Android-fi!

[Psymon]

Øhhh... Det er vel ikke muligt at sende musikken ud analogt via bluetooth?

ps. ja android kan godt sende musik via bluetooth

[Claus-DK]

Jeg mener til en DAC med Bluetooth altså..

[Psymon]

Jeg tror Android kan sende via BT som så mange andre ting, men ved BT så sker der jo en eller anden form for resampling inen det sendes og igen ved modtagelse.

[Claus-DK]

Jeg har læst om en DAC der kan bruges via bluetoth, det er derfor jeg spørger, jeg kunne umiddelbart ikke finde noget på mon telefon der hed digitalt ud via bluetoth og jeg ved godt at alt hvad bluethooth laver er digitalt.
Mere et spørgsmål om den kan modtage et digitalt lydsignal og sende det til en DAC, eller om det er sendes er det samme som i hovedtelefonudgangen..

[MadsM]

Umiddelbart tror jeg sagtens den skulle kunne det, men hvordan den håndter processen og om der ændres på det oprindelige signal, det tror jeg kræver at man har større indsigt i hvilke protokoller der benyttes ved transmissionen.

[kvik]

Ikke hele svaret, men måske lidt nyttig baggrundsviden..


Bluetooth streaming

Bluetooth enabled music players offer the ability to wirelessly stream music to other Bluetooth enabled devices equipped with the Advanced Audio Distribution Profile (A2DP), including headphones, speakers, car stereo systems, PCs, phones and other MP3 players. Some manufacturers are also integrating the technology into bicycle, motorcycle, snowboard and other activity helmets that have built-in stereo headphones.


A2DP - Advanced Audio Distribution Profile (A2DP)

This profile defines how multimedia audio can be streamed from one device to another over a Bluetooth connection. For example, music can be streamed from a mobile phone, to a wireless headset, hearing aid & cochlear implant streamer, car audio, or from a laptop/desktop to a wireless headset.

The Audio/Video Remote Control (AVRCP) profile is often used in conjunction with A2DP for remote control on devices such as headphones, car audio systems, or stand-alone speaker units. These systems may also include microphones and use Headset (HSP) or Hands-Free (HFP) profiles for voice calling.

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.[1] This profile relies on AVDTP and GAVDP. It includes mandatory support for the low-complexity SBC codec (not to be confused with Bluetooth's voice-signal codecs such as CVSDM), and supports optionally: MPEG-1, MPEG-2, MPEG-4, AAC, and ATRAC, and is extensible to support manufacturer-defined codecs, such as apt-X. Some Bluetooth stacks enforce the SCMS-T digital rights management (DRM) scheme. In these cases, it is impossible to connect certain A2DP headphones for high quality audio.


Making bluetooth-audio sound great

The audio quality of a Bluetooth device depends on several factors, including what parameters are used while implementing the A2DP profile, how well the product is designed, and the quality of materials used in the device.

When engineers add Bluetooth technology to their devices, they have a choice of how to implement the Bluetooth audio specification. They can choose a high bit rate for the best audio quality or a lower bit rate to save on manufacturing costs. We allow some flexibility in the implementation in order to allow companies to produce products at different price points.


Bluetooth: Sufficient fidelity even for average listeners?

Bluetooth A2DP has a maximum available bandwidth of 768 kbps. So, audio compression is necessary to deliver two-channel digital-stereo sound. Myriad compression technologies are currently available, each targeting and offering benefits in specific applications. However, most of them derive from two fundamental audio-compression processes: perceptual techniques based on psychoacoustic models of hearing and predictive techniques, which as their name implies, employ a system of predictive coding. They are therefore known as ADPCM (adaptive-differential-pulse-code-modulation) codecs.

Generally, the higher the compression ratio, the more audio content you lose. With perceptual codecs, such as MP3, AAC, and their derivatives, analysis of the frequency spectrum results in the removal of any content the technology deems imperceptible to the human ear. This technique requires buffering of an audio sample of approximately 512 bytes to perform the analysis. Buffering is often the fundamental source of coding delay. The complexity of the audio can also affect the delay of the encoding process. The psychoacoustic procedure, with its ability to produce high compression ratios and retain reasonably high audio quality, is processor-intensive and therefore not a good approach for power-efficient, battery-powered devices.

