• Attila Nagy's avatar
    Packing bitstream on-the-fly with delayed context updates · 52cf4dca
    Attila Nagy authored
    Produce the token partitions on-the-fly, while processing each MB.
    Context is updated at the beginning of each frame based on the
    previoud frame's counters. Optimally encoder outputs partitions in
    separate buffers. For frame based output, partitions are concatenated
    internally.
    
    Limitations:
        - enabled just in combination with realtime-only mode
        - number of encoding threads has to be equal or less than the
        number of token partitions. For this reason, by default the encoder
        will do 8 token partitions.
        - vpxenc supports partition output (-P) just in combination with
        IVF output format (--ivf)
    
    Performance:
        - Realtime encoder can be up to 13% faster (ARM) depending on the number
        of threads and bitrate settings. Constant gain over the 5-16 speed
        range.
        - Token buffer reduced from one frame to 8 MBs
    
    Quality:
        - quality is affected by the delayed context updates. This again
        dependents on input material, speed and bitrate settings. For VC
        style input the loss seen is up to 0.2dB. If error-resilient=2
        mode is used than the effect of this change is negligible.
    
    Example:
    ./configure --enable-realtime-only --enable-onthefly-bitpacking
    ./vpxenc --rt --end-usage=1 --fps=30000/1000 -w 640 -h 480
    --target-bitrate=1000 --token-parts=3 --static-thresh=2000
    --ivf -P -t 4 -o strm.ivf tanya_640x480.yuv
    
    Change-Id: I127295cb85b835fc287e1c0201a67e378d025d76
    52cf4dca
configure 17.1 KB