carmiyu
22nd September 2005, 12:06
Hi,
I am reading H.264 spec and can't find the constraint of max reference frame number. Although spec says num_ref_frame must be within 0 to MaxDpbSize, inclusive, the MaxDpbSize is defined using units of 1024 bytes. Take Level 3.0 as example, if the input frame size is 720 * 576, MaxDpbSize is Min(1024xMaxDPB/(PicWidthInMbs*FrameHeightInMbs*384),16)=5 and therefore max. ref frame number is also 5. If the input frame size is smaller, saying 176* 144, MaxDpbSize is Min(1024xMaxDPB/(PicWidthInMbs*FrameHeightInMbs*384),16) = 16 and therefore max. ref frame numer is 16. So the max. reference frame number is actually determined by input frame size and max buffer size given by level. Am i saying this right??
Best regards,
carmiyu
I am reading H.264 spec and can't find the constraint of max reference frame number. Although spec says num_ref_frame must be within 0 to MaxDpbSize, inclusive, the MaxDpbSize is defined using units of 1024 bytes. Take Level 3.0 as example, if the input frame size is 720 * 576, MaxDpbSize is Min(1024xMaxDPB/(PicWidthInMbs*FrameHeightInMbs*384),16)=5 and therefore max. ref frame number is also 5. If the input frame size is smaller, saying 176* 144, MaxDpbSize is Min(1024xMaxDPB/(PicWidthInMbs*FrameHeightInMbs*384),16) = 16 and therefore max. ref frame numer is 16. So the max. reference frame number is actually determined by input frame size and max buffer size given by level. Am i saying this right??
Best regards,
carmiyu