JScrCap screen capture utility for both FMS and Wowza Media Server

I have been evaluating JScrCap for a while now and finally i got something to write about. I got it working with both FMS and Wowza.  There are few pros and cons I am detailing below in the article.

Quality and memory usage is pretty good compare to the VH Capture which, we (flash media community) were used to use for screen-sharing applications.

You just have to put the JScrCap bundle on any web-server and use the JScrCap as an Applet in html page to start with. Just call the web page and it will prompt the client that there is an applet you want to run it or not. As soon as user clicks the run he is ready to share his screen through Flash media server or Wowza Media server.

FMS (Flash Media Server)

  1. You can’t use the default code i.e. SVC1 and also free codec used for screencapture with JScrCap utility as FMS doesn’t recognize this codec. Actually FMS  drops connection after first frame. Access log shows 419 x-status code, which means “License to receive screen sharing video failed”See more info or feedback from Flash community as Steafen puts in his blog.
  2. You can only use H264 codec for screencapture which does have licensing limitations.
  3. Using H264 you can’t reocrd flv file on server you can only create mp4 files. So in case you want to use FMS for screensharing using JScrCap and want to record the stream on server as well you have to make sure you record the incoming stream as mp4 stream not flv. Following is the error i see in log file if I try to record the h264 data as flv “2009-07-09 15:07:30 7180 (w)2611179 Warning from libflv.dll: Recording H264 to FLV is unsupported, tried in FLV :
    F:\RnD\FlashCom\FlashComm Applications\livestreamrecord\streams\_definst_\livestream.flv.
    2009-07-09 15:09:03 7180 (e)2601163 Failed to record F:\RnD\FlashCom\FlashComm Applications\livestreamrecord\streams\_definst_\livestream, no space left on device -“

  4. You can record metadata in mp4 file using FMS.

Wowza Media Server

  1. You can use both codec i.e. default one SVC1 or H264 for screencapture.
  2. You can record flv or mp4 files using h264 codec in Wowza.
  3. Wowza doesn’t record data in mp4 stream. So if you want to access data across in recorded stream make sure you only record the stream as flv.
  4. JScrCap sent mouse coordinates data as onMouseData so in case you are using Wowza with JScrCap you have to listen on onMouseData on Netstream object. This was an update Vladimir done recently on request as earlier the way data was being sent across using JScrCap was only recognized by FMS not Wowza. It was pointed to me by Charlie that the wowza doesn’t record the metadata the way JScrCap is sending so he suggested the way it should be and thankfully Vladimir did it very quickly.
  5. The other major benefit of using Wowza is that you can use EC2 instance of wowza which has very less cost compared to the upfront cost you have to pay to get FMS.

I tested it on Windows and Mac and it worked fine. I think any user’s platform which will be able to run java applet through JVM etc. can have screensharing working through his system.

The other important thing I noticed in JScrcap notes is that SVC1 – works on all platforms, H264 – works only on Windows and MacOSX. So as FMS can only interpret h264 stream not SVC1  that means we wont be able to use screensharing on Linux machines with FMS we have to use Wowza there as it does recognize SVC1 compressed stream.

Please post your views regarding this article or if there is anything missing I can update it here.