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Can't change encode frame rate

Mike Gilorma
Intellectual 305 points

I can't seem to change the encode frame rate using the encode demo program.  I'm aware that the decode program will play back faster because it is an elementary stream, but I can't even get that far.  I've tried setting the maxFrameRate, targetFrameRate, and refFrameRate, all to no avail.  I'm working on a dm365 board from Z3 and trying to encode mpeg4 video.  Any help would be greatly appreciated.

  • 0
    Intellectual 305 points

    Am I even correct in my understanding of how this will work?  My thoughts are that if I have a D1 video input (out of a DVD player ~ 30fps) and I set the target encoded video frame rate to 10000, that the encode program should only encode every 3rd frame that comes into it.    No matter how I try to lower the frame rate I am still encoding 30 fps.    I can just hack it up and manually choose which frames to encode, but then what is the point of the target encoded frame rate setting????

     

    Apparently other people have lowered their frame rates using the dynParams, I must be missing something simple.....

  • 0 in reply to Mike Gilorma
    Intellectual 305 points

    I can't believe that no TI expert has input on this one!!  It seems like something that many people would be interested in setting.  Lowering the frame rate allows you to reduce your bandwidth but still encode at a high bit rate, sounds good to me!

  • 0 in reply to Mike Gilorma
    TI__Mastermind 37340 points

    Mike,

    Please be patient with us; our codec expert is out of the office until next week and is likely the reason you have not received your answer yet.  I myself am on vacation but trying to help our customers where I can.  I will touch base with our codec expert next week and make sure he does not miss this.  Thank you for your patience.

  • 0 in reply to Juan Gonzales
    Intellectual 650 points

    Hey Mike,

                       That field does not actually control the eventual output from the encoder (i.e, it does not automatically give you dropped frames to meet your target framerate). That field is meant to tell the encoder the rate at which YOU are actually giving frames to it so that internally, it has awareness on how to do CBR/VBR bitrate statistics. In order to realize your intended goal of variable frame rate, you will have to manually drop frames going into the encoder and consequently, update this target frame rate fields as well to ensure proper CBR/VBR output rates.

    Jerry

  • 0 in reply to JerryJohns
    Intellectual 305 points

    Thanks so much for getting back to me on this!  Sorry if I seemed impatient, it totally could have waited till after your vacation as I already wrote the code to drop frames.  It would be helpful if in the codec user guides it mentioned the fact that setting the frame rate doesn't actually change the rate at which frames are encoded. 

     

    Thanks again!

  • 0 in reply to Mike Gilorma
    Intellectual 650 points

    Hey Mike,

                     I'm actually not on vacation (i'm not affiliated with TI), so no worries :) Hope it works out for you


    Jerry Johns
    Design Engineer
    Nuvation Research Corporation