Playing with C920 web camera via UDP to ODROID

[KenW6HHC]

Just a note that I am having some fun learning and testing how to use the Logitech C920 web camera on a Win7 notebook to send UDP packets over to an ODROID running express_server and shipping the DVB-S to the DATV-Express board. Charles G4GUO is my mentor and has patiently helped me capture my first transmitted video on Sunday.

The Win7 is running free vMix to control the video and GraphStudioNext to construct a graph with DirectShow filters that are configured into this graph to add the software MPEG2 encoding filters from MainConcepts (grabbed them off my Hauppauge CD-ROM). Finally, a small software program (also another filter) called MajorUPDsender runs on the Win7 notebook and sends the UDP packets via Wi-Fi to the IP address of my ODROID.


vMix manages the C920 video and GraphStudioNext allows MPEG2 encoding and aims the UDP packets to the Wi-Fi port

The ODROID U3 is running an express_server that captures the incoming Wi-Fi UDP packets that are sent by the ODROID to the DATV-Express board. The express_server code was written by G4GUO and needed to be compiled from source onto the ODROID. Note the normal DATV-Express GUI software is not be used at this point.


The express_server software is installed and runs on ODROID. It captures the incoming Wi-Fi UDP packets and sends the Transport Stream to DATV-Express board

The DVB-S Standard Definition (SD) video was then displayed on my SatLink analyzer. The best part may be that there is no Hauppauge video-capture module involved with this testing set-up.

Still a lot of work that I need to do in order to clean up the somewhat-jerky video and some latency issues. But it works and it is fun.

73…de Ken W6HHC

[N6GKJ]

Hello Ken,

Are you able to capture and encode audio as well??

Ron,
N6GKJ

[KenW6HHC]

Hi Ron N6GKJ,

Yes, If you look in the lower-left of the GraphStudioNext graph below, you will see a filter for vMix audio,



For my current testing, I have configured the vMix audio filter to use the audio from my Logitech earphone/mike to become the input to vMix audio. I found if I used the audio from the web camera...I had audio feedback with my Win7 notebook speakers inside vMix.

73...de Ken W6HHC

[KenW6HHC]

Using the comments of Jean-Pierre F6DZP on a different forum (Yahoo DigitalATV group), I have eliminated my use of the vMix video mixing/editing software in my UDP testing set-up and also switched to my older Logitech C615 camera that does NOT natively stream H.264 video and therefore does not immediately require some extra decode latency. It turns out the vMix was only suggested by Charles G4GUO to add “call letters overlay” to the camera video. Also, there really is a tripod mounting point on the C615 webcam…it was just covered up with a small rubber insert.


GraphStudioNext graph for using C615 webcam filter

In the new graph shown above, the Logitech C615 video source filter is used and also the Logitech USB headset/mike audio source filter is used. The filter called MajorUDP-sender aims UDP packets via WiFi from my Win7 notebook to the express_server running on ODROID U3. The video latency I am seeing now is much less than the long latency I had encountered earlier with my set-up for C920/H.264 webcam….and my latency may now be less than what I normally encounter with my Hauppauge video-capture unit?

I need to still sort out some video freezing issues that eventually occur at the receiver (buffering overflow on ODROID??) But UDP with DATV-Express board basically works and it is fun.

73…de Ken W6HHC