video logging

ocean bill

I have a newbie question: How do you log video to a sd card? More specifically, I need to log color video from a lipstick camera or board camera directly to an sd card, using the bare minimum of hardware. I do not need an LCD screen or other features. Small component size is critical, including battery(s). This will be installed in an underwater housing for tagging marine turtles, seals, etc. I currently use a micro Digital Video Recorder (DVR) with MPEG4 compression, but the unit includes a video screen and unecessary features, making the unit bulky. The intent is to install all the electronics, including camera in a approximately one inch I.D. tube housing. Can you recommend the essential components?
Bill

Mike Green

If you need full resolution video, I think you're better off with a DVR. You could try something like a Gumstix embedded Linux processor which could handle a tiny webcam for a camera and do the compression and writing to the SD card. I don't think you'll get much battery life. The power needed to run a fast enough processor will drain a battery pretty fast. If you only need individual still pictures and you don't need more than say QVGA pictures, there are some cameras that do their own JPEG compression and transfer the file to a controller. You would need an SX or Propeller for the speed to do the download and transfer to an SD card or possibly use something like Parallax's memory stick datalogger to transfer the images to a USB flash drive.

ocean bill

Thanks Mike. However, the DVR is too large. Does the propeller have a video function of some sort? I'm having trouble finding what features the propeller has.

I need to run video, not still pictures. I guess what I'm asking is what are the minimun components (Parallax or not) I need to go from a video camera to Sd card? Otherwords, a DVR without the LCD, control buttons, playback features, etc, etc. The video does not neccessarly have to be full resolution.

Thanks,
Bill

Mike Green

The Propeller has a video generator on the chip that makes the production of video output (or VGA output) easier and very practical. There's no corresponding video input hardware. Several people have done video input sampling and Viewport 2 shows how B & W at limited resolution can be transmitted over a serial link.

The current SD card routines were intended to provide basic functionality and are not optimized for speed. They use a slower SD card I/O mode than is available. I don't know how fast a frame rate can be handled. You'd have to do some experimenting.

Basically, there's no "ready to go" functionality for recording video using the Propeller for a controller. It's not clear that the Propeller could do the job although it might with some careful constraints and tight assembly language programming.

I still think the easiest route would be to use a USB webcam and an embedded Linux processor with SD card support, like the Gumstix. I'm not familiar enough with Linux video programs, but I suspect you could find something that would work doing on-the-fly compression to a file.

ocean bill

I took a look at the Gumstix. My knoweledge of this stuff is very limited, but Gumstix looks promising. Thanks for the suggestion.

BobN

I'm not sure if this would be appropriate to put in the forum since it is not a Parallax product but take a look at:

http://www.electronics123.com/s.nl/it.A/id.2566/.f

- Bob -

Mike Green

Other than being too big, this looks like the sort of thing you want. Do note the power consumption. Any time you start doing video processing, it will take more power than you think. You're talking about processing a lot of data very quickly.

ocean bill

Thanks BoB. The unit is a little large and frame rate a bit slow, however, this put me on a new search path for similar units with 30 frames per second.