Portsdown Video Sources

The video encoders on the Portsdown transmitter need specific configuiration for each video device. Information about some of these devices has been collated on this page. The exact model of device can be found by using the Linux command lsusb and checking the manufacturer and device IDs - each are 4-digit hex numbers.

The information needed to configure the cameras for the Portsdown can be gleaned from the following commands:

v4l2-ctl --list-devices
v4l2-ctl -d /dev/video1 --list-formats-ext
arecord -l
arecord -f S16_LE -c 2 -r 60000 -D hw:1,0 -d 5 testS16_LE.wav

Then trial and error is required to fine-tune the response.

WebCams

Logitech C920 - Old Version

Response to lsusb:

ID 046d:082d Logitech, Inc. HD Pro Webcam C920

This version of the C920 includes a very capable hardware H264 encoder, which is not included in the newer version. This camera is supported by both the Portsdown 2020 and the Portsdown 4. The responses to the commands above are listed here: Media:C920_Old.pdf

Logitech C920 - New Version

Response to lsusb:

ID 046d:0892 Logitech, Inc. OrbiCam

This newer version of the C920 has different electronics without the H264 hardware encoder included. The reponses to the commands above are listed here: File:C920_New.pdf

Logitech C170

The Logitech C170 is a basic 640x480 webcam with single channel (48k) audio. The parameters are here: File:C170.pdf

Format Selection in ffmpeg

To select the camera output format to be used as an input by ffmpeg, one of the 3 following parameter values can be used:

-f v4l2 -input_format h264
-f v4l2 -input_format yuyv422
-f v4l2 -input_format mjpeg