Vim yog qhov loj ntawm cov xov tooj smartphones tsis muaj 3.5 hli audio jack, wireless Bluetooth headphones tau dhau los ua txoj hauv kev rau ntau tus mloog nkauj thiab sib txuas lus hauv lub mloog pob ntseg.
Cov neeg tsim khoom ntawm cov khoom siv wireless tsis tas yuav sau cov ncauj lus kom ntxaws txog cov khoom lag luam, thiab cov lus hais txog Bluetooth audio hauv Is Taws Nem yog qhov tsis sib xws, qee zaum tsis raug, tsis txhob tham txog tag nrho cov yam ntxwv, thiab feem ntau luam tawm tib cov ntaub ntawv uas tsis sib haum nrog kev muaj tiag.
Cia peb sim nkag siab txog cov txheej txheem, lub peev xwm ntawm Bluetooth OS pawg, lub mloog pob ntseg thiab hais lus, Bluetooth codecs rau suab paj nruag thiab hais lus, nrhiav seb dab tsi cuam tshuam rau qhov zoo ntawm cov suab thiab latency, kawm paub sau thiab txiav txim siab cov ntaub ntawv hais txog kev txhawb nqa codecs thiab lwm yam khoom siv. peev xwm.

TL; DR:

• SBC - normal codec
• Lub mloog pob ntseg muaj lawv tus kheej sib npaug thiab tom qab ua tiav rau txhua tus codec nyias
• aptX tsis zoo li kev tshaj tawm
• LDAC yog kev lag luam bullshit
• Hu zoo tseem tsis zoo
• Koj tuaj yeem embed C audio encoders rau hauv koj lub browser los ntawm kev sau lawv rau hauv WebAssembly ntawm emscripten, thiab lawv yuav tsis qeeb ntau.

Suab paj nruag ntawm Bluetooth

Lub luag haujlwm tseem ceeb ntawm Bluetooth yog txiav txim siab los ntawm cov profiles - cov lus qhia tshwj xeeb ntawm cov haujlwm tshwj xeeb. Bluetooth suab paj nruag streaming siv qhov zoo tshaj plaws A2DP unidirectional audio kis profile. Tus qauv A2DP tau txais kev pom zoo hauv xyoo 2003 thiab tsis tau hloov pauv loj txij thaum ntawd los.
Hauv qhov profile, 1 qhov yuav tsum tau codec ntawm kev siv qis qis SBC, tsim tshwj xeeb rau Bluetooth, thiab 3 qhov ntxiv yog tus qauv. Nws tseem tuaj yeem siv cov codecs tsis muaj ntaub ntawv ntawm koj tus kheej siv.

Txog rau lub Rau Hli 2019 peb yog hauv xkcd nrog 14 A2DP codecs:

• SBC ← tus qauv hauv A2DP, txhawb nqa los ntawm txhua yam khoom siv
• MPEG-1/2 Layer 1/2/3 ← standardized hauv A2DP: paub zoo MP3, siv hauv digital TV MP2, thiab tsis paub MP1
• MPEG-2/4 AAC ← standardized hauv A2DP
• ATTRAC ← qub codec los ntawm Sony, tus qauv hauv A2DP
• LDAC ← Tshiab codec los ntawm Sony
• ua aptX ← codec los ntawm 1988
• aptX HD tau ← tib yam li aptX, tsuas yog muaj cov kev xaiv encoding sib txawv
• aptX Tsis Muaj Tsawg ← sib txawv kiag li codec, tsis muaj software siv
• aptX Haum ← lwm codec los ntawm Qualcomm
• FastStream ← pseudo codec, bidirectional SBC hloov kho
• HWM LHDC ← Tshiab codec los ntawm Huawei
• Samsung HD ← txhawb los ntawm 2 pab kiag li lawm
• Samsung Scalable ← txhawb los ntawm 2 pab kiag li lawm
• Samsung UHQ-BT ← txhawb los ntawm 3 pab kiag li lawm

Vim li cas peb thiaj xav tau codecs txhua, koj nug, thaum Bluetooth muaj EDR, uas tso cai rau koj hloov cov ntaub ntawv ntawm speeds ntawm 2 thiab 3 Mbit / s, thiab rau uncompressed ob-channel 16-ntsis PCM, 1.4 Mbit / s yog txaus?

Hloov cov ntaub ntawv ntawm Bluetooth

Muaj ob hom kev hloov ntaub ntawv hauv Bluetooth: Asynchronous Connection Less (ACL) rau kev hloov pauv asynchronous yam tsis muaj kev sib txuas, thiab Synchronous Connection Oriented (SCO), rau synchronous hloov nrog kev sib tham ua ntej.
Kev xa tawm yog nqa tawm siv lub sijhawm faib cov phiaj xwm thiab xaiv cov kab sib kis rau txhua pob ntawv sib cais (Frequency-Hop/Time-Division-Duplex, FH/TDD), rau lub sijhawm twg yog muab faib ua 625-microsecond intervals hu ua slots. Ib qho ntawm cov khoom siv xa mus rau hauv cov lej sib npaug, lwm qhov hauv cov lej khib. Cov pob ntawv kis tau tuaj yeem tuav 1, 3 lossis 5 qhov, nyob ntawm qhov loj ntawm cov ntaub ntawv thiab cov txheej txheem sib kis, qhov no, kev sib kis los ntawm ib lub cuab yeej yog nqa tawm hauv qhov sib npaug thiab khib nyiab kom txog thaum kawg ntawm kev sib kis. Nyob rau hauv tag nrho, mus txog 1600 pob ntawv tuaj yeem tau txais thiab xa tawm ib ob, yog tias lawv txhua tus nyob hauv 1 qhov, thiab ob qho tib si kis tau thiab tau txais ib yam dab tsi tsis nres.

2 thiab 3 Mbit / s rau EDR, uas tuaj yeem pom hauv kev tshaj tawm thiab hauv lub vev xaib Bluetooth, yog qhov siab tshaj plaws channel hloov pauv tus nqi ntawm tag nrho cov ntaub ntawv hauv tag nrho (suav nrog cov ntsiab lus ntawm txhua cov txheej txheem uas cov ntaub ntawv yuav tsum tau ntim), hauv ob qho kev qhia ib txhij. Cov ntaub ntawv tseeb hloov ceev yuav sib txawv heev.

Txhawm rau xa cov suab paj nruag, siv txoj kev asynchronous, yuav luag txhua zaus siv cov pob ntawv xws li 2-DH5 thiab 3-DH5, uas nqa cov ntaub ntawv ntau tshaj plaws hauv EDR hom ntawm 2 Mbit / s thiab 3 Mbit / s, raws li, thiab nyob 5 lub sijhawm. - sib koom slots.

Schematic sawv cev ntawm kev sib kis siv 5 qhov los ntawm ib lub cuab yeej thiab 1 qhov los ntawm lwm qhov (DH5 / DH1):


Vim yog lub hauv paus ntsiab lus ntawm lub sij hawm faib ntawm cov huab cua, peb raug yuam kom tos ib lub sij hawm 625-microsecond tom qab kis ib pob ntawv yog tias lub thib ob ntaus ntawv tsis kis ib yam dab tsi rau peb los yog kis tau ib pob ntawv me me, thiab ntau lub sij hawm yog hais tias tus thib ob ntaus ntawv kis tau tus mob. hauv pob ntawv loj. Yog tias muaj ntau tshaj ib lub cuab yeej txuas nrog lub xov tooj (piv txwv li, lub mloog pob ntseg, watches thiab lub kauj-toog npab), ces lub sijhawm hloov mus yog sib koom ntawm txhua tus ntawm lawv.

Qhov yuav tsum tau encapsulate suab nyob rau hauv tshwj xeeb thauj raws tu qauv L2CAP thiab AVDTP yuav siv sij hawm 16 bytes los ntawm qhov ua tau siab tshaj plaws ntawm kis tau tus mob lub payload.

