WebRTC can't get a video feed from a USB input device (readyState goes to ended)

The specs on Media Capture Streams state that during the life-cycle of a MediaStreamTrack the live state may be replaced by zero-information-content if the MST has either been "muted" or "disabled".This will result in rendering black frames.

In other words media can only flow from the source if the MST is both, unmuted and enabled.

The muted/unmuted state reflects if the source provides any media.

The enabled/disabled state determines whether the track outputs media.

Make sure that no other application is using your source device. In your case the StarTrack converter. Close all other applications that might gain access to your capture device while you try to getUserMedia in the browser.

Visit this Working Draft for more information on MST life-cycle and flow.

Another problem may be that your device does not provide media that meets the constraints present on your media track. Your device is capable of delivering NTSC and PAL video signals. So try to adjust the constraints for getUserMedia e.g. for PAL signal like so:

{   audio: false,  video: {    mandatory: {      maxWidth: 768,      maxHeight: 576,      maxAspectRatio: 1.333,      maxFrameRate: 25  }}

Hope that helps somehow.