aptX is Qualcomm's low-latency Bluetooth audio codec family. aptX Adaptive (2018) delivers up to 420 kbps with dynamic adjustment based on RF interference; aptX Lossless (2021) offers true CD-quality.
aptX standard: 352 kbps, 16-bit/44.1 kHz, ~40 ms latency. aptX HD: 576 kbps, 24-bit/48 kHz, ~250 ms latency. aptX Low Latency: 280 kbps, ~32 ms latency (gaming). aptX Adaptive: 420 kbps variable, smart RF management. aptX Lossless: 1.2 Mbps lossless (Snapdragon Sound only).
aptX requires Qualcomm chipsets on both sides. Apple devices don't support it (iPhones use AAC). Android Snapdragon-powered phones widely support aptX HD/Adaptive.