aptX
Qualcomm's lossy-but-quality Bluetooth codec family.
aptX is Qualcomm's Bluetooth audio codec, positioned between SBC and LDAC. Variants: aptX (352 kbps), aptX HD (576 kbps), aptX Adaptive (276–420 kbps with low latency), and aptX Lossless (~1100 kbps, requires Snapdragon Sound–certified phone + headphones). All require Qualcomm chips on both sides; Apple devices don't support aptX.