ADPCM codecs operate in a different manner, due to their unique characteristics. PCM is the digital representation of an analog signal, wherein regular sampling of the signal magnitude at uniform levels results in quantization to a series of symbols in a digital code. CDs are examples of the implementation of PCM audio. ADPCM involves audio-value encoding as the difference between the current and the previous values, and the quantization step size varies to allow a bandwidth reduction for a given SNR (signal-to-noise ratio).

The ideal scenario for many consumer-electronic and mobile-device companies would be to use Bluetooth and provide full-bandwidth stereo-audio-quality streaming in real time. Only a few companies currently provide products to fulfill this need. Given the issues regarding using psychoacoustic algorithms, you should discount MP3 as a viable technology for wireless transfers. Therefore, you must look at ADPCM-based alternatives. US-based Open Interface North America, for example, in 2003 launched Soundabout eSBC (Enhanced SBC). Based on the same principles as SBC, eSBC allows a 510-kbps data rate and, hence, some quality benefit. However, this higher data rate comes at the expense of power consumption, which can have a significant impact on battery life, and the algorithm offers no latency improvement.


An introduction to computer audio - Bluetooth

Bluetooth - Bluetooth is a protocol allowing low power devices to communicate wireless. With a nominal bandwidth of 3 Mbit/s (2.1 + EDR) it is not suit for bit perfect audio. Due to this limitation it is not possible to send CD quality audio (16 bits/44.1 kHz) over Bluetooth without applying lossy compression.

A2DP - Most of the time the A2DP (Advanced Audio Distribution Profile) protocol is used for audio.This profile limits the available maximum bit rate to 320kb/s for mono, and 512kb/s for two-channel modes. It support the following Codecs:
- SBC (subband codec) is mandatory.
- MPEG-1,2 Audio
- MPEG-2,4 AAC
- ATRAC (Sony)
In essence high bit rate MP3 but vendors can implement their own protocols.

APT-X - A proprietary codec by CSR. As it is not a mandatory part of the standard you need both a sender and a receiver supporting this protocol. It is a lossy protocol but said to improve sound quality compared with SBC:
- Compression ratio: 4:1
- Word depth: 16, 20 or 24-bit audio supported
- Data rates: 60 kbps to 576kbps(16-bit 15kHz mono to 24-bit 48kHz stereo)
- Frequency response: 10Hz to 24kHz
- Delay: <1.89ms @ Fs 48KHz
- Dynamic range: 16-bit>92dB, 20-bit>112dB, 24-bit>120dB
- THD+N: -81.1dB (0.008%) (24-bit)
- Sample frequencies: 0-48kHz
- Auxiliary data: Embedded, sample rate dependent up to 1/4 Fs kbps
- AutoSync: Can re-establish connection in 5ms
- Bit error resilience: Up to 1:10,000

[Coach-Z]

Jeg har en Argon BT2, som vel egentlig er sin egen DAC, den konverterer i hvert fald et digitalt Apt-X signal om til analog phono ud, eller den kan opsample det til 24/192 til en ekstern dac via optisk ud.

http://www.hifiklubben.dk/Products/argo ... ver-62662/

Forstår ikke helt teknikken, men det kan vel lade sig gøre. Problemet er, hvis det er er et problem, at Apt-X max er 24/48 og det må derfor være max for en evt. dac med bluetooth indbygget, medmindre bluetooth chippen selv opsampler, som min gør.


Dette er mit gæt, ikke noget jeg er sikker på

EDIT:

Dette er kun gældende for AptX Lossless og ikke almindelig AptX... jeg kan dog ikke finde nogen AptX Lossless apparater endnu desværre

