Streaming video from built-in webcam

2009-02-15T14:35:03Z

86.152.162.24:

{{Midgard article}}

It is possible to use the N800 camera as a source of streaming video. This was originally described [https://maemo.org/community/wiki/howtostreamvideo/ here], but the referenced example has an error which prevents it working.

This note describes how to stream video from the platform to an RTP sink, for example the [https://maemo.org/community/wiki/howtostreamvideo/ vlc] media player.

First, you must install the '''gstreamer-tools''' package from the diablo repo on repository.maemo.org.

# On the N800, the following script will stream video from the camera. Here, 172.31.0.244 is the Linux box with VLC installed, and 172.31.0.245 is the N800. I call this script <tt>~/bin/rtpstream.sh</tt>. <tt><nowiki>#!/bin/sh</nowiki></tt> 
<tt>VPORT=5434</tt> <tt>APORT=5432</tt> <tt>HOST=${1:-172.31.0.244}</tt> 
<tt>gst-launch-0.10 v4l2src ! \</tt> <tt>video/x-raw-yuv,width=176,height=144,framerate=$fraction$15/1 ! \</tt> <tt>hantro4200enc stream-type=1 profile-and-level=1001 ! \</tt> <tt>video/x-h263,framerate=$fraction$15/1 ! rtph263ppay mtu=1438 ! \</tt> <tt>udpsink host=$HOST port=$VPORT dsppcmsrc ! queue ! \</tt> <tt>audio/x-raw-int,channels=1,rate=8000 ! mulawenc ! rtppcmupay mtu=1438 ! \</tt> udpsink host=$HOST port=$APORT
# On the Linux box, the sample .sdp file from [http://web.media.mit.edu/%7Elifton/snippets/n800_to_sl/ the original article], with the address of our VLC player, saved as a file i.e. <tt>/tmp/n800.sdp</tt> <tt>v=0</tt> <tt>o=- 37 614155991 IN IP4 127.0.0.0</tt> <tt>s=QuickTime</tt> <tt>t=0 0</tt> <tt>a=range:npt=now-</tt> <tt>m=audio 5432 RTP/AVP 0</tt> <tt>c=IN IP4 172.31.0.245</tt> <tt>b=AS:63</tt> <tt>m=video 5434 RTP/AVP 96</tt> <tt>c=IN IP4 172.31.0.245</tt> <tt>a=rtpmap:96 H263-2000/90000</tt> <tt>a=fmtp:96 </tt> <tt>a=cliprect:0,0,144,176</tt> a=framesize:96 176-144
# On the N800, pop out the camera and run: $ ~/bin/rtpstream.sh # assume on PATH, +x etc.
# On Linux box (note VLC runs on other platforms as well): $ vlc /tmp/n800.sdp
# Enjoy streaming video (and sound) from the N800.

Thanks to [http://web.media.mit.edu/%7Elifton/snippets/n800_to_sl/ Josh Lifton] for the original leg wor

On a N800, to make the image vertically flip automatically when the camera's pointing backwards (so it's not upside-down), change the source name from "v4l2src" to "gconfv4l2src".

To adjust the video encoding quality, have a look at the parameters described by entering "gst-inspect hantro4200enc" at a shell prompt. Setting the "bit-rate" parameter to its maximum (515) and the "profile-and-level" parameter to 1007 produces a much better quality image. Also, I suspect the "stream-type" parameter should be "5" (H263), not "1" (MPEG4 Video).

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Streaming video from built-in webcam