Interlacing lines on movement

[tibetfreedom]

Hi I am getting lines when there is movement but not when there is no movement..
I have searched the forums and looked and added two monitors set to "None:" as we have an 8 port bbtv card and six camera's.
It's not critical but would be nice to remove these lines …
Thanks.

[tibetfreedom]

Any takers for this ? I'm sure it's quite simple….

[zoneminder]

Interlacing is caused because a frame can be made up of two captured frames one making up the odd lines and one the even. They are captured at different times so any movement shows up. The new version 1.24.3 allows you to disable this behaviour in most cases.

[tibetfreedom]

Interlacing is caused because a frame can be made up of two captured frames one making up the odd lines and one the even. They are captured at different times so any movement shows up. The new version 1.24.3 allows you to disable this behaviour in most cases.

Oh How ?
I suppose I expected smooth movement like any TV camara… ?
How can I stop this behaviour ?
are there any pitfalls to stopping it ?

[zoneminder]

Actually most TV is interlaced (at least it used to be) so you would see this but in continuously updated video it isn't so obvious, plus generally the faster frame rate is enough to hide it and minimise it's effect.

The options available are basically, to just capture the odd (or even) frames, or both but separately rather than both interlaced. The option is in Options->Config->V4L2_CAPTURE_FIELDS. This is the help text for that option

The Video4Linux2 standard allows finer control of interlacing than the previous version. This option allows finer control over how the system handle interlacing in general for V4L2 devices. The possible values are described at http://v4l2spec.bytesex.org/spec/x6386.htm#V4L2-FIELD and the default value of 0 allows the driver to decide for itself. This will often result in interlaced images.
The most useful other values are 2 (top, or 3 for bottom) which prevent interlacing by only capturing one field (or set of scanlines), or 7 which captures both fields but in separate images. This latter option can increase frame rates but with the possibility that alternate frames are one scanline offset from each other so may appear to move up and down slightly.
Note that preventing interlacing when capturing large image sizes may not actually increase the information content as often the maximum size of single field, non-interlaced, images may be fairly small and the image is just enlarged in the application.

This all assumes you are using connected analog cameras. If you get interlacing with netcams then it's not really anything that ZM can do anything about at the moment.