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Saving DV data to external memory from EVMDM365 ?

Jinh
Expert 2315 points

I am looking for a way to save the raw captured and somewhat modified UYVY video data on my evaluation board to external memory which could either be a big SD card or out over the USB or Ethernet.  The data is not compressed and recordings would probably be a maximum of about 25 minutes but usually much shorter.  This is to find a way of not playing the composite output to a DVD recorder to save my data 'n mpeg2 format but to save the digital data directly from the dm365.  Please point me to any demo's I can look at or any suggestions on how to do this without too many extra stuff.

I am thinking around something like my old Sony video camera that could stream DV data to my PC via FireWire or USB and then some standard software to record it to harddisk.  What protocols are involved in this and where can I find documentation on it if this is a way to go?

Thanks for any help, Jinh T.

  • 0
    TI__Mastermind 19985 points

    Hi,

    Jinh said:
    I am thinking around something like my old Sony video camera that could stream DV data to my PC via FireWire or USB and then some standard software to record it to harddisk.  What protocols are involved in this and where can I find documentation on it if this is a way to go?

    In earlier video cameras, they generally did not use any standard protocol and had their own implementation of DV data transfer. Now there are standards like UVC over USB that is supported by most of the USB hosts on PC operating systems. I can recommend using any such UVC utility. DM36x LSP already has support for UVC. The problem though would be that the bandwidth for USB would be limited. I did not clearly understand the resolution that you are looking to save. If it is anything around a CIF (or at max VGA) resolution, raw YUV data at 30fps can still be recorded safely over USB. But more than that, we will start seeing problems or frame drops. The other option is encode as JPEG and send over USB or Firewire. It would still be lower bandwidth than raw data.

    Do you need real time data saving?

    Regards,

    Anshuman

    PS: Please mark this post as verified, if you think it has answered your question. Thanks.

  • 0 in reply to Anshuman Saxena
    Expert 2315 points

    Hi Anshuman,

    I am working with PAL-I video and because we are using the interlaced data split into field giving us an effective rate of 50Hz to better our performance, we do not want to do compression, lossy compression for that matter, so if we can save the "raw" data realtime it would be good but if lossless codec (I assume this would probably be the way to go to put it through mpeg2 encoder?) is used it could also be an option but we want to save it realtime.  If you refer to CIF going fine over USB, will 4CIF (704x576) which is probably what my PAL (D1 ?) is also be able to be streamed or is FireWire bandwidths necessary?  What would be the best that I will be able to achieve with my EVMDM365 board?

    I will investigate the UVC also. Thanks, Jinh T.

  • 0 in reply to Jinh
    TI__Mastermind 19985 points

    Hi,

    CIF to 4CIF would need four times bandwidth :)

    From my experience it should be possible to do a 4CIF 16-bit per pixel data over USB also, but there might always be a risk of dropping frames if there are other things on the system.

    Regards,

    Anshuman

    PS: Please mark this post as verified if you think it has answered your questions. Thanks.