A discussion elsewhere whether YouTube really do preserve uploaded videos audio content up to 20 kHz, or limits it to 16 kHz spurred my curiosity to look into it, and for the investigation I looked up a few audio frequency sweep test videos and chose the following video for this brief investigation.
All audio files were downloaded directly from YouTube as an incognito user, no external download helper website were used as these services usually convert the audio into MP3 format which degrades the audio quality even further, but also the conversion parameter settings aren't known either.
As for YouTube they still offer AAC audio codec usually with the legacy MP4 video container format, but around 2011 YouTube started switching over to WebM (Web Media, usually used by online video platforms) container wherein the video comes in VP8, VP9 or AV1 codec format, and audio in OPUS codec format.
After having downloaded the various audio files I were able to grab, the files were then analyzed with Audacity, the spectrogram setting was limited between 15 kHz and 20 kHz as that is the frequency range of interest, and the following results were found:
( Each downloaded audio files file-data were analyzed on-line with: https://mediaarea.net/MediaInfoOnline
And the title above each image (codec, sampling rate, bit rate) stems from the data analysis for each file. )
AAC 44.1kHz 127kbs
Opus 48kHz 74kbs
Opus 48kHz 103kbs
Opus 48kHz 171kbs
Conclusion: As YouTube nowadays stream virtually only by using WebM (OPUS) one can consider they do support 20 kHz audio bandwidth.
Disclaimer: As this was a rather brief investigation, the results are presented as is with its limitations, there are much more info on Google Support what audio and video formats and qualities YouTube supports.
All audio files were downloaded directly from YouTube as an incognito user, no external download helper website were used as these services usually convert the audio into MP3 format which degrades the audio quality even further, but also the conversion parameter settings aren't known either.
As for YouTube they still offer AAC audio codec usually with the legacy MP4 video container format, but around 2011 YouTube started switching over to WebM (Web Media, usually used by online video platforms) container wherein the video comes in VP8, VP9 or AV1 codec format, and audio in OPUS codec format.
After having downloaded the various audio files I were able to grab, the files were then analyzed with Audacity, the spectrogram setting was limited between 15 kHz and 20 kHz as that is the frequency range of interest, and the following results were found:
( Each downloaded audio files file-data were analyzed on-line with: https://mediaarea.net/MediaInfoOnline
And the title above each image (codec, sampling rate, bit rate) stems from the data analysis for each file. )
AAC 44.1kHz 127kbs
Opus 48kHz 74kbs
Opus 48kHz 103kbs
Opus 48kHz 171kbs
Conclusion: As YouTube nowadays stream virtually only by using WebM (OPUS) one can consider they do support 20 kHz audio bandwidth.
Disclaimer: As this was a rather brief investigation, the results are presented as is with its limitations, there are much more info on Google Support what audio and video formats and qualities YouTube supports.
