SayIT
22 May 2012, 08:46 *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
News:
 
  Home   Forum   Help Login Register   *
  Ştiri
   Hardware
   Software
   Internet
   Jocuri
   Diverse
  
  Teste şi prezentări
   Procesoare
   Plăci de bază
   Memorii
   Plăci video
   Diverse
   Software & Jocuri
Mesaje recente
[19 May 2012, 23:56]

[19 May 2012, 17:53]

[19 May 2012, 16:39]

[17 May 2012, 17:00]

by LNT
[17 May 2012, 10:18]

[16 May 2012, 18:52]

[08 May 2012, 09:14]

[08 May 2012, 09:12]
Members
Total Members: 360
Latest: Emeraldu
Stats
Total Posts: 17510
Total Topics: 1216
Online Today: 14
Online Ever: 233
(26 June 2007, 07:28)
Users Online
Users: 0
Guests: 13
Total: 13
Pages: [1]   Go Down
  Print  
This topic has not yet been rated!
You have not rated this topic. Select a rating:
Author Topic: Casti Bluetooth  (Read 555 times)
0 Members and 1 Guest are viewing this topic.
Chipicao Offline
Administrator


Cookies: 67
Posts: 1.595
« on: 21 May 2008, 09:24 »

As vrea sa cumpar o pereche de casti BT (stereo, A2DP) insa am o nelamurire. In ce fel va fi transmis sunetul de la PC la casti? Digital, analog? Placa de sunet mai are vreo legatura in toata treaba asta, sau se ocupa transmitatorul de tot?
Logged

μή μου τούς κύκλους τάραττε
IceCub Offline
Technology addict


Cookies: 41
Posts: 723
« Reply #1 on: 21 May 2008, 11:37 »

Din cate stiu, datele se trimit digital catre castile bluetooth, iar placa de sunet poate sa lipseasca din sistem.
Ignore user   Logged
tcalexander Offline
Brain eating


Cookies: 42
Posts: 261
« Reply #2 on: 21 May 2008, 11:53 »

Dacă e Bluetooth, ce să mai fie analog acolo? De placa de sunet nu ştiu ce să zic, tind să cred la fel.
Singura experienţă "up close and personal" cu căştile wireless a fost cu un set Conceptronics C08-022 care sux big time.
Ignore user   Logged

Would you like to ride on your own ass?
IceCub Offline
Technology addict


Cookies: 41
Posts: 723
« Reply #3 on: 21 May 2008, 12:04 »

Tin  minte ca am folosit un headset bluetooth (handsfree daca vreti) in combinatie cu un dongle bluetooth pentru conversatii pe YM / SkyPe, iar la preferinte a trebuit sa aleg sa trimita/primeasca sunetul de/la headset (era vazut practic ca o alta placa de sunet).

Quote
Advanced Audio Distribution Profile (A2DP)

This profile defines how high quality audio (stereo or mono) can be streamed from one device to another over a Bluetooth connection.[1] For example, music streamed from a mobile phone to a wireless headset.

A2DP was initially used in conjunction with an intermediate Bluetooth transceiver that connects to a standard output audio jack, encodes the incoming audio to a Bluetooth-friendly format, and sends the signal wirelessly to Bluetooth headphones that decode and play the audio. However, many Bluetooth 1.1, 1.2 mobile phones and portable media players do not natively support A2DP, while some newer Bluetooth 2.0 headphones do support it.

Bluetooth headphones, especially the more advanced models, often come with a microphone and support for the Headset (HSP), Hands-Free (HFP) and Audio/Video Remote Control (AVRCP) profiles.

A2DP is designed to transfer a uni-directional 2-channel stereo audio stream, like music from an MP3 player, to a headset or car radio.[2] This profile relies on AVDTP and GAVDP. It includes mandatory support for the low complexity SBC codec and supports optionally: MPEG-1, MPEG-2, MPEG-4, AAC, and ATRAC, and is extensible to support manufacturer-defined codecs. Most bluetooth stacks implement the SCMS-T digital rights management (DRM) scheme. In these cases it is not possible to connect the A2DP headphones for high quality audio.
« Last Edit: 21 May 2008, 12:19 by IceCub » Ignore user   Logged
Chipicao Offline
Administrator


Cookies: 67
Posts: 1.595
« Reply #4 on: 21 May 2008, 14:06 »

Asta stiam, dar semnalul e analog sau digital?
Logged

μή μου τούς κύκλους τάραττε
IceCub Offline
Technology addict


Cookies: 41
Posts: 723
« Reply #5 on: 21 May 2008, 14:24 »

Asta stiam, dar semnalul e analog sau digital?

