D'après ce lien il semble que tu ais raison Denis, sous certaines conditions
on pourrait avoir du bit perfect à travers le kmixerOn the software side, there are some more obstacles: in order to play multiple sounds simultaneously, a so called "kmixer" / "kernel audio mixer" (XP, 2000) respectively "audio service" (Vista) which is part of the sound subsystem of Windows mixes them together and adjusts the volume of the resulting stream. Contrary to popular belief, the kmixer of Windows 2000 and XP doesn't modify the sound and is thus bitperfect if these four conditions are met:
1. The PCM/wave volume slider of the mixer (sndvol32.exe) must be at its maximum. Some start-up applications modify the volume slider (e.g. hardware monitoring tools from Asus).
2. The player must be compiled for the same architecture that the OS was compiled for - e.g. 32 bit player on 32 bit OS, 64 bit player on 64 bit OS. This is the case for the vast majority of installations because the 64 bit version of Windows XP isn't very commonly used.
3. Applications other than the player mustn't play sounds, otherwise the two output streams will be potentially sample rate converted and mixed by the kmixer.
4. Applications which are using the soundcard for recording have to use the same sample rate as concurrently running applications which are playing sounds - the hardware uses only one clock generator and hence this limitation arises.
- Pas d'atténuation du volume par la commande d'xp.
- Que les drivers et le renderer audio player supportent le mode32 bits (si on utilise xp 64 que se passe il ? )
- Et enfin les 2 dernières conditions qui posent plus de questions : aucune autre appli ne doit accéder au kmixer car si les sample rate sont différentes le kmixer fait de la conversion sans rien demander.Qui n'a pas eu la surprise bien qu'ayant suprimer le sons systèmes d'avoir un message vocal de son antivirus annonçant fièrement que la base de virus était mise à jour, mais quelle est donc la freq d'échantillonnage de ce joli message...
Hum hum prudence est donc mère de sagesse surtout qu'en ce cas de figure ça ne coute strictement rien .
Idem je n'ai pas les connaissances suffisantes pour vérifier cette info
selon laquelle le k mixer n'aurait pas une pleine résolution de 16bits surtout sans plus de source:
What is the KMixer?
The KMixer is a part of Windows that enables your computer to take multiple audio sources and play them back at the same time and at the same bit rate. The KMixer is also how Windows handles your volume control. Regular CD audio is 44.1 kHz. Many times, due to poorly written drivers, sound cards that will interact with the KMixer wil cause this 44.1kHz data to be resampled to 48kHz. Obviously this will result in an undesireable result when trying to achieve the upmost in sound quality. The mixing algorithm as implemented by Microsoft has been shown in many cases to only have a signal to noise ratio of about 92dB. CDs have a signal to noise ratio of about 96dB (technically 97.5dB). The KMixer effectively reduces the data from 16bit to 14 bit.
Mais sans vouloir couper les cheveux en 4, je pense que le principe de précaution, ie utiliser le ks ou l'asio ous xp (vista ça semble autre chose) ne peut nuire.
Donc je préfère garder mes bits parfaits.