I want to buy a HiFi accessory that connects via Bluetooth and A2DP. Is there a loss of quality, because iOS reencode MP3, AAC to SBC? Some sources say so.
The manufacturer of the HiFi accessory claims that MP, AAC, Apple Lossless etc. are passed through directly. This should garantee excellent sound quality. But he can control only his end of the Bluetooth connection. How does Apple's Bluetooth stack behave?
iPhone 3GS, iOS 5.1.1
Check out this Apple doc -> iOS: Supported Bluetooth profiles
Advanced Audio Distribution Profile (A2DP)
Advanced Audio Distribution Profile allows high quality audio (stereo or mono) to be streamed from one device to another over a Bluetooth connection. This is commonly used to play music wirelessly from iOS to a wireless headset or a compatible car audio system.
I don't think that the streamed audio is downgraded, it should be the quality that's played on your iPhone.
Thanks! Apparently iOS supports only the mandatory SBC and MPEG-2 AAC.
AAC seems to be limited to 128 kbit/s.
I also checked the official Bluetooth specs 1.3 (page 22). http://developer.bluetooth.org/KnowledgeCenter/TechnologyOverview/Documents/A2DP _SPEC.pdf A maximum bitpool range seems to be equivalent to 320 kbit/s with Joint Stereo at 44.1 kHz
The device I'm interested in buying is Advance Acoustic's Apt-X Bluetooth Receiver WTX-500. http://www.advance-acoustic.com/en/produits/index/detail/id/92/sec/6
The product description reads: "Concerning MP3 or AAC files (at a lower rate than 350Kbits/sec), they are transmitted without decoding and thus without any degradation".
But, if iOS doesn't transmit MP3 at all and AAC only up to 128 kbit/s, what happens with high-quality MP3 or AAC files? Are the reencoded? At what quality level?
What codecs are supported with A2DP?