Pai banuiesc ca prin bluetooth nu poti trimite semnalul decat digital...
Ignore user   Logged
Chipicao Offline
Administrator


Cookies: 67
Posts: 1.595
« Reply #6 on: 21 May 2008, 15:57 »

Aceeasi banuiala o am, dar din pacate nu am gasit nimic concret...
Logged

μή μου τούς κύκλους τάραττε
SoNic Offline
SuperDuper


Cookies: 41
Posts: 528
« Reply #7 on: 22 May 2008, 00:50 »

Semnalul este trimis digital, dar un "alt" digital decat cel de pe interfata spdif normala, un fel de mp3 fata de wav daca vrei. Oricum, castile in sine sunt atacate tot cu semnal analogic ca de, avem urechi analogice :P
Si da, castile bluetooth vor fi vazute ca o noua placa de sunet.
Logged

Unsigned integer
Chipicao Offline
Administrator


Cookies: 67
Posts: 1.595
« Reply #8 on: 22 May 2008, 02:50 »

Deci materialul audio este transformat intr-un semnal digital (diferit de SPDIF) care ajunge la casti si e transformat din nou in analogic. Stiam ultima parte, dar sunt curios pentru ca prea multe conversii nu cred ca fac bine...

Ultima intrebare, cine se ocupa de acea conversie, procesorul sau adaptorul BT? Si in ce masura poate fi afectata calitatea?

Ca idee, la SPDIF sa face vreo conversie sau sunetul e transmis "asa cum e", mp3, wav, flac, fara nicio conversie?
Logged

μή μου τούς κύκλους τάραττε
IceCub Offline
Technology addict


Cookies: 41
Posts: 723
« Reply #9 on: 22 May 2008, 11:27 »

Ca idee, la SPDIF sa face vreo conversie sau sunetul e transmis "asa cum e", mp3, wav, flac, fara nicio conversie?

In mod normal sunetul e convertit/comprimat intr-un format definit de standardul IEC 61937. Cel putin asa spune aici... Nu poti trimite suntul in format flac spre exemplu unui echipament care nu stie de acest format.
Ignore user   Logged
SoNic Offline
SuperDuper


Cookies: 41
Posts: 528
« Reply #10 on: 22 May 2008, 12:50 »

SPDIF este un standard/suport de transmitere a unor date digitale. Semnale standardizate care se trimit pe el sunt PCM (stereo, necomprimat), Dolby Digital (multicanal, comprimat) si DTS (multicanal, comprimat cu un bitrate mai mare decat DolbyDigital). Fisierele amintite de tine sunt formate de stocare pe HDD a datelor. De exemplu un fisier flac este "citit" de un player software, convertit in PCM si trimis la placa de sunet in acest format. La fel pentru mp3 - este convertit de player in PCM si apoi trimis la placa de sunet. Fisierele wav sunt cel mai aproape ca forma de formatul PCM, dar tot trebuie citite de pe hdd si atasat headerul PCM inainte de trimiterea spre placa de sunet.

Procesul la bluetooth este urmatorul:
1. Softul tau de redare citeste fisierele de pe HDD. Ele sunt transformate in PCM cu ajutorul CPU system si trimise la driverul placii de sunet.
2. In cazul cand placa de sunet sunt castile bluetooth, driverul acestora face conversia din PCM in standardul necesar transmisiei bluetooth. Evident pentru asta se foloseste CPU sistem.
3. Odata receptionate de castile alea, se face decodarea si conversia in PCM. Care PCM este trimis la DAC-urile interne si de acolo se obtine analogicul care ataca castile in sine.
Logged

Unsigned integer
Chipicao Offline
Administrator


Cookies: 67
Posts: 1.595
« Reply #11 on: 22 May 2008, 21:03 »

Am inteles perfect acum, mersi mult pentru explicatii. :sal:
Logged

μή μου τούς κύκλους τάραττε
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.16 | SMF © 2011, Simple Machines
TinyPortal v0.9.8 © Bloc
Valid XHTML 1.0! Valid CSS!