Hom pob
Tus naj npawb ntawm qhov qhib
Max. tus naj npawb ntawm bytes hauv pob ntawv
Max. tus lej ntawm bytes ntawm A2DP payload
Max. A2DP them nyiaj bitrate

2-DH3
3
367
351
936 kbps

3-DH3
3
552
536
1429 kbps

2-DH5
5
679
663
1414 kbps

3-DH5
5
1021
1005
2143 kbps

1414 thiab 1429 kbps yog twv yuav raug hu tsis txaus los xa cov suab tsis sib xws hauv cov xwm txheej tiag tiag, nrog lub suab nrov 2.4 GHz ntau yam thiab xav tau xa cov ntaub ntawv pabcuam. EDR 3 Mbit / s xav tau ntawm kev xa xov hluav taws xob thiab suab nrov ntawm huab cua, yog li ntawd, txawm tias nyob rau hauv 3-DH5 hom, kev sib kis ntawm PCM tsis yooj yim sua, yuav muaj kev cuam tshuam luv luv, thiab txhua yam tsuas yog ua haujlwm ntawm qhov deb ntawm ib qho. ob peb meters.
Hauv kev xyaum, txawm tias 990 kbit / s suab kwj (LDAC 990 kbit / s) yog qhov nyuaj rau kev xa tawm.

Cia peb rov qab mus rau codecs.

SBC

Codec xav tau rau txhua yam khoom siv uas txhawb nqa tus qauv A2DP. Qhov zoo tshaj plaws thiab phem tshaj codec tib lub sijhawm.

Sampling zaus
Ntsis qhov tob
Tus nqi
Kev them nyiaj yug encoding
Kev them nyiaj yug decoding

16, 32, 44.1, 48 kHz
16 ntsis
10-1500 kbps
Txhua yam khoom siv
Txhua yam khoom siv

SBC yog ib qho yooj yim thiab siv tau yooj yim codec, nrog rau tus qauv psychoacoustic primitive (tsuas yog siv lub ntsej muag ntawm lub suab ntsiag to), siv adaptive pulse code modulation (APCM).
Qhov tshwj xeeb A2DP pom zoo rau ob qhov profile rau kev siv: Middle Quality thiab High Quality.


Lub codec muaj ntau qhov chaw uas tso cai rau koj los tswj lub algorithmic ncua, tus naj npawb ntawm cov qauv nyob rau hauv ib lub block, me ntsis faib algorithm, tab sis yuav luag txhua qhov chaw tib yam tsis pom zoo nyob rau hauv cov specification yog siv: Joint Stereo, 8 zaus bands, 16 blocks nyob rau hauv. ib lub suab ncej, Loudness me ntsis faib txoj kev.
SBC txhawb kev hloov pauv hloov pauv ntawm Bitpool parameter, uas cuam tshuam ncaj qha rau tus nqi qis. Yog hais tias cov airwaves raug kaw, pob ntawv ploj, lossis cov khoom siv nyob ntawm qhov deb, lub suab yuav txo tau Bitpool kom txog thaum kev sib txuas lus rov zoo li qub.

Feem ntau lub mloog pob ntseg manufacturers teeb qhov siab tshaj plaws Bitpool tus nqi mus rau 53, uas txwv qhov bitrate rau 328 kilobits ib ob thaum siv cov lus pom zoo.
Txawm hais tias cov chaw tsim khoom siv lub mloog pob ntseg tau teeb tsa tus nqi siab tshaj Bitpool siab tshaj 53 (cov qauv zoo li no pom, piv txwv li: Beats Solo³, JBL Everest Elite 750NC, Apple AirPods, kuj pom ntawm qee lub receivers thiab lub taub hau tsheb), ces feem ntau OS yuav tsis tso cai. kev siv cov bitrates nce ntxiv vim teeb tsa tus nqi sab hauv hauv Bluetooth pawg.
Tsis tas li ntawd, qee cov tuam txhab tsim cov nqi qis tshaj Bitpool rau qee cov khoom siv. Piv txwv li, rau Bluedio T nws yog 39, rau Samsung IconX nws yog 37, uas muab suab tsis zoo.

Cov kev txwv dag ntawm ib feem ntawm cov neeg tsim khoom ntawm Bluetooth pawg feem ntau yuav tshwm sim vim qhov tsis sib haum xeeb ntawm qee cov khoom siv nrog cov txiaj ntsig loj Bitpool lossis atypical profiles, txawm tias lawv tau tshaj tawm txog kev txhawb nqa rau lawv, thiab tsis txaus kuaj thaum muaj ntawv pov thawj. Nws yog qhov yooj yim dua rau cov kws sau ntawv ntawm Bluetooth pawg txhawm rau txwv lawv tus kheej kom pom zoo ntawm qhov profile pom zoo, tsis yog tsim cov ntaub ntawv ntawm cov khoom siv tsis raug (txawm tias tam sim no lawv ua qhov no rau lwm yam haujlwm tsis raug).

SBC dynamically faib quantization bits rau zaus bands nyob rau hauv qis-rau-siab, nrog rau qhov hnyav sib txawv. Yog tias tag nrho cov bitrate tau siv rau qhov qis thiab nruab nrab zaus, qhov siab zaus yuav raug "txiav tawm" (yuav muaj qhov ntsiag to xwb).

Piv txwv li SBC 328 kbps. Nyob rau sab saum toj yog qhov qub, hauv qab yog SBC, hloov pauv ntawm cov lem. Lub suab hauv cov ntaub ntawv video siv FLAC lossless compression codec. Siv FLAC hauv ib lub thawv mp4 tsis yog tus qauv tsim, yog li nws tsis tau lees tias koj tus browser yuav ua si, tab sis nws yuav tsum ua haujlwm hauv qhov tseeb versions ntawm desktop Chrome thiab Firefox. Yog tias koj tsis muaj lub suab, koj tuaj yeem rub tawm cov ntaub ntawv thiab qhib nws hauv lub tshuab ua yeeb yaj kiab puv puv.
ZZ Sab saum toj - Tus txiv neej hnav ris tsho

Lub spectrogram qhia tau hais tias lub sijhawm hloov pauv: SBC ib ntus txiav cov suab ntsiag to saum 17.5 kHz, thiab tsis faib ib qho me me rau txhua qhov band saum 20 kHz. Tag nrho cov spectrogram muaj los ntawm nias (1.7 MB).

Kuv tsis hnov ​​qhov txawv ntawm tus thawj thiab SBC ntawm txoj kab no.

Cia peb ua ib yam dab tsi tshiab thiab simulate lub suab uas yuav tau txais siv Samsung Gear IconX headphones nrog Bitpool 37 (saum toj no - thawj lub teeb liab, hauv qab no - SBC 239 kbps, suab hauv FLAC).
Mob Siab Rau Tus Kheej - Ua tim khawv

Kuv hnov ​​​​ntxhiab, tsis tshua muaj suab nrov thiab lub suab tsis zoo "clunking" hauv cov suab nrov nrov.

Txawm hais tias SBC yog cov codec hloov tau yooj yim, nws tuaj yeem teeb tsa rau qis latency, muab lub suab zoo ntawm cov bitrates siab (452+ kbps) thiab zoo heev rau cov neeg feem coob ntawm tus qauv High Quality (328 kbps), vim qhov tseeb tias A2DP tus qauv tsis qhia meej cov ntaub ntawv ruaj khov (tab sis tsuas yog muab cov lus pom zoo), pawg neeg tsim khoom tau teeb tsa kev txwv tsis pub siv rau Bitpool, qhov tsis sib xws ntawm cov suab sib kis tsis tau tshwm sim hauv cov neeg siv interface, thiab lub mloog pob ntseg tsim teeb tsa lawv tus kheej thiab yeej tsis. qhia txog tus nqi Bitpool nyob rau hauv cov kev specifications ntawm cov khoom, codec los ua nto moo rau nws cov suab tsis zoo, txawm hais tias qhov no tsis yog ib qho teeb meem nrog lub codec xws li.
Bitpool parameter ncaj qha cuam tshuam cov bitrate nkaus xwb nyob rau hauv ib qhov profile. Tib Bitpool 53 tus nqi tuaj yeem muab ob qho tib si bitrate ntawm 328 kbps nrog cov lus pom zoo High Quality profile, thiab 1212 kbps nrog Dual Channel thiab 4 zaus bands, uas yog vim li cas cov neeg sau ntawv OS, ntxiv rau kev txwv ntawm Bitpool, teeb tsa kev txwv thiab rau Bitrate. Raws li kuv pom nws, qhov xwm txheej no tshwm sim vim muaj qhov tsis zoo hauv A2DP tus qauv: nws yog qhov tsim nyog los sib tham txog tus nqi, tsis yog Bitpool.

