{"id":5503,"date":"2017-02-11T12:09:43","date_gmt":"2017-02-11T12:09:43","guid":{"rendered":"https:\/\/wfsdiy.wordpress.com\/?page_id=2"},"modified":"2017-02-11T12:09:43","modified_gmt":"2017-02-11T12:09:43","slug":"about","status":"publish","type":"page","link":"https:\/\/wfs.pixetbel.org\/index.php\/about\/","title":{"rendered":"Pourquoi la WFS, why?"},"content":{"rendered":"

Ressources et exp\u00e9rimentations en lien avec la synth\u00e8se de front d’onde appel\u00e9e en Anglais Wave Field Synthesis <\/em><\/strong>(WFS<\/strong>). Avec cette approche la localisation s’appuie essentiellement sur le calage des retards pour chaque source et chaque haut-parleur. Cela demande une matrice de retards, chose qui est aujourd’hui possible avec les ordinateurs tr\u00e8s rapides \u00e0 notre disposition ou la flexibilit\u00e9 des consoles num\u00e9riques.<\/p>\n

Ces recherches sont faites dans l’optique d’appliquer cette technique \u00e0 la sc\u00e8ne pour des sources lives<\/em>, pr\u00e9sentes sur sc\u00e8ne, et des sons enregistr\u00e9s ou synth\u00e9tiques.<\/p>\n

La mise \u00e0 disposition de ces informations est l\u00e0 pour permettre de d\u00e9mocratiser cette approche qui offre de nombreux avantages par rapport \u00e0 une lat\u00e9ralisation par les niveaux uniquement.
\nL’approche classique h\u00e9rit\u00e9e de l’\u00e9poque des tables de mixage analogiques place uniquement les sources entre les enceintes gr\u00e2ce \u00e0 leur diff\u00e9rence d’intensit\u00e9. Une impression de distance peut \u00eatre ajout\u00e9e par un dosage de la r\u00e9verb\u00e9ration. Cette technique a une limite, elle fonctionne surtout dans l’axe m\u00e9dian entre les enceintes. D\u00e8s qu’on se situe un peu hors de l’axe on n’a l’impression que le son vient essentiellement d’un c\u00f4t\u00e9 ou d’un autre. On peut \u00e9ventuellement travailler avec trois enceintes pour combler le centre et \u00e9viter de telles bascules dans la perception de la lat\u00e9ralisation des sources.
\nD’autre part la lat\u00e9ralisation d’une source fait baisser le niveau du c\u00f4t\u00e9 oppos\u00e9. On obtient sur les c\u00f4t\u00e9s de la zone d’\u00e9coute des mix o\u00f9 l’\u00e9quilibre global n’est plus celui entendu sur l’axe m\u00e9dian.<\/p>\n

La synth\u00e8se de front d’onde aborde les choses autrement : On recr\u00e9e la courbure des fronts d’onde par des retards variables pour restituer la propagation du son comme les ronds dans l’eau qui s’\u00e9cartent de l’endroit o\u00f9 on aurait jeter un cailloux dans un \u00e9tang. On ne touche qu’assez peu aux niveaux. Cela permet d’avoir un mix plus homog\u00e8ne dans tout le public et de donner une impression de localisation lat\u00e9rale mais \u00e9galement en profondeur dans toute la zone d’\u00e9coute.<\/p>\n

Remerciements personnels :<\/em>
\nTh\u00e9\u00e2tre Garonne, Compagnie Lato Sensu Museum et Christophe Bergon, Third World Bunfight pour les essais et les occasions de mettre tout \u00e7a en pratique.<\/em><\/p>\n

\n

Why WFS?<\/span><\/h1>\n

Here are some resources and experimentations with Wave Field Synthesis<\/em><\/strong> (WFS<\/strong>). This method for placing sound in a soundfield relies extensively on a delay matrix calculated from the distances between each source and each speaker. Nowadays this is possible to program on a fast computer and with the flexibility of modern digital consoles.<\/span><\/p>\n

The research here is done with sound reinforcement as a target for live sources or playback and synthetic soundtracks.<\/span><\/p>\n

The information on this blog is made available in the spirit that this technique will find a broader user-base since it solves a lot of the pitfalls that level based panning runs into.<\/span>
\nThe regular method for placing a sound in a soundfield is inherited from the days of analogue consoles. A sound that will be louder in one of the speakers will seem to come from that direction. To have a sense of distance you add more or less reverb on top. This technique works well when standing at equal distance from the speakers, but as soon as one is off this axis, one will have the impression sound comes from one side or the other. Adding a third speaker in the center will stabilize things slightly.<\/span>
\nAn other pitfall is that when you pan a sound to one side it becomes fainter on the opposite side and thus the mix will sound different when far off to the side of the axis running at equal distance from the speakers.<\/span><\/p>\n

Wave field synthsis deals with placing sources in the soundfield very differently. It tries to recreate the wave front of each source with variable delays and very little level processing. Think of how waves will propagate at the sruface of water from a stone thrown into a pond. This gives a much more homogenous mix in the whole audience and not only an impression of left-right but also of depth in the stage area.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

This is just a short excerpt for the about page.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":1,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-5503","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/pages\/5503","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/comments?post=5503"}],"version-history":[{"count":0,"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/pages\/5503\/revisions"}],"wp:attachment":[{"href":"https:\/\/wfs.pixetbel.org\/index.php\/wp-json\/wp\/v2\/media?parent=5503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}