• Zoe Liu's avatar
    Support ext-skip for both low delay and high delay · 104d62e1
    Zoe Liu authored
    For both low delay and high delay scenarios, the reference pair in
    skip mode are specified as the closest fwd ref, together with the
    closest bwd ref if there is any bwd ref, otherwise with the two
    closest fwd refs.
    Skip mode by default uses COMPOUND_AVERAGE. When all the reference
    frames are on the same side, temporal-distance weighted compound is
    considered, and a compound index is signaled to indicate whether
    distance-weighted compound or compound-average is usd.
    Whether to use distance-weighted compound for skip mode is still
    under experimenting, hence a flag is temporarily added:
    Following experimental results are obtained over 30 frames, using the
    setup of --disable-ext-partition --disable-ext-partition-types
    --disable-txmg --enable-jnt-comp --enable-mfmv --enable-ext-skip:
    (1) High Latency:
    For Google test sets (lowres/midres), the BDRate coding gain is ~0.2%;
    For AWCY, the coding gain is ~0.1%.
    (2) Low Latency:
    No gain has been observed over Google sets and ~0.1% gain is obtained
    only when temporal-distance weighted prediction is used.
    Change-Id: I8c433357adebed0126ebfdd5c4d51aa71e64be57