Output Video from Snowmix
Minimal Configuration for output
For snowmix to send the mixed video frames to output, Snowmix must have at least a minmial configuration similar to the configuration shown below.
port 9999
geometry 1024 576 BGRA
frame rate 24
socket /tmp/mixer1
feed idle 0 1
stack 0
The first line tells Snowmix to listen for command and control connections on port 9999. The second line sets the system geometry, the geometry of the mixer to 1024x576 and use the internal pixel format BGRA. The third line sets the mixer frame rate to 24 fps. The fourth line instructs Snowmix to use the socket /tmp/mixer1 for communicating with an external program using a GStreamer shmsrc interface for getting the mixed frames from Snowmix. Obviously your system must support shared memory. The fifth line sets the idle time for feed 0 to 1 frame. The fifth line instructs Snowmix to stack Snowmix's system frame as the bottom frame of every frame Snowmix will output. Feed 0, or the system frame provides by default a black background as the basis for the entire mixed frame unless configured for something different.
Obviously you will for most cases also want to add inputs and display them as shown in the Snowmix GStreamer Input examples.
Getting Mixed Frames from Snowmix
The main loop of Snowmix, the mixing of video frames, is skipped by a running Snowmix session until data is read on its output interface. No need to mix a frame that is never read. The output interface of Snowmix is compatible with GStreamer shared memory module shmsrc. The examples below shows how GStreamer can be used to read frames from Snowmix.
The first example will display the mixed frame on the local machine running Snowmix assuming it has a graphic display. It has been tested with GStreamer 0.10, 1.0.0 through 1.5.2 although GStreamer 0.10 is no longer official supported.
#!/bin/sh
# Deliver mixer1 output to screen.
# The geometry and framerate are from your system settings in Snowmix
width=1024
height=576
framerate='24/1'
which gst-launch-1.0 2>/dev/null 1>&2
if [ $? -eq 0 ] ; then
gstlaunch=gst-launch-1.0
VIDEOCONVERT=videoconvert
MIXERFORMAT='video/x-raw, format=BGRA, pixel-aspect-ratio=1/1, interlace-mode=progressive'
else
gstlaunch=gst-launch-0.10
VIDEOCONVERT=ffmpegcolorspace
MIXERFORMAT="video/x-raw-rgb,bpp=32,depth=32,endianness=4321,red_mask=65280,green_mask=16711680"
MIXERFORMAT="$MIXERFORMAT,blue_mask=-16777216,pixel-aspect-ratio=1/1,interlaced=false"
fi
$gstlaunch -v \
shmsrc socket-path=/tmp/mixer1 do-timestamp=true is-live=true !\
$MIXERFORMAT", framerate=$framerate, width=$width, height=$height" !\
queue !\
$VIDEOCONVERT !\
queue !\
autovideosink
If the autovideosink fails for your system depending on your setup, then try one of the other videosinks such as xvimagesink, ximagesink, glimagesink etc. There are many to choose from depending on your system.
Stream H.264 Video as RTP over UDP from Snowmix
The example below encodes the output from Snowmix with x264 and send it to another host using RTP over UDP.
#!/bin/bash
# The geometry and frame rate are from your system settings in Snowmix
width=1024
height=576
framerate='24/1'
which gst-launch-1.0 2>/dev/null 1>&2
if [ $? -eq 0 ] ; then
gstlaunch=gst-launch-1.0
VIDEOCONVERT=videoconvert
MIXERFORMAT='video/x-raw, format=BGRA, pixel-aspect-ratio=1/1, interlace-mode=progressive'
else
gstlaunch=gst-launch-0.10
VIDEOCONVERT=ffmpegcolorspace
MIXERFORMAT="video/x-raw-rgb,bpp=32,depth=32,endianness=4321,red_mask=65280,green_mask=16711680"
MIXERFORMAT="$MIXERFORMAT,blue_mask=-16777216,pixel-aspect-ratio=1/1,interlaced=false"
fi
SRC='shmsrc socket-path=/tmp/mixer1 do-timestamp=true is-live=true'
X264SETTINGS='bitrate=3000 tune=zerolatency speed-preset=5'
$gstlaunch -v \
$SRC !\
$MIXERFORMAT", framerate=$framerate, width=$width, height=$height" !\
queue !\
$VIDEOCONVERT !\
queue !\
x264enc $X264SETTINGS !\
h264parse !\
rtph264pay !\
queue !\
udpsink clients=192.168.0.15:4012 sync=true
Obviously you will have to set the IP address and port to match your requirements. If the clients option of udpsink gives you any problem, then try this:
... ! queue ! udpsink host=192.168.0.15 port=4012 sync=true
Instead of the udpsink your could also replace it with a tcp server like this:
... ! queue ! tcpserversink host=0.0.0.0 port=4012 sync-method=2 recover-policy=keyframe
For more examples on outputting from Snowmix, please see the following scripts in the $SNOWMIX/scripts directory:
| Script Name | Function |
| output2dummy | reads video frames from Snowmix and discards them. |
| output2screen | reads video frames from Snowmix and displays them locally on screen. |
| output2file | reads video frames from Snowmix, encodes them and saves encoded stream in a file. |
| output2rtp | reads video frames from Snowmix, encodes them and stream them as RTP packets over the network. |
| av_output2dummy | as output2dummy, but also reads audio from Snowmix. |
| av_output2screen | as output2screen, bus also reads audio and plays audio. |
| av_output2tcpserver | reads video frames and audio, encodes video and audio and makes the muxed stream available on a tcp server. |
