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Aspect Ratio

ranchu
Guru 20755 points

Hello,

 

I would please like to verify the following:

  1. In H.264 codec there is SAR parameter with set of values, and also extended aspect ratio value. Can The encoder can put with the extended any SAR value it intends ?
  2. Is the meaning of SAR in coded is actually DAR (display aspect ratio) i.e. not horizon_pixels/vertical_pixel but the aspect ratio intended in display (shouldn’t it be abbreviated as DAR) ?
  3. Can we be sure that any decoder does nothing with this value, but only delivers it to application ?
  4. Should the application use the aspect ratio in elementary stream or that of transport stream ? How is it usually done ? Is the TS aspect ratio must be the same as ES ?
  5. In general from application point of view, should application use the parameters in TS (codec type, aspect ratio, DAR,SAR, fps) or the overlapping parameters from ES ?

 

Best Regards,

Ran

  • 0
    TI__Genius 17215 points

    Ran,

    • In H.264 codec there is SAR parameter with set of values, and also extended aspect ratio value. Can The encoder can put with the extended any SAR value it intends ?
    >>Yes, Please see the description in the user guide for "aspectRatioIdc". it allows you to put the both the predefined value and extended SAR.
    • Is the meaning of SAR in coded is actually DAR (display aspect ratio) i.e. not horizon_pixels/vertical_pixel but the aspect ratio intended in display (shouldn’t it be abbreviated as DAR) ?
    >> The name is just taken from the H.264 spec.
    • Can we be sure that any decoder does nothing with this value, but only delivers it to application ?
    >> Yes
    • Should the application use the aspect ratio in elementary stream or that of transport stream ? How is it usually done ? Is the TS aspect ratio must be the same as ES ?
    >> We cannot answer this accurately as it totally depends how the TS and ES of the final system is like. In my opinion, TS values should be given more importance as these are more of system parameters.
    • In general from application point of view, should application use the parameters in TS (codec type, aspect ratio, DAR,SAR, fps) or the overlapping parameters from ES ?
    >> I suggest to use from TS. But again,  Customers like you should know it better based on the content you are handling.
    regards
    Yashwant
  • 0 in reply to Yashwant Dutt
    Guru 20755 points

    Thank you very much for the clarifications,

    Ran