In my attempt to stream live video to my iPhone I ran into an issue with the USB QuickCam I have. Instead of fighting the problem I decided to turn to the iSight camera on a macbook but I quickly found that there isn't a great way to get the video stream to another machine. The best way that I have found to stream from the iSight to a second machine is to use a combination of QuickTime Broadcaster and VLC. In this post I detail how I got it set up and working.

Step 1: Install QuickTime Broadcaster

The first step is to install QuickTime Broadcaster. It doesn't have a lot of requirements so it should work on most macs. The QuickTime Broadcaster will be the source of the video and the destination of the video in my case is a second machine with VLC installed on it although you could run VLC on the source machine if you wanted to.

An important note at this point is to make sure the destination machine doesn't have a firewall turned on or if it does that it isn't blocking ports 5432 and 5434.

Step 2: Configure QuickTime Broadcaster for Streaming

Navigate to the Applications folder and launch QuickTime broadcaster. Click on the network tab and select "Custom" from the "Preset" list. For "Transmission" select the "Manual Unicast" option. The "Address" field contains the IP for your target machine, the one that you are streaming to. When you are finished, your settings should look something like this:

Now the configuration is ready and it is time to create an export for use in VLC. To export go to File -> Export -> SDP menu option. For this example I'm calling the file stream01.sdp.

You should transfer this file to the machine you are going to run VLC on at this point. If you are interested you can actually view the contents of the SDP file. Here is the one generated for me from the above:

v=0
o=- 0 3702455757 IN IP4 127.0.0.0
s=QuickTime
t=0 0
a=range:npt=now-
a=isma-compliance:2,2.0,2
m=audio 5432 RTP/AVP 96
c=IN IP4 192.168.132.100
b=AS:125
a=rtpmap:96 mpeg4-generic/44100/2
a=fmtp:96 profile-level-id=15;mode=AAC-hbr;sizelength=13;indexlength=3;indexdeltalength=3;config=1210
a=mpeg4-esid:101
m=video 5434 RTP/AVP 97
c=IN IP4 192.168.132.100
b=AS:1372
a=rtpmap:97 H264/90000
a=fmtp:97 packetization-mode=1;profile-level-id=4D401E;sprop-parameter-sets=J01AHqkYFAe2ANQYBBrbCte98BA=,KN4JF6A=
a=mpeg4-esid:201
a=cliprect:0,0,480,640
a=framesize:97 640-480

Step 3: Play the Video Stream with VLC

Once the SDP file is on the destination machine you can start VLC and open it. In VLC go to File -> Open File then select the SDP file that was exported earlier.

VLC is now ready to stream from QuickTime Broadcaster. In QuickTime Broadcaster click the Broadcast button and then in VLC click the play button. At this point you should start seeing the stream in VLC. The order you start broadcasting between QuickTime Broadcaster and VLC doesn't seem to matter. There were a few times that I had VLC start for a second then freeze but I was using a wireless network so I'll blame that for the freezes. In general it worked well once it was all set up.

You can start VLC from the command line and point it directly to the stream file if you want. To do that use this command:

vlc stream01.sdp

or if you want fancy logging:

vlc -vvv --color --file-logging --logfile vlc-log.html --logmode html stream01.sdp

Step 4: VLC Streaming

This is actually what I would call re-streaming since my need is to get the iSight stream to FFMpeg. In the perfect world I would be able to stream directly from QuickTime Broadcaster to FFMpeg but the limitations of QuickTime Broadcaster don't allow that to happen, at least from what I could find.

To re-stream the iSight stream follow these steps:

1. Go to Media -> Streaming

   

   Enter the SDP file in the file window and hit the Stream button.

2. After you click the Stream button a window will pop up where you have the option to select a Destination:

   

   Select "Display locally" if you want to see the video as it is re-streamed.

   Select HTTP from the "New destination" drop down list and click the Add button. I have picked HTTP here because it is what works the best for me but there are other options you can use if you want to try different streaming protocols. I was able to leave the defaults as they were for the HTTP stream.

3. Select a transcoding profile. Here I've selected the "Video – Theora + Vorbis (OGG)" profile for streaming. It seems to work the best for me:

   

   Click the Stream button at the bottom to start streaming.

4. Test the stream with something like mplayer or ffplay. Because I'm using HTTP to do the stream I can run the following command to test:

   mplayer http://192.168.132.100:8080/
   

   Just as the playback can be done from the command line the re-streaming can too:

   vlc stream01.sdp --sout '#transcode{vcodec=theo,vb=800,scale=1,acodec=vorb,ab=128,channels=2,samplerate=44100}:duplicate{dst=std{access=http,mux=ogg,dst=0.0.0.0:8080},dst=display}'
   

   If you want to drop the local display:

   vlc stream01.sdp --sout '#transcode{vcodec=theo,vb=800,scale=1,acodec=vorb,ab=128,channels=2,samplerate=44100}:duplicate{dst=std{access=http,mux=ogg,dst=0.0.0.0:8080}}'