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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
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