Cov lus txhawb nqa rau SBC muaj peev xwm hauv OS sib txawv:

OS
Txhawb nqa tus nqi piv txwv
Limit max. Bitpool
Limit max. Bitrate
Yam Bitrate
Bitpool dynamic hloov

lub qhov rais 10
44.1 кГц
53
512 kbps
328 kbps
✓*

Linux (BlueZ + PulseAudio)
16, 32, 44.1, 48 kHz
64 (rau kev sib txuas nkag), 53 (rau kev sib txuas tawm)
Tsis txwv
328 kbps
✓*

macOS High Sierra
44.1 кГц
64, default 53 ***
Tsis paub
328 kbps
✗

Hauv 4.4-9
44.1 / 48 kHz
53
328 kbps
328 kbps
✗

Hauv 4.1-4.3.1
44.1, 48 kHz
53
229 kbps
229 kbps
✗

Blackberry OS 10
48 кГц
53
Tsis txwv
328 kbps
✗

* Bitpool tsuas yog txo qis, tab sis tsis nce ntxiv, yog tias hloov pauv cov xwm txheej zoo dua. Txhawm rau rov qab Bitpool koj yuav tsum tau tso tseg playback, tos ob peb lub vib nas this thiab pib lub suab dua.
** Lub neej ntawd tus nqi nyob ntawm pawg teeb tsa tau teev tseg thaum sau cov firmware. Hauv Android 8/8.1 zaus tsuas yog 44.1 kHz lossis 48 kHz, nyob ntawm qhov chaw thaum muab tso ua ke, hauv lwm cov qauv 44.1 kHz thiab 48 kHz tau txais kev txhawb nqa ib txhij.
*** Tus nqi Bitpool tuaj yeem nce ntxiv hauv Bluetooth Explorer program.

aptX thiab aptX HD

aptX yog ib qho yooj yim thiab suav ceev codec, tsis muaj psychoacoustics, siv adaptive sib txawv mem tes code modulation (ADPCM). tshwm sim nyob ib ncig ntawm 1988 (daim ntawv teev npe patent hnub tim Lub Ob Hlis 1988), ua ntej Bluetooth, nws tau siv feem ntau hauv cov khoom siv suab wireless. Tam sim no muaj los ntawm Qualcomm, yuav tsum muaj ntawv tso cai thiab muaj nuj nqis. Raws li xyoo 2014: $ 6000 ib zaug thiab ≈ $ 1 rau ib lub cuab yeej, rau cov khoom siv ntau txog 10000 (qhov chaw, p. 16).
aptX thiab aptX HD yog tib codec, nrog sib txawv encoding profiles.

Lub codec muaj tsuas yog ib qho parameter - xaiv qhov sampling zaus. Txawm li cas los xij, muaj kev xaiv ntawm tus lej / hom ntawm cov channel, tab sis hauv txhua yam khoom siv paub rau kuv (70+ daim) tsuas yog Stereo tau txais kev txhawb nqa.

Codec
Sampling zaus
Ntsis qhov tob
Tus nqi
Kev them nyiaj yug encoding
Kev them nyiaj yug decoding

ua aptX
16, 32, 44.1, 48 kHz
16 ntsis
128 / 256 / 352 / 384 kbps (nyob ntawm tus lej ntsuas)
Windows 10 (desktop thiab mobile), macOS, Android 4.4+/7*, Blackberry OS 10
Ntau yam ntawm cov khoom siv suab (hardware)

* Versions mus txog 7 yuav tsum tau hloov kho ntawm Bluetooth pawg. Lub codec tsuas yog txhawb nqa yog tias lub chaw tsim khoom siv Android tau tso cai codec los ntawm Qualcomm (yog tias OS muaj cov tsev qiv ntawv encoding).

aptX faib suab rau hauv 4 zaus bands thiab quantizes lawv nrog tib tus lej ntawm cov khoom tas li: 8 khoom rau 0-5.5 kHz, 4 khoom rau 5.5-11 kHz, 2 khoom rau 11-16.5 kHz, 2 khoom rau 16.5-22 kHz ( Cov duab rau cov piv txwv 44.1 kHz).

Piv txwv ntawm aptX suab (nyob rau sab saum toj - thawj lub teeb liab, hauv qab - aptX, spectrograms ntawm tsuas yog sab laug, suab hauv FLAC):

Qhov siab dhau los ua me ntsis redder, tab sis koj tsis hnov ​​​​qhov txawv.

Vim yog qhov kev faib khoom ruaj khov ntawm cov khoom siv quantization, tus codec tsis tuaj yeem "hloov cov khoom" rau cov zaus uas xav tau lawv tshaj plaws. Tsis zoo li SBC, aptX yuav tsis "txiav" zaus, tab sis yuav ntxiv quantization nrov rau lawv, txo cov dynamic ntau ntawm lub suab.

Nws yuav tsum tsis txhob xav tias siv, piv txwv li, 2 cov khoom ib pawg txo cov dynamic ntau rau 12 dB: ADPCM tso cai rau 96 dB ntawm dynamic ntau yam txawm tias thaum siv 2 quantization khoom, tab sis tsuas yog rau ib qho teeb meem xwb.
ADPCM khaws cov lej sib txawv ntawm cov qauv tam sim no thiab cov qauv tom ntej, es tsis txhob khaws tus nqi kiag li hauv PCM. Qhov no tso cai rau koj los txo cov kev xav tau ntawm cov khoom siv uas yuav tsum tau khaws cia tib yam (tsis muaj kev poob) lossis yuav luag tib yam (nrog rau qhov yuam kev me me) cov ntaub ntawv. Txhawm rau txo qhov yuam kev sib npaug, cov lus coefficient yog siv.
Thaum tsim cov codec, cov kws sau ntawv suav ADPCM coefficients ntawm cov ntaub ntawv suab paj nruag. Qhov ze dua lub teeb liab suab yog rau cov suab paj nruag uas cov ntxhuav tau tsim, qhov tsawg dua qhov yuam kev (suab nrov) aptX tsim.

Vim li no, kev ntsuam xyuas hluavtaws yuav ib txwm ua rau cov txiaj ntsig tsis zoo dua li suab paj nruag. Kuv ua ib qho piv txwv tshwj xeeb hluavtaws uas aptX qhia cov txiaj ntsig tsis zoo - sine yoj nrog zaus ntawm 12.4 kHz (saum toj no - thawj lub teeb liab, hauv qab - aptX. Suab hauv FLAC. Txo lub ntim!):

Spectrum duab:


Cov suab nrov yog pom meej.

Txawm li cas los xij, yog tias koj tsim lub sine yoj nrog lub amplitude me kom nws nyob ntsiag to, lub suab nrov kuj yuav ua ntsiag to, qhia txog ntau yam dynamic:

Txhawm rau hnov ​​​​qhov sib txawv ntawm cov suab paj nruag thawj zaug thiab cov compressed ib qho, koj tuaj yeem hloov pauv ib qho ntawm cov cim thiab ntxiv cov lem los ntawm cov channel. Txoj hauv kev no yog, feem ntau, tsis raug, thiab yuav tsis muab cov txiaj ntsig zoo nrog ntau cov codecs, tab sis tshwj xeeb rau ADPCM nws yog qhov tsim nyog heev.
Qhov txawv ntawm thawj thiab aptX
Lub hauv paus txhais tau tias square qhov sib txawv ntawm cov teeb liab yog nyob rau theem ntawm -37.4 dB, uas tsis ntau rau cov suab paj nruag compressed.

aptX HD tau

aptX HD tsis yog ib leeg codec - nws yog ib qho kev txhim kho encoding profile ntawm aptX codec. Cov kev hloov pauv cuam tshuam rau tus lej ntawm cov khoom siv rau kev nkag siab ntau zaus: 10 khoom rau 0-5.5 kHz, 6 khoom rau 5.5-11 kHz, 4 khoom rau 11-16.5 kHz, 4 khoom rau 16.5-22 kHz (tus lej rau 44.1 kHz). .

