesrc location="$SRC" ! \
     decodebin ! videoconvert ! \
@@ -24,7 +28,7 @@ gst-launch-1.0   \
     filesrc location="$SRC2" ! \
     decodebin ! videoconvert ! \
     videoscale ! video/x-raw,width=640,height=360 ! \
-    videomixer name=mix sink_0::alpha=1 sink_1::alpha=1 !   \
+    compositor name=mix sink_0::alpha=1 sink_1::alpha=1 !   \
     videoconvert ! autovideosink \
     filesrc location="$SRC" ! \
     decodebin ! videoconvert ! \
@@ -40,7 +44,7 @@ gst-launch-1.0   \
     filesrc location="$SRC2" ! \
     decodebin ! videoconvert ! \
     videoscale ! video/x-raw,width=640,height=360 ! \
-    videomixer name=mix sink_0::alpha=1 sink_1::alpha=1 sink_1::xpos=50 sink_1::ypos=50 !   \
+    compositor name=mix sink_0::alpha=1 sink_1::alpha=1 sink_1::xpos=50 sink_1::ypos=50 !   \
     videoconvert ! autovideosink \
     filesrc location="$SRC" ! \
     decodebin ! videoconvert ! \
@@ -48,3 +52,25 @@ gst-launch-1.0   \
     mix.
 ```
 
+---
+
+Add audio by demuxing the inputs so it can be handled separately. This example does so on the first source (rather than mixing the two together):
+
+```
+gst-launch-1.0   \
+    filesrc location="$SRC" ! \
+    qtdemux name=demux  demux.audio_0 ! queue ! decodebin ! audioconvert ! audioresample ! \
+    autoaudiosink \
+    demux.video_0 ! queue ! \
+    decodebin ! videoconvert ! \
+    videoscale ! video/x-raw,width=640,height=360 ! \
+    compositor name=mix sink_0::alpha=1 sink_1::alpha=1 sink_1::xpos=50 sink_1::ypos=50 !   \
+    videoconvert ! autovideosink \
+    filesrc location="$SRC2" ! \
+    decodebin ! videoconvert ! \
+    videoscale ! video/x-raw,width=320,height=180! \
+    mix.
+```
+
+
+