Interlaced Videos and Images

Question

I have a BT878 Decoder, two cams attached and third cam via Network, controlled by motion. All running on Linux SuSE 9.2, no probs so far, except with interlaced images.

Interlacing does not occur on a constant basis but seems to swap between the two cams attached to the BT878 device. And it seems to be independent from any motion detection (i.e. mo det is enabled on one cam only).

I've tryed to reduce almost everything to the min: framerate, resolution. I've increased roundrobin skip and increased roundrobin frames and vice versa.

No changes on the long run.

I'm pretty lost, not to say I'm getting nuts on this... Any Help out there?

Environment

Motion version:	3.2.3
ffmpeg version:	ffmpeg-cvs-20050813-certified-with-motion-3.2.2
Libraries:	ffmpeg
Server OS:	SuSE 9.2, 2.6.8-24.10

-- AxelAmthor - 20 Oct 2005

Answer

I've almost solved the problem by adding another card for 25€ in to that machine, preventing the round robin featur to switch between inputs on one card. The interlacing is almost gone, only on fast moving objects there's something like an "interlacing halo" around the object. I consider this to be not a motion problem. Bottomline, the initial problem may have something to do with the channel switching on low cost cards. The two cards in one machine run me into other probs, but that's another story (PCI, IRQ, hardware stuff ...)

-- AxelAmthor

Yes. Motion does not have any control of when a video card interlaces the pictures captured other than setting framerate and resolution.

Round Robin is not the ideal way to capture images. It is always best to have one BT878 chip per camera. Either by using multiple cheap TV cards (I have run with 3 once and that gave no problems) or by buying a capture card with 4 or 8 BT878 chips.

-- KennethLavrsen - 28 Oct 2005