Codec
Sampling zaus
Ntsis qhov tob
Tus nqi
Kev them nyiaj yug encoding
Kev them nyiaj yug decoding

aptX HD tau
16, 32, 44.1, 48 kHz
24 bits
192 / 384 / 529 / 576 kbps (nyob ntawm tus lej ntsuas)
Android 8+*
Qee cov khoom siv suab (hardware)

* Versions mus txog 7 yuav tsum tau hloov kho ntawm Bluetooth pawg. Lub codec tsuas yog txhawb nqa yog tias lub chaw tsim khoom siv Android tau tso cai codec los ntawm Qualcomm (yog tias OS muaj cov tsev qiv ntawv encoding).

Tsawg dua li aptX: pom tau tias yuav tsum muaj ntawv tso cai cais los ntawm Qualcomm, thiab cais cov nqi ntawv tso cai.

Cia peb rov ua qhov piv txwv nrog sine yoj ntawm 12.4 kHz:


Ntau yam zoo dua li aptX, tab sis tseem muaj suab nrov me ntsis.

aptX Tsis Muaj Tsawg

Lub codec los ntawm Qualcomm uas tsis muaj dab tsi sib xws nrog tus qauv aptX thiab aptX HD, txiav txim siab los ntawm cov ntaub ntawv txwv los ntawm cov neeg koom nrog hauv nws txoj kev loj hlob. Tsim los rau kev sib tham sib qis-latency suab kis tau tus mob (movies, games), qhov twg lub suab ncua tsis tuaj yeem hloov kho los ntawm software. Tsis muaj kev paub txog kev siv software ntawm encoders thiab decoders; lawv tau txais kev txhawb nqa tshwj xeeb los ntawm transmitters, receivers, headphones thiab speaker, tab sis tsis yog los ntawm smartphones thiab computers.

Sampling zaus
Tus nqi
Kev them nyiaj yug encoding
Kev them nyiaj yug decoding

44.1 кГц
276/420 kbps
Qee qhov transmitters (hardware)
Qee cov khoom siv suab (hardware)

AAC

AAC, los yog Advanced Audio Coding, yog ib qho kev sib txuas lus nyuaj nrog tus qauv psychoacoustic loj. Dav siv rau lub suab hauv Is Taws Nem, thib ob hauv kev muaj koob npe tom qab MP3. Yuav tsum tau daim ntawv tso cai thiab cov nuj nqis: $ 15000 ib zaug (lossis $ 1000 rau cov tuam txhab uas muaj tsawg dua 15 tus neeg ua haujlwm) + $ 0.98 rau thawj 500000 khoom siv (qhov chaw).
Lub codec yog standardized nyob rau hauv lub MPEG-2 thiab MPEG-4 specifications, thiab contrary to common misconception, nws tsis belongs rau kua.

Sampling zaus
Tus nqi
Kev them nyiaj yug encoding
Kev them nyiaj yug decoding

8-96 kHz
8 - 576 kbps (rau lub tso suab), 256 - 320 kbps (ib txwm rau Bluetooth)
macOS, Android 7+*, iOS
Ntau yam ntawm cov khoom siv suab (hardware)

* tsuas yog ntawm cov khoom siv uas cov tuam ntxhab tau them cov nqi ntawv tso cai

iOS thiab macOS siv Apple qhov zoo tshaj plaws AAC encoder tam sim no kom xa tau lub suab zoo tshaj plaws. Android siv qhov thib ob-siab tshaj plaws Fraunhofer FDK AAC encoder, tab sis tej zaum yuav siv ntau yam kho vajtse tsim rau hauv lub platform (SoC) uas tsis paub encoding zoo. Raws li kev ntsuam xyuas tsis ntev los no ntawm SoundGuys lub vev xaib, qhov zoo ntawm AAC encoding sib txawv heev ntawm cov xov tooj Android sib txawv:

Cov khoom siv wireless feem ntau muaj qhov siab tshaj plaws ntawm 320 kbps rau AAC, qee qhov tsuas yog txhawb 256 kbps. Lwm cov bitrates tsis tshua muaj heev.
AAC muab qhov zoo tshaj plaws ntawm 320 thiab 256 kbps bitrates, tab sis raug rau poob ntawm sequential encoding ntawm twb compressed cov ntsiab lusTxawm li cas los xij, nws yog qhov nyuaj rau hnov ​​​​txog qhov sib txawv nrog cov thawj ntawm iOS no ntawm tus nqi ntawm 256 kbps txawm tias muaj ntau qhov kev sib txuas ua ke; nrog rau ib qho encoding, piv txwv li, MP3 320 kbps rau AAC 256 kbps, kev poob tuaj yeem tsis quav ntsej.
Raws li nrog rau lwm yam Bluetooth codecs, tej suab paj nruag yog thawj zaug decoded thiab ces encoded los ntawm lub codec. Thaum mloog cov nkauj hauv AAC hom ntawv, nws yog thawj zaug txiav txim siab los ntawm OS, tom qab ntawd nkag mus rau hauv AAC dua rau kev sib kis ntawm Bluetooth. Qhov no yog qhov tsim nyog rau kev sib xyaw ntau lub suab, xws li suab paj nruag thiab cov ntawv ceeb toom tshiab. iOS no tsis muaj kev zam. Hauv Is Taws Nem koj tuaj yeem pom ntau nqe lus hais tias ntawm iOS suab paj nruag hauv AAC hom tsis tau hloov pauv thaum kis ntawm Bluetooth, uas tsis muaj tseeb.

MP1/2/3

Cov codecs ntawm MPEG-1/2 Part 3 tsev neeg muaj cov paub zoo thiab siv dav MP3, tsawg dua MP2 (siv feem ntau hauv TV thiab xov tooj cua), thiab MP1 tsis paub meej.

Cov laus MP1 thiab MP2 codecs tsis txaus siab rau tag nrho: Kuv nrhiav tsis tau tej lub mloog pob ntseg lossis Bluetooth pawg uas yuav encode lossis txiav txim siab rau lawv.
MP3 decoding tau txais kev txhawb nqa los ntawm qee lub mloog pob ntseg, tab sis tsis muaj kev txhawb nqa ntawm cov txheej txheem ua haujlwm niaj hnub no. Nws zoo nkaus li tias pawg neeg thib peb BlueSoleil rau Windows tuaj yeem nkag mus rau MP3 yog tias koj hloov pauv cov ntaub ntawv teeb tsa, tab sis rau kuv kev txhim kho nws ua rau BSoD ntawm Windows 10. Cov lus xaus - lub codec yeej tsis tuaj yeem siv rau Bluetooth suab.
Yav dhau los, xyoo 2006-2008, ua ntej kev sib kis ntawm A2DP tus qauv hauv cov khoom siv, tib neeg tau mloog MP3 suab paj nruag ntawm Nokia BH-501 headset los ntawm MSI BluePlayer program, uas muaj nyob rau ntawm Symbian thiab Windows Mobile. Lub sijhawm ntawd, OS architecture ntawm smartphones tau tso cai nkag mus rau ntau lub luag haujlwm qis, thiab ntawm Windows Mobile nws tseem muaj peev xwm los nruab qhov thib peb tog Bluetooth pawg.

Qhov kawg patent ntawm MP3 codec tau tas sij hawm, kev siv lub codec tsis tas yuav tsum tau daim ntawv tso cai nqi txij li lub Plaub Hlis 23, 2017.

Yog tias qhov ntev tshaj plaws patent tau hais nyob rau hauv cov lus hais saum toj no tau raug coj los ntsuas, ces MP3 thev naus laus zis tau dhau los ua patent-dawb hauv Tebchaws Meskas thaum lub Plaub Hlis 16, 2017 thaum US Patent 6,009,399, tuav los ntawm Technicolor, tas sij hawm.

Tau qhov twg los: www.iis.fraunhofer.de/en/ff/amm/prod/audiocodec/audiocodecs/mp3.html

Sampling zaus
Tus nqi
Kev them nyiaj yug encoding
Kev them nyiaj yug decoding

16-48 kHz
8 - 320 kbps
Tsis txhawb qhov twg
Qee cov khoom siv suab (hardware)

LDAC

Ib qho tshiab thiab nquag txhawb nqa "Hi-Res" codec los ntawm Sony, txhawb nqa tus lej mus txog 96 kHz thiab 24-ntsis bitrate, nrog bitrates txog 990 kbps. Nws tau tshaj tawm raws li audiophile codec, hloov pauv rau Bluetooth codecs uas twb muaj lawm. Nws muaj kev ua haujlwm ntawm kev hloov kho bitrate, nyob ntawm cov xov tooj cua tshaj tawm.

