• Rostislav Pehlivanov's avatar
    aacenc_tns: adjust coefficient calculation, add double filter support · e3faad81
    Rostislav Pehlivanov authored
    This commit improves the TNS implementation to the point where it's
    actually usable and very rarely results in nastyness (in all bitrates
    except extremely low bitrates it's increasing the quality and prevents
    some distortions from the coder being audiable).
    
    Also adds a double filter support which is only used if the energy
    difference between the top and bottom of the SFBs is above the
    thresholds defined in the header file. Looking at the bitstream
    that fdk_aac generates it sometimes used a double filter despite
    the specs stating that a single filter should be enough for almost
    all cases and purposes.
    
    Unlike FAAC or fdk_aac we sometimes use a reverse filter in case
    the energy difference isn't enought to use a double filter. This
    actually works better.
    Signed-off-by: 's avatarRostislav Pehlivanov <atomnuker@gmail.com>
    e3faad81
aacenc_tns.c 7.26 KB