VLC HowTo/Make a mosaic
Contents
VLC mosaic howto
This is a small example about how to use VLC to create a mosaic. What we basically want is a video mosaic mixing 3 video channels (channels 1, 2 and 3) on a background image (background_image.uyvy) and streaming the resulting video on the network. Note that we will also be streaming the 3 sound tracks from channels 1, 2 and 3 in the same mpeg-ts stream.
Step 0
Read the VLC streaming howto (chapters 3 and 5 concerning command line and vlm usage in VLC) : http://videolan.org/doc/
Step 1
Get VLC 0.8.2-test1 or newer and install it on your computer. (you need an ffmpeg version older than 28/04/2005. Compatibility with newer versions will be fixed)
Step 2
You now have to get a background image. This image needs to be in the uyvy format. The conversion of any format to uyvy can be acheived using the programs given by the imagemagick package in debian linux.
Take any image (image.ext) and convert it to the uyvy format. The source and destination image sizes are necessary.
convert -size 360x288 image.ext -resize 360x288 image.uyvy
You can then test the resulting image :
display -size 360x288 image.uyvy
You can also test it with VLC to see if it displays locally :
./vlc --sout-switcher-files=videolan.uyvy --sout-switcher-sizes=360x288 --sout-switcher-command=1 --ttl 12 --sout "#switcher:display" fake:
Step 3
You now need to configure VLC to get the 3 source streams and blend them on the background image.
The vlm configuration file looks like :
new channel1 broadcast enabled
setup channel1 input udp://@239.255.2.60:1234
setup channel1 output #duplicate{dst=mosaic-bridge{id=1,height=144,width=180},select=video,dst=bridge-out{id=1},select=audio}
new channel2 broadcast enabled
setup channel2 input udp://@239.255.10.200:1234
setup channel2 output #duplicate{dst=mosaic-bridge{id=2,height=144,width=180},select=video,dst=bridge-out{id=2},select=audio}
new channel3 broadcast enabled
setup channel3 input udp://@239.255.6.9:1234
setup channel3 output #duplicate{dst=mosaic-bridge{id=3,height=144,width=180},select=video,dst=bridge-out{id=3},select=audio}
new background broadcast enabled
setup background input fake:
setup background output #switcher{files=/home/via/videolan/background_image.uyvy,sizes=360x288,command=1}:transcode{sfilter=mosaic,vcodec=mp2v,vb=10000,scale=1}:bridge-in{delay=400,id-offset=100}:standard{access=udp,mux=ts,url=239.255.12.42,sap,name="mosaic"}
control background play
control channel1 play
control channel2 play
control channel3 play
Note that the source streams are network streams, which is likely to be the case if you're considering doing a mosaic.
Step 4
And now, the right command to launch vlc :
./vlc --color -I telnet --vlm-conf ../mosaic.vlm.conf --ttl 12 \ --mosaic-width 360 --mosaic-height 288 --udp-caching 800 \ --mosaic-keep-picture --mosaic-rows 2 --mosaic-cols 2 \ --mosaic-position 1 --mosaic-order 1,2,3
Appendix
Mosaic video sub filter
The full set of mosaic commands is :
Mosaic video sub filter
--mosaic-alpha <integer> Alpha blending
Alpha blending (0 -> 255). Default is 255
--mosaic-height <integer> Height in pixels
Height in pixels
--mosaic-width <integer> Width in pixels
Width in pixels
--mosaic-align {0 (Center), 1 (Left), 2 (Right), 4 (Top), 8 (Bottom), 5 (Top-Left), 6 (Top-Right), 9 (Bottom-Left), 10 (Bottom-Right)}
Mosaic alignment
Mosaic alignment
--mosaic-xoffset <integer> Top left corner x coordinate
Top left corner x coordinate
--mosaic-yoffset <integer> Top left corner y coordinate
Top left corner y coordinate
--mosaic-vborder <integer> Vertical border width in pixels
Vertical border width in pixels
--mosaic-hborder <integer> Horizontal border width in pixels
Horizontal border width in pixels
--mosaic-position {0 (auto), 1 (fixed)}
Positioning method
Positioning method. auto : automatically
choose the best number of rows and columns.
fixed : use the user-defined number of rows
and columns.
--mosaic-rows <integer> Number of rows
Number of rows
--mosaic-cols <integer> Number of columns
Number of columns
--mosaic-keep-aspect-ratio, --no-mosaic-keep-aspect-ratio
Keep aspect ratio when resizing (default
disabled)
Keep aspect ratio when resizing (default
disabled)
--mosaic-keep-picture, --no-mosaic-keep-picture
Keep original size (default disabled)
Keep original size (default disabled)
--mosaic-order <string> Order as a comma separated list of
picture-id(s)
Order as a comma separated list of
picture-id(s)
--mosaic-delay <integer> Delay
Pictures coming from the picture video
outputs will be delayed accordingly (in
milliseconds). For high values you will need
to raise file-caching and others.
Mosaic bridge stream output
The full set of mosaic bridge stream output commands is :
Mosaic bridge stream output
--sout-mosaic-bridge-id <string>
ID
Specify an identifier string for this
subpicture
--sout-mosaic-bridge-width <integer>
Video width
Allows you to specify the output video width.
--sout-mosaic-bridge-height <integer>
Video height
Allows you to specify the output video height.
Bridge stream output
The full set of bridge stream output commands is :
Bridge stream output
--sout-bridge-out-id <integer>
ID
Specify an identifier integer for this
elementary stream
--sout-bridge-in-delay <integer>
Delay
Pictures coming from the picture video
outputs will be delayed accordingly (in
milliseconds, >= 100 ms). For high values you
will need to raise file-caching and others.
--sout-bridge-in-id-offset <integer>
ID Offset
Offset to add to the stream IDs specified in
bridge_out to obtain the stream IDs bridge_in
will register.