LDAC encoder (libldac) yog suav nrog hauv cov qauv hauv pob, yog li kev encoding tau txais kev txhawb nqa ntawm txhua lub xov tooj hauv Android pib nrog OS version 8. Tsis muaj cov software decoders pub dawb, cov codec specification tsis muaj rau cov pej xeem, txawm li cas los xij, thaum xub thawj siab ib muag ntawm tus encoder, cov qauv sab hauv ntawm codec zoo ib yam li. ATRAC 9 - Sony tus codec siv nyob rau hauv PlayStation 4 thiab Vita: ob qho tib si ua haujlwm nyob rau hauv ntau zaus, siv qhov hloov pauv hloov pauv cosine (MDCT) thiab compression siv Huffman algorithm.

LDAC kev txhawb nqa yog muab yuav luag tshwj xeeb los ntawm lub mloog pob ntseg los ntawm Sony. Lub peev xwm los txiav txim siab LDAC qee zaum pom ntawm lub mloog pob ntseg thiab DACs los ntawm lwm cov tuam txhab, tab sis tsis tshua muaj.

Sampling zaus
Tus nqi
Kev them nyiaj yug encoding
Kev them nyiaj yug decoding

44.1-96 kHz
303/606/909 kbit/s (rau 44.1 thiab 88.2 kHz), 330/660/990 kbit/s (rau 48 thiab 96 kHz)
Hauv 8 +
Qee cov Sony lub mloog pob ntseg thiab qee cov khoom siv los ntawm lwm cov tuam ntxhab (hardware)

Kev lag luam LDAC raws li Hi-Res codec ua phem rau nws cov khoom siv: nws yog ruam los siv bitrate ntawm kev xa cov zaus tsis hnov ​​​​tsw rau tib neeg lub pob ntseg thiab nce qhov tob me ntsis, thaum nws tsis txaus los xa CD-zoo (44.1/16) yam tsis poob. . Hmoov zoo, tus codec muaj ob hom kev khiav hauj lwm: CD suab kis tau tus mob thiab Hi-Res suab kis. Hauv thawj kis, tsuas yog 44.1 kHz / 16 khoom kis tau los ntawm huab cua.

Txij li thaum lub software LDAC decoder tsis muaj kev ywj pheej, nws tsis tuaj yeem kuaj cov codec yam tsis muaj cov khoom siv ntxiv uas txiav txim siab LDAC. Raws li cov txiaj ntsig ntawm LDAC xeem ntawm DAC nrog nws cov kev txhawb nqa, uas SoundGuys.com engineers txuas nrog los ntawm cov zis digital thiab kaw cov suab tso tawm ntawm cov teeb liab ntsuas, LDAC 660 thiab 990 kbps hauv CD-zoo hom muab lub teeb liab-rau- suab nrov piv me ntsis zoo dua li ntawm aptX HD.

Tau qhov twg los: www.soundguys.com/ldac-ultimate-bluetooth-guide-20026

LDAC kuj tseem txhawb nqa dynamic bitrates sab nraum cov tsim profiles - los ntawm 138 kbps mus rau 990 kbps, tab sis raws li kuv tau qhia, Android tsuas yog siv tus qauv profiles 303/606/909 thiab 330/660/990 kbps.

Lwm yam codecs

Lwm yam A2DP codecs tsis tau siv dav. Lawv qhov kev txhawb nqa yog yuav luag tsis muaj tag nrho lossis tsuas yog muaj nyob ntawm qee cov qauv ntawm lub mloog pob ntseg thiab smartphones.
ATRAC codec tus qauv hauv A2DP yeej tsis tau siv los ua Bluetooth codec txawm tias los ntawm Sony lawv tus kheej, Samsung HD, Samsung Scalable thiab Samsung UHQ-BT codecs muaj kev txhawb nqa tsawg heev los ntawm kev xa tawm thiab tau txais cov cuab yeej, thiab HWA LHDC yog qhov tshiab thiab tsuas yog txhawb nqa peb. (?) cov khoom siv.

Kev them nyiaj yug codec rau cov khoom siv suab

Tsis yog txhua tus neeg tsim khoom lag luam tshaj tawm cov ntaub ntawv tseeb txog cov codecs uas tau txais kev txhawb nqa los ntawm qee lub wireless headphones, hais lus, receivers lossis transmitters. Qee lub sij hawm nws tshwm sim tias kev txhawb nqa rau qee qhov codec tsuas yog rau kev sib kis xwb, tab sis tsis yog rau kev txais tos (tseem ceeb rau kev sib koom ua ke transmitters-receivers), txawm hais tias cov chaw tsim khoom tsuas tshaj tawm "kev txhawb nqa", yam tsis muaj ntawv sau tseg (Kuv xav tias cais cov ntawv tso cai ntawm encoders thiab decoders ntawm qee qhov. codecs yog los liam rau qhov no). Hauv cov khoom siv pheej yig tshaj plaws, koj yuav tsis pom qhov tshaj tawm aptX txhawb nqa txhua.

Hmoov tsis zoo, lub interfaces ntawm feem ntau cov kev khiav hauj lwm systems tsis tso saib cov codec siv nyob qhov twg. Cov ntaub ntawv hais txog qhov no tsuas yog muaj nyob hauv Android, pib ntawm version 8, thiab macOS. Txawm li cas los xij, txawm tias nyob rau hauv cov OSs no, tsuas yog cov codecs uas tau txais kev txhawb nqa los ntawm ob lub xov tooj / khoos phis tawj thiab lub mloog pob ntseg yuav tshwm sim.

Koj tuaj yeem nrhiav tau cov codecs koj lub cuab yeej txhawb nqa li cas? Sau thiab txheeb xyuas cov tsheb thauj mus los nrog A2DP kev sib tham tsis tau!
Qhov no tuaj yeem ua tiav ntawm Linux, macOS thiab Android. Ntawm Linux koj tuaj yeem siv Wireshark lossis hcidump, ntawm macOS koj tuaj yeem siv Bluetooth Explorer, thiab hauv Android koj tuaj yeem siv tus qauv Bluetooth HCI pob tseg txoj haujlwm, uas muaj nyob hauv cov cuab yeej tsim tawm. Koj yuav tau txais cov pob tseg hauv btsnoop hom, uas tuaj yeem thauj mus rau hauv Wireshark analyzer.
Tshem nyiaj: Cov pob tseg kom raug tsuas yog tau los ntawm kev sib txuas ntawm koj lub xov tooj / khoos phis tawj mus rau lub mloog pob ntseg / hais lus (txawm hais tias nws yuav zoo li cas)! Lub mloog pob ntseg tuaj yeem tsim kev sib txuas nrog lub xov tooj ntawm nws tus kheej, nyob rau hauv rooj plaub twg lawv yuav thov cov npe codecs los ntawm lub xov tooj, thiab tsis ua rau lwm tus. Txhawm rau kom ntseeg tau tias qhov pov tseg raug kaw, ua ntej unpair lub cuab yeej thiab tom qab ntawd khi koj lub xov tooj nrog lub mloog pob ntseg thaum kaw lub pob tseg.

Siv cov ntxaij lim dej hauv qab no los lim tawm cov tsheb tsis sib xws:

btavdtp.signal_id

Yog li ntawd, koj yuav tsum pom qee yam zoo ib yam li qhov no:

Koj tuaj yeem nyem rau ntawm txhua yam khoom hauv GetCapabilities hais kom saib cov ncauj lus kom ntxaws ntawm codec.

