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Record video to SD card

Discussion in 'General Electronics Discussion' started by Somethingrandom, Mar 3, 2014.

  1. Somethingrandom

    Somethingrandom

    22
    2
    Jan 20, 2014
    Hi people, Im looking for some way of recording video to some type of storage device, for example a nannycam. I would like to work with a cctv camera with the RCA style connectors and write to an SD card perhaps. I know numerous spy cams etc exists on ebay but I am interested in this for educational purposes and dont want to just go out and buy something. Can anyone refer me to some ICs that are made for this purpose( writing to an SD card, or decoding output from the CCTV camera etc) or perhaps sling me some useful links? Would be great thanks!
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,416
    1,925
    Nov 17, 2011
    There's probably not a single IC that does the job.
    You need circuitry to extract the timing from the analog signal.
    You need to digitize the analog signal from the camera with an A/D converter.
    The data rate and amount of data of the digitized signal is probably much too high. You need to compress it (e.g. MPEG encoding as used on DVDs).
    You need a controller to store the data to an SD card.

    You can circumvent the first few issues by using a camera that has a digital interface (USB, Ethernet) and delivers already digitized and compressed data. You still need a controller to store the data on an SD card. Any PC can do this, or use a controller board like e.g. the beaglebone , RaspberryPi or similar.
     
  3. shumifan50

    shumifan50

    548
    56
    Jan 16, 2014
    You will have to be a bit more specific as to how low-level you want to go. Also different cameras have different capabilities: some stream, some do MJPEG (Motion JPEG), requiring different levels of complexity to decode and record.
    So:
    Hardware requirements
    1. Do you want to build your own microcontroller board and develop your own software?
    2. Do you want to work at the chip level or would the use of interface boards be within your requirements.
    3. Have you worked with open source software (modify, build, install)?

    Software requirements
    1. Do you need libraries to interface or is part of the learning actually writing the code to drive the interfaces.
    2. Do you want to use an operating system, like Linux, or develop without an operating system?

    Experience
    1. What is your experience with electronics: design, build, test, program boards.
    2. What is your software development experience? Have you developed for micro controllers with and/or without operating systems.
    3. Have you written software interfacing at the chip level?
    4. Have you written controller software interfacing with libraries?
    5. Do you have the facilities (scope, digital multimeter etc) to debug hardware and software?

    You will be working with 2 interfaces that are very timing dependent. Even the Raspberry Pi still battles with flash writing and fails every so often if the SD card is not a perfect match for the software.

    Some Microchip PICs have inbuilt support for USB and flash and free libraries to drive them, but I have never used them and don't know how reliable they are. However, since I have not needed them, I am not 100% sure, but don't believe they have interface hardware/software for video streaming or compression/decompression.
     
    Last edited: Mar 3, 2014
  4. Somethingrandom

    Somethingrandom

    22
    2
    Jan 20, 2014
    The analogue to digital conversion and compression handling all sound rather daunting to me. That being the case, I will look into a webcam/PI solution, I haven't worked with PI before, sounds like a good excuse. Cheers guys.
     
  5. shumifan50

    shumifan50

    548
    56
    Jan 16, 2014
    There are many IP cams available that support wifi and hard-wiring at comparatively low cost. These will be the easiest to use as a lot of work is done in the camera firmware, simplifying the host code requirements.
     
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