Hello! I would like to let you know that Serge from soundexpert.org did in last month some research on aptX and its quality. Detailed article is on the following website, specially see parts added around "August 2018": http://soundexpert.org/news/-/blogs/audio-quality-of-bluetooth-aptx ============ Conclusions: aptX codec used in BT applications is no better than SBC at 328. Despite slightly lower algorithmic delay of aptX both SBC and aptX codecs provide the same 100-150ms latency in real-life BT applications. If you hear the difference between SBC and aptX in some BT product, there can be only two explanations - placebo effect or using SBC in Middle or Low Quality modes. AptX is just a copper-less overpriced audio cable. aptX HD is high-bitrate version of aptX. It has clearly noticeable increase in sound quality (not dramatic though taking into account the increase in bitrate) ============ And it just confirms my own testing. Whatever I did I was not able to either hear or see difference between aptX and SBC encoded-->decoded audio. I had discussion with Serge and there are some ideas which Linux Bluetooth A2DP software could supports: 1) Allow user to specify SBC codec quality. In most cases, including pulseaudio, SBC quality is chosen either to middle or low, not to maximum bitpool. In some cases SBC at high quality can provide better quality as aptX and more important -- SBC is supported by all headsets. 2) Show user current SBC codec quality. So user would know what was chosen and what should expect. I was told that Windows's Toshiba bluetooth stack has support for this indication. 3) In some cases SBC SNR bit allocation method can provide better quality as SBC loudness method. So then I could ask question: 1) What to do with aptX? It is really useful for users to have it in Linux & pulseaudio? Because it looks like that the only thing which it has better is lower latency. But can pulseaudio on Linux system really achieve it? 2) Should we rather look at increasing quality of SBC codec in pulseaudio? And if yes, how should be quality of SBC configured? Via profiles? Or to invent some new protocol options? Can we increase default SBC bitpool allocation? 3) If aptX is decided as useless, what about aptX HD codec? aptX HD codec is supported by less products (currently I do not own any), but this one may provide better quality as SBC according to that research. PS: That aptX research is the first and the only one about which I know. All other information about quality or other details which I found on internet are just marking informations. -- Pali Rohár pali.rohar at gmail.com