http://en.wikipedia.org/wiki/AptX#aptX_Lossless

aptX Lossless supports high-definition audio up to 96 kHz sampling rates and sample resolutions up to 24 bits. The codec optionally permits a "hybrid" coding scheme for applications where average and/or peak compressed data rates must be capped at a constrained level. This involves the dynamic application of a form of "near lossless" coding – but only for those short sections of audio where completely lossless coding cannot respect the bandwidth constraints. Even for those short periods while the "near lossless" coding is active, high-definition audio quality is maintained, retaining audio frequencies up to 20 kHz and a dynamic range of at least 120 dB.
Coding latency is another scalable parameter within aptX Lossless and can be dynamically traded against other parameters such as levels of compression and computational complexity. The latency of the aptX Lossless codec can be scaled to as low as 1 ms for 48 kHz sampled audio, depending on the settings of other configurable parameters. aptX Lossless performs particularly well against other lossless codecs when the coding latency is constrained to be small, such as 5 ms or less, making it particularly appropriate for delay-sensitive interactive audio applications.
Many lossless codecs possess a low computational overhead compared to well-known lossy codecs, such as MP3 and AAC. This is particularly important for deeply embedded audio applications running on low-power mobile devices. aptX Lossless promotes low computational overhead by dynamically selecting the simplest coding functions for each short segment of audio whilst complying with other operational constraints, such as levels of compression and coding delay. Depending on the settings of other scalable parameters, aptX Lossless can encode a 48 kHz 16-bit stereo audio stream using only 10 MIPS on a modern RISC processor with signal processing extensions. The corresponding decoder represents only 6 MIPS on the same platform.
User metadata and special synchronization data can be incorporated into the compressed format at configurable rates. The latter permits rapid decoder resynchronization in the event of data corruption or loss over communications links where Quality of Service (QoS) can vary rapidly. Depending on the settings of parameters, decoder resynchronization can occur within 1-2 ms

[vaskebjørnen]

Jeg har en Belkin Bluetooth reciever med Optisk og Coax output samt NFC den fungere rigtig fint

[MadsM]

Er der nogen af jer der har prøvet Noozxoide EZIO rewire Pro?

[vaskebjørnen]

Er der nogen af jer der har prøvet Noozxoide EZIO rewire Pro?

Nix det crasher på min sgs3 lte

Sendt fra min GT-I9305 med Tapatalk

[Sorensiim]

Hvis I har XBMC kørende så skal I have denne app: https://play.google.com/store/apps/deta ... remotebeta

For HULAN det er godt! Lige pludselig har XBMC et interface på lækkerhedsniveau med f.eks. Sonos, samtidig med at din normale remote stadig kan betjene grejet.

[Psymon]

Du kan også kigge på Yatse

https://play.google.com/store/apps/deta ... widgetfree

virkelig en lækker app

[Niels]

Kan der anvises en (den) guide til at roote Nexus7 4.4 og tilsvarende MOTO G med henblik på at kunne anvende externt usblager og evt. dac ?

/Niels

[Henrik_sdk]

Stikker lige en føler frem, hvis jeg skulle overgå fra ios, hvilken telefon skal jeg kigge på nu og de næste 3-4 måneder. nfc, stor skærm og billig uden abbonement helst..

[odderen]

Stikker lige en føler frem, hvis jeg skulle overgå fra ios, hvilken telefon skal jeg kigge på nu og de næste 3-4 måneder. nfc, stor skærm og billig uden abbonement helst..

Hvor billig snakker vi om her?

Sendt fra min galaxy Note 3 med tapatalk classic

[Niels]

MOTO G

Stikker lige en føler frem, hvis jeg skulle overgå fra ios, hvilken telefon skal jeg kigge på nu og de næste 3-4 måneder. nfc, stor skærm og billig uden abbonement helst..

[Anda]

MOTO G

Ingen NFC

[Niels]

My bad, sorry.


Sendt fra min Nexus 7 med Tapatalk

[Henrik_sdk]

2-3000 kr, har ikke noget imod samsung andet at jeg har hørt det ligger mange ting på telefonen så der ikke er så meget plads tilbage. Men der er jo snart mobile world congress, så kommer der helt sikkert en masse nyt spændende.

[vaskebjørnen]

2-3000 kr, har ikke noget imod samsung andet at jeg har hørt det ligger mange ting på telefonen så der ikke er så meget plads tilbage. Men der er jo snart mobile world congress, så kommer der helt sikkert en masse nyt spændende.

Jeg har en galaxy s3 lte, den fungere rigtig fint har nfc og fornuftig størrelse skærm synes jeg. Der skal bare lige deaktiveres lidt programmer til at starte med på den

Sendt fra min GT-I9305 med Tapatalk