Ngenxa yokuveliswa kobuninzi bee-smartphones ngaphandle kwe-3.5 mm i-jack audio, i-headphones ye-Bluetooth engenazintambo ibe yindlela ephambili yokuba abaninzi baphulaphule umculo kunye nokunxibelelana kwimodi ye-headset.
Abavelisi bezixhobo ezingenazingcingo abasoloko bebhala iinkcukacha ezicacileyo zemveliso, kwaye amanqaku amalunga ne-Bluetooth audio kwi-Intanethi ayaphikisana, ngamanye amaxesha ayilunganga, ayithethi ngazo zonke iimpawu, kwaye ihlala ikopa ulwazi olufanayo olungahambelani nenyani.
Makhe sizame ukuqonda i-protocol, amandla e-Bluetooth OS stacks, i-headphones kunye nezithethi, ii-codecs zeBluetooth zomculo kunye nentetho, fumanisa ukuba yintoni echaphazela umgangatho wesandi esidlulisiweyo kunye ne-latency, funda indlela yokuqokelela kunye nokucacisa ulwazi malunga ne-codecs exhaswayo kunye nezinye izixhobo. izakhono.

TL; DR:

• SBC - codec eqhelekileyo
• Ii-headphones zineequalizer yazo kunye ne-post-processing ye-codec nganye ngokwahlukileyo
• I-aptX ayilunganga njengoko ipapashiwe
• I-LDAC ithengisa ubullshit
• Umgangatho womnxeba usephantsi
• Unokushumeka iikhowudi zomsindo ze-C kwibhrawuza yakho ngokuziqulunqa kwiWebAssembly nge-emscripten, kwaye aziyi kucotha kakhulu.

Umculo ngeBluetooth

Icandelo elisebenzayo leBluetooth lichongwa ziiprofayili - iinkcukacha zemisebenzi ethile. Ukusasazwa komculo weBluetooth usebenzisa iprofayile yokuhanjiswa komsindo ekumgangatho ophezulu we-A2DP. Umgangatho we-A2DP wamkelwa ngo-2003 kwaye awutshintshanga kakhulu ukususela ngoko.
Ngaphakathi kweprofayili, i-1 ikhowudi ye-codec yobunzima obuphantsi be-SBC, eyenzelwe ngokukodwa i-Bluetooth, kunye ne-3 ezongezelelweyo zisemgangathweni. Kukwayenzeka ukuba usebenzise ii-codecs ezingabhalwanga ekuphunyezweni kwakho.

Ukusukela ngoJuni ka-2019 sikhona kwi-comic ye-xkc nge-14 A2DP codecs:

• SBC ← esemgangathweni kwi-A2DP, exhaswa zizo zonke izixhobo
• MPEG-1/2 Layer 1/2/3 ← umgangatho kwi-A2DP: owaziwayo MP3, esetyenziswa kumabonakude wedijithali MP2, kwaye ayaziwa MP1
• MPEG-2/4 AAC ← umgangatho kwi-A2DP
• I-ATRAC ← ikhowudi endala yakwaSony, esemgangathweni kwi-A2DP
• I-LDAC ← ikhowudi entsha evela kwaSony
• i-aptX ← codec ukusuka 1988
• I-aptX HD ← iyafana ne-aptX, kuphela ngeendlela ezahlukeneyo zokukhowudwa
• I-aptX iLatency ephantsi ← ikhowudi eyahlukileyo ngokupheleleyo, akukho kuphunyezwa kwesoftware
• I-aptX eguqukayo ← enye ikhowudi evela kwiQualcomm
• FastStream ← pseudo codec, bidirectional SBC modification
• HWA LHDC ← ikhowudi entsha evela kuHuawei
• Samsung HD ← ixhaswa zizixhobo ezi-2
• Samsung Scalable ← ixhaswa zizixhobo ezi-2
• I-Samsung UHQ-BT ← ixhaswa zizixhobo ezi-3

Kutheni sifuna ii-codecs kuzo zonke, ubuza, xa iBluetooth ine-EDR, ekuvumela ukuba udlulise idatha ngesantya se-2 kunye ne-3 Mbit / s, kunye ne-PCM enganyanzeliswanga ezimbini ze-16-bit, i-1.4 Mbit / s yanele?

