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H.264 Quantization Parameter limitation.

Vinod Gowda
Prodigy 195 points

Hello All,

This is question related to h.264 code

i was trying to reduce bitrate by increasing the Quantization parameter (QP) in h.264 encoder code which i was running on TI board.

the QP when increased beyond 47 in the code gives distorted output which seems understandable since QP is so high.

But my reconstructed video looks fine where as my decoded video looks much worse. why is that happening?

Also is there any limitation of QP for luma at 47. like 47 for luma and 51 to chroma?

i am new to video codec and will  be highly grateful if some one could help.

i am running with slice as 1.

Thanks in advance.

  • 0
    Intellectual 880 points

    Hi Vinod,

    Can you please provide more details on Platform, used configuration files etc?

    Regards

    Rama

  • 0 in reply to Ramamohana Reddy
    Prodigy 195 points

    Hi,

    the platform is C64x+ and config file is

    InputFile                     = test.yuv
    EncodedFile              = Testout.264                                    
    ImageWidth               = 1280 
    ImageHeight             = 720 
    FramesToEncode    = 1500                                             
    IntraPeriod                 = 30                                                     
    IDRPeriod                  = 30                                                     
    ProfileIDC                  = 77                                                    
    LevelIDC                    = 40                                  
    InitalQP_I                   = 25                                                  
    InitialQP_P                = 25                                                     
    InputChromaFormat     = 4:2:0  
    NoOfReferenceFrames   = 1                                                 
    RateControl               = 1                                                      
    BitRate                       = 2000000                             
    FrameRate                = 60                                 
    EntropyCodingMode     = CABAC                                                  
    InputFrameformat         =  Progressive                                                    
    NumOfSlices                 = 1

    Hope this will help.

    Thanks,

    Vinod

  • 0 in reply to Vinod Gowda
    TI__Expert 3715 points

    Vinod,

    Can you please let us know the download link - from where you have downloaded the codec?

    Thanks,

    Vivek