Re: xHE-AAC: Transparency Rate?
Reply #11 – 2021-05-31 09:23:13
On my side, my tagged classical music library was very recently encoded to xHE-AAC with Exhale at ~96 kbps. Before that and following this test I made , my library was built upon LC-AAC 144 kbps, LC-AAC 128 kbps and also Opus 100 kbps for experimental purposes. As a result I never heard anything annoying with LC-AAC 144 kbps; LC-AAC 128 was close to transparency on a huge majority of tracks and all irritating issues I had were always with Opus 100 kbps encodings (in other words each time I heard something wrong and checked the file format it was an Opus encoding — and it happened countless times). At the moment Exhale -3 (average bitrate: 98 kbps on ~1000 hours of music) gives a pretty high quality on many tracks but I still hear from time to time some audible distortions I didn't heard with LC-AAC 128 kbps. I would say, for my hearing and for my music (and from my very little experience too) that USAC brings a real but small gain compared to a fully mature AAC encoder at this bitrate level. I'm sure Exhale outperforms AAC at 96 kbps; I'm quite sure it's not as good as AAC ~128 kbps. So Exhale 96 kbps is somewhere between 96…128 kbps AAC range. And again, most encodings are absolutely fine and can even compete with any high bitrate encodings (depending on how critical your listening abilities and settings are). NB : I'll soon publish a test that compares Exhale vs FhG USAC vs OPUS at 96 kbps