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  • Fiona Glaser's avatar
    Early termination for chroma encoding · 205a032c
    Fiona Glaser authored
    Faster chroma encoding by terminating early if heuristics indicate that the block will be DC-only.
    This works because the vast majority of inter chroma blocks have no coefficients at all, and those that do are almost always DC-only.
    Add two new helper DSP functions for this: dct_dc_8x8 and var2_8x8.  mmx/sse2/ssse3 versions of each.
    Early termination is disabled at very low QPs due to it not being useful there.
    Performance increase is ~1-2% without trellis, up to 5-6% with trellis=2.
    Increase is greater with lower bitrates.
    205a032c