Wireshark tsis paub txhua tus cim codec, yog li qee tus codecs yuav tsum tau decrypted manually, saib ntawm cov lus qhia hauv qab no:

Mandatory:
0x00 - SBC

Optional:
0x01 - MPEG-1,2 (aka MP3)
0x02 - MPEG-2,4 (aka AAC)
0x04 - ATRAC

Vendor specific:
0xFF 0x004F 0x01   - aptX
0xFF 0x00D7 0x24   - aptX HD
0xFF 0x000A 0x02   - aptX Low Latency
0xFF 0x00D7 0x02   - aptX Low Latency
0xFF 0x000A 0x01   - FastStream
0xFF 0x012D 0xAA   - LDAC
0xFF 0x0075 0x0102 - Samsung HD
0xFF 0x0075 0x0103 - Samsung Scalable Codec
0xFF 0x053A 0x484C - Savitech LHDC

0xFF 0x000A 0x0104 - The CSR True Wireless Stereo v3 Codec ID for AAC
0xFF 0x000A 0x0105 - The CSR True Wireless Stereo v3 Codec ID for MP3
0xFF 0x000A 0x0106 - The CSR True Wireless Stereo v3 Codec ID for aptX

Nyob rau hauv thiaj li tsis mus soj ntsuam dumps manually, kuv ua ib tug kev pab cuam uas yuav soj ntsuam txhua yam txiav: btcodecs.valdikss.org.ru

Kev sib piv ntawm codecs. Qhov codec twg zoo dua?

Txhua codec muaj nws tus kheej zoo thiab qhov tsis zoo.
aptX thiab aptX HD siv cov ntaub ntawv nyuaj uas tsis tuaj yeem hloov pauv yam tsis tau hloov kho lub encoder thiab decoder. Tsis yog lub tuam txhab xov tooj lossis lub chaw tsim khoom lub mloog pob ntseg tuaj yeem hloov pauv qhov bitrate lossis aptX encoding yam. Tus tswv ntawm lub codec, Qualcomm, muab ib tug siv encoder nyob rau hauv daim ntawv ntawm lub tsev qiv ntawv. Cov lus tseeb no yog lub zog ntawm aptX - koj paub ua ntej qhov zoo ntawm lub suab koj yuav tau txais, tsis muaj "tab sis".

SBC, nyob rau hauv sib piv, muaj ntau configurable tsis, dynamic bitrate (tus encoder yuav txo tau tus bitpool parameter yog hais tias lub airwaves tsis khoom), thiab tsis muaj hard-coded profiles, tsuas yog cov lus pom zoo "zoo nruab nrab" thiab "zoo" uas yog. ntxiv rau A2DP specification hauv 2003 xyoo. "High quality" tsis yog siab dhau los ntawm cov qauv niaj hnub no, thiab feem ntau ntawm Bluetooth pawg tsis tso cai rau koj siv cov kev txwv zoo dua li "zoo" profile, txawm hais tias tsis muaj kev txwv rau qhov no.
Bluetooth SIG tsis muaj kev siv SBC encoder ua lub tsev qiv ntawv, thiab cov chaw tsim khoom siv nws tus kheej.
Cov no yog qhov tsis muaj zog ntawm SBC - nws yeej tsis paub meej ua ntej lub suab zoo li cas los ntawm ib qho khoom siv tshwj xeeb. SBC tuaj yeem tsim tau ob qho tib si suab qis thiab zoo heev, tab sis tom kawg yog qhov tsis tuaj yeem ua tsis tau yam tsis muaj kev cuam tshuam lossis hla cov kev txwv tsis pub siv ntawm Bluetooth pawg.

Qhov xwm txheej nrog AAC yog qhov tsis meej: ntawm ib sab, theoretically tus codec yuav tsum tsim qhov zoo sib txawv ntawm qhov qub, tab sis nyob rau hauv kev xyaum, txiav txim los ntawm cov kev ntsuam xyuas ntawm SoundGuys lub chaw soj nstuam ntawm ntau yam hauv Android, qhov no tsis tau lees paub. Feem ntau yuav, qhov txhaum yog nrog cov khoom siv tsis zoo ntawm lub suab encoders ua rau ntau lub xov tooj chipsets. Nws ua rau kev txiav txim siab siv AAC nkaus xwb ntawm Apple li, thiab hauv Android kom txwv nws rau aptX thiab LDAC.

Cov khoom siv uas txhawb nqa lwm cov codecs feem ntau ua tau zoo dua, tsuas yog vim tias pheej yig heev, cov khoom siv tsis zoo, nws tsis tsim nyog them cov nqi ntawv tso cai siv cov codecs. Hauv kuv qhov kev xeem, SBC suab zoo heev ntawm cov cuab yeej zoo.

Kuv tau ua ib qho kev pabcuam web uas encodes suab rau SBC, aptX thiab aptX HD nyob rau lub sijhawm, txoj cai hauv browser. Nrog nws, koj tuaj yeem sim cov suab codecs yam tsis tau xa suab ntawm Bluetooth, ntawm txhua lub mloog pob ntseg, hais lus, thiab koj cov suab paj nruag uas koj nyiam, thiab tseem hloov pauv tsis tau ncaj qha thaum ua si suab:
btcodecs.valdikss.org.ru/sbc-encoder
Cov kev pabcuam siv SBC coding cov tsev qiv ntawv los ntawm BlueZ project thiab libopenaptx los ntawm ffmpeg, uas tau muab tso ua ke rau hauv WebAssembly thiab JavaScript los ntawm C, ntawm emscripten, khiav hauv browser. Leej twg yuav npau suav txog yav tom ntej!

Nov yog qhov nws zoo li:

Daim ntawv ceeb toom yuav ua li cas lub suab nrov hloov tom qab 20 kHz rau txawv codecs. Thawj cov ntaub ntawv MP3 tsis muaj zaus tshaj 20 kHz.

Sim hloov cov codecs thiab saib seb koj puas hnov ​​qhov txawv ntawm qhov qub, SBC 53 Joint Stereo (tus qauv thiab feem ntau profile), thiab aptX/aptX HD.

Kuv tuaj yeem hnov ​​qhov txawv ntawm codecs hauv pob ntseg mloog!

Cov neeg uas tsis hnov ​​​​qhov txawv ntawm codecs thaum lub sij hawm sim ntawm lub vev xaib kev pabcuam thov tias lawv hnov ​​​​nws thaum mloog cov nkauj ntawm lub mloog pob ntseg wireless. Alas, qhov no tsis yog lus tso dag lossis cov nyhuv placebo: qhov sib txawv yog mloog tiag tiag, tab sis nws tsis yog tshwm sim los ntawm qhov sib txawv codecs.

Feem ntau ntawm Bluetooth audio chipsets siv nyob rau hauv wireless txais cov cuab yeej yog nruab nrog Digital Signal Processor (DSP), uas siv cov sib npaug, compander, stereo expander, thiab lwm yam tsim los txhim kho (lossis hloov) lub suab. Cov neeg tsim khoom siv Bluetooth tuaj yeem teeb tsa DSP rau txhua tus codec cais, thiab thaum hloov pauv ntawm cov codecs, cov neeg mloog yuav xav tias lawv hnov ​​​​qhov txawv ntawm kev ua haujlwm ntawm cov codecs, thaum qhov tseeb lawv tau mloog ntau qhov sib txawv ntawm DSP.

DSP Kalimba audio processing pipeline hauv chips tsim los ntawm CSR/Qualcomm

Ua kom cov DSP sib txawv rau txhua tus codec thiab cov zis sib cais

Qee cov khoom siv hwm zoo tuaj nrog software uas tso cai rau koj los hloov kho DSP chaw, tab sis feem ntau pheej yig dua lub mloog pob ntseg tsis ua, thiab cov neeg siv tsis tuaj yeem kaw suab tom qab ua tiav manually.

Functional nta ntawm cov khoom siv

Cov niaj hnub version ntawm A2DP tus qauv muaj "Volume Control" muaj nuj nqi - ntaus ntawv ntim tswj siv cov lus txib tshwj xeeb ntawm AVRCP raws tu qauv, uas tswj qhov nce ntawm cov zis theem, es tsis txhob programmatically txo qhov ntim ntawm lub suab. Yog tias thaum koj hloov lub ntim ntawm koj lub mloog pob ntseg, qhov kev hloov pauv tsis sync nrog lub ntim ntawm koj lub xov tooj, ces koj lub mloog pob ntseg lossis lub xov tooj tsis txhawb nqa qhov no. Nyob rau hauv rooj plaub no, nws ua rau kev nkag siab zoo ib txwm mloog cov suab paj nruag nrog lub ntim siab tshaj plaws ntawm lub xov tooj, kho qhov ntim tiag tiag nrog lub mloog pob ntseg - qhov no, lub teeb liab-rau-suab nrov piv yuav zoo dua thiab lub suab zoo. yuav tsum siab dua.
Qhov tseeb, muaj xwm txheej tu siab. Ntawm kuv RealForce OverDrive D1 lub mloog pob ntseg rau SBC, lub kaw lus muaj zog tau qhib, thiab ua kom lub ntim ua rau muaj kev nce qib ntawm cov suab nrov, thaum lub suab nrov tsis hloov (lub teeb liab yog compressed). Vim li no, koj yuav tsum tau teem lub ntim ntawm lub computer mus txog ib nrab, nyob rau hauv cov ntaub ntawv no yog xyaum tsis muaj compression nyhuv.
Raws li kuv cov kev soj ntsuam, txhua lub mloog pob ntseg nrog cov codecs ntxiv txhawb nqa lub ntim ntim tswj kev ua haujlwm, pom tau tias qhov no yog ib qho ntawm cov kev cai rau codec ntawv pov thawj.

