I have a number of MP4 files which are also available on YouTube, since long ago.
These videos are basically showing Music Sheets while a Piano is playing them.
The piano is not real, so this is quite similar to playing a MIDI file.
I understand MIDI files can have different sounds and behaviors depending on the devices playing them, but I expect Videos/Audio files should always play the same.
One strange behavior I noticed today is that these videos are suddenly playing the "higher notes" of Piano a bit "out of tune", like if notes are being played wrong or piano needs to be tuned.
Two examples below. What I mean can be heard from beginning of the first video, and almost at the end of the second video (1:50 to 2:00).
What I tried:
- PC with speakers (that's how I noticed the issue)
- PC with headphones
- Mobile phone
- YouTube (in case my MP4 files were corrupt)
- Converted to MP3
ALL of these have the same weird high-note problem.
I'm absolutely sure I was hearing the songs/notes properly before.
How can this be explained, given that the files (and YouTube video) weren't changed, and the same behavior is happening on both PC (Windows) and Mobile (Android) ?