• Zoe Liu's avatar
    Speed up ref selection by enforcing max 6 frames · f452fdfe
    Zoe Liu authored
    A speedup feature that enforces the maximum number of reference frames
    to evaluate for each arbitrary frame to be 6, as opposed to the maximum
    syntax-allowed number of reference frames which is 7, through the
    following rules:
    
    (1) When all the possible reference frames are availble, we reduce the
        number of reference frames (7) by 1 by removing one reference
        frame;
    (2) Always retain GOLDEN_FARME/ALTEF_FRAME;
    (3) Check the earliest 2 remaining reference frames, and there are two
        options to remove one reference frame:
        (a) Remove the one with the lower quality factor; Otherwise if
        both frames have been coded at the same quality level, remove the
        earliest reference frame;
        (b) Always remove the earliest reference frame.
        Currently set option (a).
    
    This patch has demonstrated an encoder speedup of ~8.5%. It is under
    speed2 with "selective_ref_frame >= 2". (May be considered to move
    to speed1 later once the coding performance impact is evaluated
    further.)
    
    Using the following configure setups, the coding performance has been
    dropped on Google test sets (50 frames) in BDRate by ~0.2% for lowres
    and by ~0.1% for midres:
    --enable-experimental --disable-convolve-round --disable-ext-partition
    --disable-ext-partition-types --disable-txk-sel --disable-txm
    
    Change-Id: I84317bae00bfd90b2c3d301858a849f441974e6f
    f452fdfe
ratectrl.h 8.78 KB