Qee lub mloog pob ntseg txhawb nqa txuas ob yam khoom siv tib lub sijhawm. Qhov no tso cai rau koj, piv txwv li, mloog suab paj nruag los ntawm koj lub computer thiab tau txais kev hu los ntawm koj lub xov tooj. Txawm li cas los xij, koj yuav tsum paub tias nyob rau hauv hom no lwm codecs yog neeg xiam thiab tsuas yog siv SBC.

AVDTP 1.3 Ncua Kev Tshaj Tawm muaj nuj nqi tso cai rau lub mloog pob ntseg sib txuas lus ncua sij hawm mus rau lub transmitting ntaus ntawv uas lub suab yeej ua si. Qhov no tso cai rau koj los kho cov synchronization ntawm lub suab nrog video thaum saib cov ntaub ntawv video: yog tias muaj teeb meem nrog lub xov tooj cua kis tau tus mob, lub suab yuav tsis lag tom qab cov yees duab, tab sis ntawm qhov tsis sib xws, cov yees duab yuav qeeb los ntawm cov video player kom txog thaum lub suab thiab yees duab synchronized dua.
Cov haujlwm tau txais kev txhawb nqa los ntawm ntau lub mloog pob ntseg, Android 9+ thiab Linux nrog PulseAudio 12.0+. Kuv tsis paub txog kev txhawb nqa rau qhov no ntawm lwm lub platform.

Kev sib txuas lus bidirectional ntawm Bluetooth. Lub suab kis tau tus mob.

Rau lub suab kis tau tus mob hauv Bluetooth, Synchronous Connection Oriented (SCO) yog siv - synchronous kis tau tus mob nrog kev sib tham ua ntej ntawm kev sib txuas. Cov hom tso cai rau koj kom xa cov suab thiab lub suab nruj me ntsis raws li kev txiav txim, nrog kev xa thiab tau txais nrawm, tsis tas tos kom pom tseeb ntawm kev sib kis thiab rov xa cov pob ntawv. Qhov no txo ​​qhov kev ncua sij hawm tag nrho ntawm lub suab xa mus rau hauv xov tooj cua channel, tab sis ua rau muaj kev txwv loj ntawm cov ntaub ntawv xa mus rau ib chav tsev ntawm lub sijhawm, thiab cuam tshuam rau qhov zoo.
Thaum siv hom no, ob lub suab thiab lub suab kis tau zoo tib yam.
Hmoov tsis zoo, txij li xyoo 2019, lub suab zoo tshaj Bluetooth tseem tsis zoo, thiab nws tsis paub meej vim li cas Bluetooth SIG tsis ua dab tsi txog nws.

CVSD

CVSD lub suab codec yog tus qauv hauv xyoo 2002, thiab tau txais kev txhawb nqa los ntawm txhua yam khoom siv sib txuas lus Bluetooth. Nws muab cov suab sib kis nrog cov qauv piv txwv ntawm 8 kHz, uas sib haum rau qhov zoo ntawm cov xov tooj sib txuas lus zoo.

Ib qho piv txwv ntawm kev kaw hauv qhov codec no.

mSBC

Qhov ntxiv mSBC codec tau tsim nyob rau hauv 2009, thiab nyob rau hauv 2010 chips siv nws rau lub suab kis tau tus mob twb tshwm sim. mSBC tau dav txhawb los ntawm ntau yam khoom siv.
Qhov no tsis yog ib qho kev ywj pheej codec, tab sis ib txwm SBC los ntawm A2DP tus qauv, nrog rau qhov profile ruaj khov: 16 kHz, mono, bitpool 26.

Ib qho piv txwv ntawm kev kaw hauv qhov codec no.

Tsis ci ntsa iab, tab sis zoo dua li CVSD, tab sis nws tseem cuam tshuam rau kev siv kev sib txuas lus hauv online, tshwj xeeb tshaj yog thaum koj siv lub mloog pob ntseg los sib txuas lus hauv-kev ua si - qhov kev ua si lub suab kuj yuav raug xa mus rau tus nqi piv txwv ntawm 16 kHz.

FastStreamCSR lub tuam txhab txiav txim siab los tsim lub tswv yim ntawm kev siv SBC. Txhawm rau kom tau txais ib puag ncig cov kev txwv ntawm SCO raws tu qauv thiab siv cov bitrates siab dua, CSR tau mus rau lwm txoj hauv kev - lawv tau qhia txog kev txhawb nqa rau ob-txoj kev SBC suab rau hauv A2DP ib-txoj kev suab kis tus qauv, tus qauv encoding profiles, thiab hu nws "FastStream".

FastStream xa cov suab tso suab ntawm 44.1 lossis 48 kHz nrog lub bitrate ntawm 212 kbps rau cov neeg hais lus, thiab mono, 16 kHz, nrog ib tug bitrate ntawm 72 kbps yog siv los xa suab los ntawm lub microphone (me ntsis zoo dua mSBC). Xws li qhov tsis zoo yog qhov zoo dua rau kev sib txuas lus hauv kev ua si hauv online - lub suab ntawm kev ua si thiab cov interlocutors yuav ua tau zoo.

Ib qho piv txwv ntawm kev kaw hauv qhov codec no (+ suab los ntawm microphone, tib yam li mSBC).

Lub tuam txhab tuaj nrog ib qho kev nthuav crutch, tab sis vim qhov tseeb tias nws cuam tshuam tus qauv A2DP, nws tau txais kev txhawb nqa tsuas yog hauv qee lub tuam txhab cov khoom xa tawm (uas ua haujlwm raws li USB audio card, tsis yog Bluetooth ntaus ntawv), tab sis nws tsis yog. tau txais kev txhawb nqa hauv Bluetooth stacks. Txawm hais tias tus naj npawb ntawm lub mloog pob ntseg nrog FastStream kev txhawb nqa tsis yog tsawg.

Tam sim no, FastStream txhawb nqa hauv OS nkaus xwb ua ib thaj rau Linux PulseAudio los ntawm tus tsim tawm Pali Rohár, uas tsis suav nrog hauv ceg tseem ceeb ntawm txoj haujlwm.

aptX Tsis Muaj Tsawg

Ntau yam rau koj xav tsis thoob, aptX Low Latency kuj txhawb nqa ob txoj kev suab, siv tib txoj cai raws li FastStream.
Nws tsis tuaj yeem siv qhov no ntawm tus codec nyob qhov twg - tsis muaj kev txhawb nqa rau Low Latency decoding nyob rau hauv ib qho OS lossis hauv ib pawg Bluetooth paub rau kuv.

Bluetooth 5, Classic thiab Tsawg Zog

Muaj ntau qhov tsis meej pem nyob ib ncig ntawm Bluetooth specifications thiab versions vim muaj ob tus qauv incompatible nyob rau hauv tib lub hom, ob qho tib si yog dav siv rau ntau lub hom phiaj.

Muaj ob qhov sib txawv, tsis sib xws Bluetooth raws tu qauv: Bluetooth Classic thiab Bluetooth Tsawg Zog (LE, tseem hu ua Bluetooth Smart). Kuj tseem muaj cov txheej txheem thib peb, Bluetooth Kev Kub Ceev, tab sis nws tsis yog dav thiab tsis siv hauv cov khoom siv hauv tsev.

Pib nrog Bluetooth 4.0, kev hloov pauv hauv cov lus qhia tshwj xeeb yog Bluetooth Tsawg Zog, thiab Classic version tau txais kev txhim kho me me xwb.

