Baroque Ornamentation / Embellishments

[invictious]

Straight to the point, succinctly, at the risk of over-generalisation:

Baroque pieces apparently were performed in an improvisatory manner, with a great latitude as to the ornamentation or embellishment or even going beyond the score.

Any one can share more info about this? This actually accords with my rudimentary understanding of Baroque practice. Very roughly, in the exposition of the theme, one should play as written, but when the theme reappears, embellishment seems to be encouraged.

Is there any general rule or convention as to embellishing notes? It appears to derive from the necessity of emphasising certain notes, which was impossible because the harpsichord played at a flat dynamic level regardless of the force applied on the keyboard. Is there a line to be drawn between an exceedingly dry, note-for-note reading of the score, and a tastelessly over-embellished performance with mordents littered on every other note?

For example, may I suggest the following recordings:
A captivating recording of Bach's Toccata in E minor, BWV 914 by Blandine Rannou. Note the quantity of embellishments particularly in the Fuga.

A ridiculously refreshing and addicting interpretation of Vivaldi's Winter by Fabio Biondi. Also, note the insanely delicious cembalo in the beginning.

[nastassja]

Actually, there are rules.
 
Couperin's "L'Art de toucher le clavecin" has some pretty useful indications (you can even find part of it on Google books, hopefully this excerpt will work https://books.google.ca/books?id=CecBsvk7Oz0C&pg=PA16&lpg=PA16&dq=couperin+ornamentation+rules&source=bl&ots=VR7xtRVo3i&sig=RvgGiF5ElsiFyMJ7ziyXl_8nJTc&hl=en&sa=X&ved=0ahUKEwjV1LmUu6zRAhWM5oMKHeTRAFwQ6AEIKTAC#v=onepage&q=couperin%20ornamentation%20rules&f=false
). Otherwise, we have Bach's index which is commonly used, it's on most decent Urtext editions, you can also find it online but I guess you know it already.  

I think that one has to take into account the nationality of the composer (Baroque French composers use a different style) as well the place where the ornament is located, among other things.

Last time I played the French Ouverture to my teacher there were a couple of final ornaments that I wanted to play my way, but my teacher told me it was technically wrong because it did not respect the ornamentation rules   (and then I learned them the proper way and applied them to my non-French baroque pieces, and I got it wrong again lol).

From what I remember, when the theme reappears, you have more freedom (even for similar types of ornament, you should play them differently, to avoid a mechanical impression), but one has to be careful with the codas - for some reason*, it seems that only certain types of embellishments are allowed. And for free trills, acceleration is allowed, as long as you then make sure that the ending is synchronized with the notes played by your left hand. This way, it sounds free but not rhythmically clumsy.

*If anyone knows the actual rule, please do share 

[indianajo]

The Blandine Rannou recording was lovely, thank you for finding it.  I know almost nothing about baroque ornamentation, except as you say, when they put mordents on every other note I don't like it.  I learned the ornaments Busoni put in his editions as if they were inserted by JSB himself, which I know is wrong. I understand a college education in music is great for learning this topic.   
However great the Vivaldi performance might have been, the microphones used sound as if they were made in 1950,  cost $3. and contained crystals.  Great mikes for a ham radio, not for music.