Why can't I hear a high-frequency sound when I play a YouTube video? For example, if you upload a 19khz high frequency to YouTube and play the iPhone , the high frequency will not come out. Why do you cut high-mainstreamers on YouTube?
YouTube uses 128 kbit/s AAC custom encoder for most videos, which they ran a blind study on and found it indistinguishable from 320 kbit/s MP3. However, this study involved mostly university students, and those were too old to hear these high frequencies, so that it cuts off high frequencies went undetected. However:
Opus, which is used for most playbacks on the web and will soon be used on Android, does not have this problem.