cyx a écrit:le jitter, personne n'en a jamais constaté je pense. d'ailleurs un professionnel du domaine l'affirmait il y a quelques temps.
The main reason Digital sounds bad.
Fact: Digital audio data is 'just' 0's and 1's. There may be many formats (.wav, .aif, CD-audio) but the information is still digital. There is no loss during format conversion, provided the formats don't utilize compression.
Fact: Copying CD's (if they aren't damaged physically) is a lossless procedure. You can extract CD-audio with your computer and generate a file on your hard disk. Compare this file with the file created when you extract the same audio using a $30,000 player, the resulting two files are identical. This is proven by countless mathematical experiments and by HEX comparison programs.
The question which naturally arises out of this paradox is: why does the $30,000 player sound better?
At the Digital Out of a $100 CD-player we have the same 1's and 0's as we do in the $30,000 player. The only difference is in the Jitter content. The presence of Jitter means that the data (the 1's and the 0's) is not perfectly time-aligned, but is transmitted either slightly earlier or later than it should be in the ideal case. However, this time flaw is not as great as to cause a digital error (data fallout). But to our analogue ears, this translates into the harsh distortion we call "that digital sound."
Jitter is not a digital error.
Now if you know that, then you must ask: so how does the expensive CD-transport justify its price? Ah, Jitter. The cheap ones shake and the expensive ones don't.
Well, that's partly true. …
http://www.lessloss.com/about.htmlJitter, Bits, & Sound Quality
Jitter is not what digital sound quality induces in the listener; rather it is the instability in the clock signal that controls exactly when the analog waveform is sampled in the original A/D conversion, or when the digital word input into a DAC results in an analog voltage being produced at the chip's output. "So what?" is the response of digital advocates, "As long as a digital one is recognized as a one and a digital zero as a zero, then how can there be any difference in sound?" goes their argument, normally culminating in a fervently expressed "Bits is bits!"
Would that things were that simple. As my violin teacher used to say, "The right note in the wrong place is the wrong note." It's the same with digital data …
http://www.stereophile.com/reference/1290jitter/le jitter, cet ennemi maîtrisé
Ces premiers choix techniques résultent dans une meilleure gestion du jitter, ennemi bien
connu de la lecture numérique induisant notamment des disruptions temporelles, particulièrement critiques voire insurmontables dans le choix des éléments séparés drive/conversion (horloges multiples, câble de liaison numérique, etc.), et ressenties à l’écoute par des qualificatifs tels qu’ « artificiels » ou « numérique ». Mais cela ne s’arrête pas là : Resolution Audio a développé pour l’Opus 21 nombre d’innovations synergiques, telles que le filtrage exclusif en amont de l’étage de conversion, son horloge unique ultra-optimisée, le circuit court tri-dimensionnel, beaucoup plus coûteux à réaliser que les schémas « plats » traditionnels, mais les seuls permettant la réduction significative de la distance à parcourir par le signal, ou encore l’absence de sortie numérique, chacune concourant à une réduction jamais atteinte des effets néfastes du jitter.
la signature analogique à l’ère du numérique
La technique est une chose, mais sans conteste, la véritable force de l’Opus 21 sont ses résultats en termes de restitution sonore. Expressivité, suivi mélodique, transparence, extension
et équilibre sur la totalité de la bande passante, assortis d’une finesse micro-dynamique hors norme, confère à l’Opus 21 un caractère unique à l’ère du numérique, empreint de velouté et de naturel.
http://www.inlegato.com/docs/plaquette_Resolution.pdfcyx a écrit:et d'ailleurs pour des formats lossless ce n'est pas "décodage" mais "transcodage" donc 0 pertes.
"Décodage" est le terme utilisé par "DTS"
You can enjoy DTS-HD Master Audio and DTS-HD High Resolution Audio if you have a new Blu-ray Disc or HD-DVD player with a DTS-HD Audio decoder built into the player. The audio will be decoded inside the player and passed to the receiver in two different ways.
http://www.dts.com/dts-hd/dtshd-master- ... ceiver.phpet par "Dolby".
Eventually, A/V receivers will have direct access to Dolby® Digital Plus or Dolby TrueHD bitstreams. We are working with the IEC and HDMI organizations to update data protocols to enable future versions of these high-bandwidth interfaces to carry these bitstreams.
To decode these bitstreams, the A/V decoder will need to support the updated data protocols, as well as incorporate these new decoding algorithms.
http://www.dolby.com/consumer/technolog ... vrs_3.html
