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Frame Order in decoding

ranchu
Guru 20755 points

Hello,

I would please like to understand How the framework deals with decoding bitstream in terms of frame order:

1. If AVSYNC is disabled, the frames will not be presented in PTS order. isn't it a problem in terms of percieved video ?

2. Does the bitstream is required to be delivered to decoder in the DTS order, or the decoder can recieve the same order as in the bitstream from MPEG-TS for example.

Best Regards,

Ran

  • 0
    TI__Expert 6950 points

    Decoder provides output in display order. So just feeding a bitstream as is should be enough. Even without AVSync in place, display controls the timing of frames and they get displayed in proper presentation order.

  • 0 in reply to Sivagamy Govindasamy
    Guru 20755 points

    Hi Sivagamy,

    Thanks for the quick response!
    Are you saying that the decoder can recieve the bitstream arranged as is from transport stream(DTS order), and will change the frame order to be in PTS order ?
    and there is no need to use AVSYNC enabled or SWMS in chain, so that the chain can be as simple as decoder->display ?

    >Even without AVSync in place, display controls the timing of frames and they get displayed in proper presentation order.
    Do you mean here that even if frames are recieved into display (not decoder!) in any order whatsoever they will be displayed in the right order (PTS) ?

    Thanks,

    Ran

  • 0 in reply to ranchu
    TI__Guru 59700 points

    Regarding:

    Do you mean here that even if frames are recieved into display (not decoder!) in any order whatsoever they will be displayed in the right order (PTS) ?

     

    - No . Display link will display frame in FIFO order. Decoder internally converts from decode order to display order. Display link does not consider PTS for rendering. Frames will be displayed at display frame rate disregarding PTS.If no new frame is available at input of display link, previous frame will be repeated.

  • 0 in reply to Badri Narayanan
    Guru 20755 points

    Hi Badri,

    Thanks,  can you please check the following issue:

    1.

    >Decoder internally converts from decode order to display order

    Is it the decoder link that changes the order of frames after the decoder codec finished its process ?

    2. Does the decoder API (vdec_putBitstream) requires that given frame order should be in DTS order and is it the same order as in transport stream, i.e. the bitstream are delivered as is from stream into decode MCFW API  ?

    3. Is SWMS Link required in chain for displaying in display order ?


    Thank you for your time!

    Ran

  • 0 in reply to ranchu
    TI__Guru 59700 points

    Is it the decoder link that changes the order of frames after the decoder codec finished its process ?

      - Yes

    Does the decoder API (vdec_putBitstream) requires that given frame order should be in DTS order and is it the same order as in transport stream, i.e. the bitstream are delivered as is from stream into decode MCFW API  ?

    - Yes.Input should be in same order as transport stream .i.e decode order.

    Is SWMS Link required in chain for displaying in display order ?

    - No SwMs is not required for displaying in display order.