• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 97 subscribers
  • Views 342 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DM6446 vs DM6467

Helmut Forren
Mastermind 6805 points

Can someone please tell me if I understand correctly, of if I'm totally missing the boat...

Having done some prototype video analytics development with the DM6446, I discovered the DM6467 when I started looking into High-Definition video.  At first, I thought the choice of DM6446 vs DM6467 was one of standard- vs. high-definition.  I was thinking along the lines of number of pixels and processing power.

However, after reading through the DM6446 to DM6467 migration guide found at http://focus.ti.com/lit/an/spraaz3/spraaz3.pdf, I now realize that these two chips have substantially the same video analytics capability.  They both have roughly the same ability to do processing on 1280 x 1080 images.  (While the DM6467 does have a clock option that's 23% faster, 23% is not a big difference for my application.  The difference in 640x480 and 1280x1080 is 450% as many pixels, so 123% the speed means little.)

The biggest difference between them is ANALOG vs DIGITAL video I/O.  The DM6446 is geared toward analog video, with included DAC's.  The DM6467 is geared toward digital video, with no DAC's.  Now, depending on ones application, analog video is indeed more often associated with Standard-Definition video, while digital video is indeed more often associated with High-Definition video.  However, this is not always the case.

In my application, I have control over the system from top-to-bottom, so I'm not necessarily tied to the type of video interface used by a particular video source (camera) or video display (studio monitor or IP video).  My prototype video analytics on the DM6446 was already capable of doing 1280 x 960 (SXGA), which is very close in pixel resolution to HD (such as 1280 x 1080p).  (Frame rate was only a minor priority during prototyping, so I don't know if the embedded camera producing 960 lines was producing progressive or interlaced.  All I know is I was receiving full frames at 30fps (or maybe 29.97fps).)

Therefore, it seems to me, that I need to make a decision about analog vs digital, and use THAT as the deciding factor between using the DM6446 or DM6467.

Am I understanding?

Thanks,

Helmut

  • 0
    TI__Genius 14405 points

    You are basically correct.

    Quick comment though: There are multiple speedgrades for each devices. Depending on the speedgrade of the part you are getting, the performance increase varies. If you are comparing the 600MHz DM6446 against 1GHz DM6467, you might get over 50% the performance w/ the DM6467T. You should be able to approximate the performance incrase using the clock rate increase, but the actual performance increase will be less because DM6446 also has VICP which can help in video analytics application (the HDVICP on DM6467 won't be able to help at the moment).

    DM6467 will show much greater advantage when it comes to encoding and decoding.
    Video capability wise, DM6446 can also capture/display HD video w/ its CCDC/VENC repsectively, but the pixel clock is limited to 75MHz; with Dm6467T, your pixel clock can go up to 150MHz.

    BTW, 1280x1080P, what is that? 1280x720 or 1920x1080?

  • 0 in reply to Paul.Yin
    Mastermind 6805 points

    Paul,

    Regarding speed, I also saw MMACS in some table, and noticed it wasn't linear with clock rate.  (I figure that's million multiply and accumulate cycles per second.)

    Regarding 1280x1080p, it's a figment of my imagination... er, I actually meant 1920x1080p.  Also, I made that same mistake in comparing to 1280 x 960 (SXGA) in this post, so my statement about "very close" is wrong. 1920x1080=2M while 1280x960=1.2M.  There's almost a factor of two increase in number of pixels, and corresponding increase in horsepower need for video analytics algorithms that grow linearly with number of pixels.  

    Having just now deleted a bunch of written circular logic from this paragraph, I end up figuring I need...

    (A) the higher speed of the DM6467,

    (B) can deal with the more digital-oriented I/O, even if I need analog I/O (the Spectrum Digital HD1080P EVM includes chips to get analog HD I/O), and

    (C) it's indeed acceptable in my application to run slower than 30fps, which will undoubtedly happen as my pixel count goes up for various HD formats, if not already for SXGA.

    -Helmut