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maximum/minimum frame-rate

ranchu
Guru 20755 points

Hello,

I would like to understand please if there are any limitation on maximum or minimum frame-rate on encoders/decoders of DM8168 HDVICP2.0.

1. in MPEG-4 encoder UG it is said that refframerate is 30fps by default, and supported values "ignored". the target rate if 30fps, and supported values are according to Level. What does it mean that refframerate default is 30fps, while supported values are ignored ? Does it mean that the limitation of maximum 30fps ? Can it reach 60fps ?

2. In MPEG-4 decoder UG it is said that deos not use maxframerate, but the maxframerate is set to 30fps. What does it mean ? Can it reach 60 fps ?

3. Is the minimum fps for any of these encoder/decoder can be 0 fps, or is it a higher value ?

Best Regards,

Ran

  • 0
    TI__Expert 5000 points

    The target and ref frame rate in the encoder context are used to calculate the bit budget for the rate control algorithm. And also the paramter might be encoded in the bitstrream as part of VBV info etc. This parameter does not make the encoder to spit out those many frames every sec. The frame rate of the encoder depends on the number of process() calls made of the encoder per sec. If the HDVICP2 is clocked higher, the MPEG4 encoder can achieve 1080p60fps even.

    Coming to decoder, the maxFramerate is basically dont care quantity. Again here the fps is decided by the number of process() calls getting completed every sec.

  • 0 in reply to Venugopala
    Guru 20755 points

    Hi Venugopala,

    Thank you for clarification about the stream bitrate,

    >The target and ref frame rate in the encoder context are used to calculate the bit budget for the rate control algorithm.And also the paramter might be encoded in the bitstrream as part of VBV info etc.

    Still the question remains in if there is any issue here in terms of wrong bit budget calculation for rate algo, or/and wrong VBV info ? Shouldn't the refframerate and targetbitrate be set with the correct rate or should it totally be ignored ? If it should be ignored, then why is it set to default value ?

    Regards,

    Ran

  • 0 in reply to ranchu
    TI__Expert 5000 points

    Some of the parameters are generic as the codec follows IVIDENC2 interface.

    Hence if some of the parameters are not really cared they are assigned with default value.

  • 0 in reply to Venugopala
    Guru 20755 points

    Hi Venugopala,

    If I may please ask one more thing on this issue... If we set targetframerate to 30fps, while the doing the encoding (.process call) in 29.97 fps, what does it mean ? will it result in frame loss ?

    Regards,

    Ran

  • 0 in reply to ranchu
    TI__Expert 5000 points

    There is no frame loss..The encoding performance is 29.97fps which is as well treated as 30fps.