What are the differences in the quality of sound output when the
volume is changed in the following environments:
Usually, none, because the players just pass through the audio(after necessary decoding due to the codec, not the amplitude). On a separate note, there would have been a difference if the audio was fed directly into an internal/external DAC (sound card) because of better noise ratio.
Is there any difference between the 3
Yes. Media player amplifies only your songs and its inherent noise signals. But the OS will amplify all the inputs, of which media player is only one. We have the default Windows sound engine that gives the sound notifications, and potentially many more, like chrome that opens up a channel. So, Windows will amplify your song and all the noise that come from other inputs. The final effect is not that bad because most inputs are designed such that when there is no sound output, it closes the path, thereby avoiding noise. Also, for a user, it is more convenient to handle just one volume control.
Windows 10 volume slider in bottom-right corner
The OS changes the amplitude of all audio being routed through the sound card. OS knows the absolute high and low that your sound card supports - so can better judge the feasible levels and gradations.
Media program such as VLC player when playing a music file and Media
program such as Spotify when streaming music
It decodes, reduces amplitude, and sends to the OS.
Notes
- We set the media player volume at 150% and windows at 10%. Quality
is bad, volume would be low (because end result would be 15%). VLC
artificially amplifies the signals using interpolation, thereby
adding noise.
- We set the media player volume at 10% and windows at 90%. Quality
is fine, volume would be low (because end result would be 9%).
Neither the media player or the OS messes with the actual signal,
hence no losses.
- We set the media player volume at 90% and windows at 10%. Quality
is fine, volume would be low (because end result would be 9%).
Neither the media player or the OS messes with the actual signal,
hence no losses.
- Some media players like Windows Movies etc. uses the latest Windows
SDKs and hence hands over all the volume change inputs directly to
the OS through SDK. So when you move the voume slide inside the
Windows Movies, the OS slider also moves. This is an optimal
solution, since it reduces one step of pass through.
- When the volume at high levels like 70% above will sound worse
usually, but the culprit is the speaker system that cannot handle frequencies at that amplitude. Neither the OS, nor the media player is the issue.