Tempo changing and music quality

[rattley]

Hello!

In another post Fred Smith wrote:       "Tempo changes in audio files always lead to some sort of degradation. If you want to control the tempo, stick to midi files."

This got me thinking..........How does one know what tempo was actually used when a style was created?  I sometimes live record at a slower tempo and adjust it up to my liking later.  I understand "time stretching" and its limitations when changing tempos and keys. What really is going on inside my Genos when changing tempos or keys??  Are the audio files sampled in different keys or tempos?  However it is done I am quite pleased with how my Genos sounds when making these changes.  -charley

[mikf]

Styles are midi files so changing tempo is not a problem because midi files have no sound. They can played at any speed.  Audio files are a different kettle of fish. Changing the tempo of an audio file would also change its pitch - think of an old tape recorder played back at the wrong speed. Modern software allows audio files to be manipulated so they can be played at a different speed without this change in pitch, but what Fred is saying is that this manipulation can cause some quality degradation.
Mike

[Bachus]

Styles are midi files so changing tempo is not a problem because midi files have no sound. They can played at any speed.  Audio files are a different kettle of fish. Changing the tempo of an audio file would also change its pitch - think of an old tape recorder played back at the wrong speed. Modern software allows audio files to be manipulated so they can be played at a different speed without this change in pitch, but what Fred is saying is that this manipulation can cause some quality degradation.
Mike

Styles are midi based...
Except for the audio drums part

[Lee Batchelor]

Fred is correct about audio style quality being compromised with tempo changes, however, I find the Yamaha audio styles can tolerate a fairly wide scope of tempo changes that a lot of audio editing software can't provide. It must be the design of their processors that makes the difference.

For example, if the default tempo is 150 BPM, you can drop it to 120 BPM without a noticeable difference. Go down to 90 or so, and you may hear the the pitch start to waver and the audio quality degrade. Experiment.

[markstyles]

Changing pitch or tempo of audio files, require an algorhym.  Slight changes are not too noticeable. Generally the The audio is broken up into extremely small grains, and these are shortened or more of them are played to accommodate tempo changes, playback speed of the grains will deal with pitch changes.  Small changes are not to bad, but More drastic ones, generally result in sound changes, which some will find unacceptable..one might describe these changes a watery sounding.

Midi files are data only, so extreme pitch and tempo changes can be made with no issue. 

[Lee Batchelor]

Great description, Markstyles!