Daim ntawv teev cov kev hloov pauv ntawm Bluetooth 4.2 thiab Bluetooth 5:

9 Hloov los ntawm v4.2 rau 5.0

9.1 TSHIAB NTA

Ob peb yam tshiab tau qhia hauv Bluetooth Core Specification 5.0 Tawm. Cov cheeb tsam loj ntawm kev txhim kho yog:
• Slot Availability Mask (SAM)
• 2 Msym/s PHY for LE
•LE Long Range
• Lub Hwjchim Loj Loj Tsis Txuas Kev Tshaj Tawm
• LE Advertising Extensions
• LE Channel Xaiv Algorithm #2
9.1.1 Nta Ntxiv hauv CSA5 - Kev sib xyaw ua ke hauv v5.0
• Siab tso zis ntau zog

Tau qhov twg los: www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=421043 (nqe 291)

Tsuas yog ib qho kev hloov pauv cuam tshuam rau Classic version nyob rau hauv lub moj khaum ntawm Bluetooth 5 specification: lawv ntxiv kev txhawb nqa rau Slot Availability Mask (SAM) technology, tsim los txhim kho xov tooj cua sib cais. Tag nrho lwm yam kev hloov pauv cuam tshuam rau Bluetooth LE nkaus xwb (thiab Lub Hwj Chim Siab Tshaj Tawm ib yam nkaus).

Tag nrho Cov khoom siv suab siv tsuas yog Bluetooth Classic. Nws tsis yooj yim sua kom txuas lub mloog pob ntseg thiab hais lus ntawm Bluetooth Tsawg Zog: tsis muaj tus qauv rau kev xa suab siv LE. Tus qauv A2DP, siv rau kev xa cov suab zoo, tsuas yog ua haujlwm los ntawm Bluetooth Classic, thiab tsis muaj qhov sib piv hauv LE.

Xaus - kev yuav cov khoom siv suab nrog Bluetooth 5 tsuas yog vim qhov tshiab ntawm cov txheej txheem yog qhov tsis muaj txiaj ntsig. Bluetooth 4.0 / 4.1 / 4.2 nyob rau hauv cov ntsiab lus ntawm lub suab kis tau tus mob yuav ua hauj lwm raws nraim tib yam.
Yog tias cov lus tshaj tawm ntawm lub mloog pob ntseg tshiab hais txog kev ua haujlwm ntau dua ob npaug thiab txo lub zog siv ua tsaug rau Bluetooth 5, ces koj yuav tsum paub tias lawv tsis nkag siab nws tus kheej lossis ua rau koj yuam kev. Tsis muaj qhov xav tsis thoob, vim tias txawm tias cov tuam txhab ntawm Bluetooth chips hauv lawv cov ntawv tshaj tawm tsis meej pem txog qhov sib txawv ntawm cov qauv tshiab ntawm tus qauv, thiab qee qhov Bluetooth 5 chips txhawb nqa qib thib tsib rau LE, thiab siv 4.2 rau Classic.

Suab kis tau tus mob qeeb

Tus nqi qeeb (lag) hauv suab yog nyob ntawm ntau yam: qhov loj ntawm qhov tsis nyob hauv lub suab pawg, hauv Bluetooth pawg thiab hauv lub wireless playback ntaus ntawv nws tus kheej, thiab algorithmic ncua ntawm lub codec.

Lub latency ntawm cov codecs yooj yim xws li SBC, aptX thiab aptX HD yog qhov me me, 3-6 ms, uas tuaj yeem tsis quav ntsej, tab sis nyuaj codecs zoo li AAC thiab LDAC tuaj yeem ua rau pom kev lag luam. AAC algorithmic latency rau 44.1 kHz yog 60 ms. LDAC - txog 30 ms (raws li kev soj ntsuam ntxhib ntawm qhov chaws. Kuv tuaj yeem yuam kev, tab sis tsis ntau.)

Qhov tshwm sim latency zoo heev nyob ntawm lub ntaus ntawv playback, nws cov chipset thiab tsis. Thaum kuaj, kuv tau txais kev sib kis ntawm 150 txog 250 ms ntawm cov khoom siv sib txawv (nrog SBC codec). Yog tias peb xav tias cov khoom siv txhawb nqa ntxiv codecs aptX, AAC thiab LDAC siv cov khoom zoo thiab qhov loj me me, peb tau txais cov latencies hauv qab no:

SBC: 150-250ms
aptX: 130-180 ms
AAC: 190-240 ms
LDAC: 160-210 ms

Cia kuv ceeb toom rau koj: aptX Low Latency tsis tau txais kev txhawb nqa hauv kev ua haujlwm, uas yog vim li cas qis latency tsuas tuaj yeem tau txais nrog lub transmitter + receiver lossis transmitter + headphones / speaker ua ke, thiab tag nrho cov khoom siv yuav tsum txhawb cov codec no.

Bluetooth ntaus ntawv, ntawv pov thawj, thiab logo teeb meem

Yuav ua li cas paub qhov txawv ntawm lub suab zoo los ntawm cov khoom siv pheej yig? Nyob rau hauv tsos, ua ntej ntawm tag nrho cov!

Rau pheej yig Suav headphones, hais lus thiab receivers:

1. Lo lus "Bluetooth" yog ploj lawm ntawm lub thawv thiab khoom siv, "Wireless" thiab "BT" feem ntau siv.
2. Bluetooth logo ploj lawm ntawm lub thawv lossis khoom siv
3. Tsis muaj xiav flashing LED

Qhov tsis muaj cov ntsiab lus no qhia tau hais tias cov cuab yeej tsis tau lees paub, uas txhais tau tias nws muaj peev xwm ua tau zoo thiab muaj teeb meem. Piv txwv li, Bluedio headphones tsis tau lees paub Bluetooth thiab tsis ua raws li A2DP specification. Lawv yuav tsis dhau daim ntawv pov thawj.

Cia peb xav txog ntau yam khoom siv thiab lub thawv los ntawm lawv:

Cov no yog tag nrho cov khoom siv tsis tau lees paub. Cov lus qhia yuav muaj lub logo thiab lub npe ntawm Bluetooth technology, tab sis qhov tseem ceeb tshaj plaws yog tias lawv nyob ntawm lub thawv thiab / lossis lub cuab yeej nws tus kheej.

Yog tias koj lub mloog pob ntseg lossis tus neeg hais lus hais tias "Ze bluetooth dewise txuas nrog zoo", qhov no kuj tsis qhia lawv qhov zoo:

xaus

Bluetooth puas tuaj yeem hloov lub mloog pob ntseg thiab lub mloog pob ntseg? Nws muaj peev xwm, tab sis ntawm tus nqi ntawm kev hu tsis zoo, nce suab latency uas tuaj yeem ua rau muaj kev ntxhov siab hauv kev ua si, thiab tus tswv tsev ntawm cov codecs uas yuav tsum tau them tus nqi ntawv tso cai thiab nce tus nqi kawg ntawm ob lub xov tooj smartphones thiab lub mloog pob ntseg.

Kev lag luam ntawm lwm cov codecs yog qhov muaj zog heev: aptX thiab LDAC tau nthuav tawm raws li kev hloov pauv ntev ntev rau SBC "tam sim no thiab phem", uas tsis yog ze li qhov phem li tib neeg xav tias nws yog.

Raws li nws tau muab tawm, cov kev txwv dag ntawm Bluetooth pawg ntawm SBC bitrate tuaj yeem hla dhau, yog li SBC yuav tsis qis dua rau aptX HD. Kuv tau txais kev pib rau hauv kuv tus kheej tes thiab ua ib thaj rau LineageOS firmware: Peb hloov kho Bluetooth pawg los txhim kho lub suab ntawm lub mloog pob ntseg yam tsis muaj AAC, aptX thiab LDAC codecs

Xav paub ntau ntxiv tuaj yeem pom ntawm cov vev xaib Suab Hmoob и SoundExpert.

Lawm: SBC siv encoder, A2DP bitstream cov ntaub ntawv thiab cov ntaub ntawv xeem. Cov ntaub ntawv no tau siv los tshaj tawm rau pej xeem hauv lub vev xaib Bluetooth, tab sis tam sim no tsuas yog muaj rau cov tswv cuab ntawm Bluetooth SIG.

Tau qhov twg los: www.hab.com