Ugqithiso lwedatha ngeBluetooth

Kukho iintlobo ezimbini zokudluliselwa kwedatha kwi-Bluetooth: I-Asynchronous Connection Less (ACL) yokudluliselwa kwe-asynchronous ngaphandle kokusekwa koxhulumaniso, kunye ne-Synhronous Connection Oriented (SCO), ukutshintshwa kwe-synchronous kunye nengxoxo yokuqala yoqhagamshelwano.
Ukuhanjiswa kuqhutyelwa ngokusebenzisa iskimu sokwahlula ixesha kunye nokukhetha umjelo wokuhambisa kwipakethi nganye ngokwahlukileyo (i-Frequency-Hop / Time-Division-Duplex, FH / TDD), apho ixesha lihlulwe kwii-625-microsecond intervals ezibizwa ngokuba yi-slots. Esinye sezixhobo sithumela kwiindawo zokubeka amanani alinganayo, esinye kwiindawo zokubeka ezinamanani angaqhelekanga. Ipakethe ethunyelwayo inokuthatha i-1, i-3 okanye i-5 kwiindawo zokubeka, kuxhomekeke kubukhulu bedatha kunye nohlobo olusetiweyo lokudluliselwa, kulo mzekelo, ukuhanjiswa ngesixhobo esinye kuqhutyelwa kwiindawo zokubeka ezilinganayo kunye ezingaqhelekanga kude kube sekupheleni kokudluliselwa. Lilonke, ukuya kuthi ga kwiipakethi ze-1600 zingafunyanwa kwaye zithunyelwe ngesekhondi, ukuba ngamnye kubo uhlala kwi-1 slot, kwaye zombini izixhobo zihambisa kwaye zifumana into ngaphandle kokuyeka.

I-2 kunye ne-3 Mbit / s ye-EDR, enokufumaneka kwizaziso kunye nakwiwebhusayithi yeBluetooth, yizinga eliphezulu lokudluliselwa kwesiteshi sayo yonke idatha iyonke (kubandakanywa neentloko zobugcisa kuzo zonke iiprotocol apho idatha kufuneka ifakwe kuyo), kumacala amabini. ngaxeshanye. Esona santya sogqithiso lwedatha siya kwahluka kakhulu.

Ukudlulisa umculo, indlela ye-asynchronous isetyenzisiweyo, phantse rhoqo isebenzisa iipakethi ezifana ne-2-DH5 kunye ne-3-DH5, ephethe inani eliphezulu ledatha kwimodi ye-EDR ye-2 Mbit / s kunye ne-3 Mbit / s, ngokulandelanayo, kwaye ithatha ixesha le-5. -ukwabelana kwiindawo zokubeka.

Ukubonakaliswa kweSchematic yothumelo usebenzisa i-5 slot ngesixhobo esinye kunye ne-1 slot ngenye (DH5 / DH1):


Ngenxa yomgaqo wexesha lokwahlulwa kwamaza omoya, sinyanzelekile ukuba silinde i-625-microsecond time slot emva kokuhambisa ipakethe ukuba isixhobo sesibini asidluliseli nantoni na kuthi okanye sihambisa ipakethi encinci, kunye nexesha elininzi ukuba isixhobo sesibini sihambisa. kwiipakethi ezinkulu. Ukuba ngaphezu kwesinye isixhobo siqhagamshelwe kwifowuni (umzekelo, ii-headphones, iiwotshi kunye nesongo sokuqina), ngoko ke ixesha lokudlulisela likwabelwana ngazo phakathi kwazo zonke.

Isidingo sokufakela i-audio kwiiprothokholi ezikhethekileyo zezothutho i-L2CAP kunye ne-AVDTP ithatha i-16 bytes ukusuka kwixabiso eliphezulu elinokubakho lomthwalo womsindo ogqithisiweyo.

Uhlobo lwepakethe
Inani leendawo zokubeka
Max. inani leebhayithi kwipakethi
Max. inani le-A2DP zolayisho lwebhayithi
Max. A2DP payload 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

I-1414 kunye ne-1429 kbps ngokuqinisekileyo ayanelanga ukuhambisa iaudio engaxinzelelwanga kwiimeko zangempela, kunye noluhlu olunomsindo lwe-2.4 GHz kunye nesidingo sokuhambisa idatha yenkonzo. I-EDR 3 Mbit / s ifuna amandla okuhambisa kunye nengxolo emoyeni, ngoko ke, nakwimo ye-3-DH5, ukuhanjiswa kwe-PCM ekhululekile akunakwenzeka, kuya kuhlala kukho ukuphazamiseka kwexesha elifutshane, kwaye yonke into iya kusebenza kuphela kumgama we-PCM. isibini seemitha.
Ngokwenza, nokuba i-990 kbit / s i-audio stream (LDAC 990 kbit / s) kunzima ukuyihambisa.

Masibuyele kwii-codecs.

SBC

I-Codec efunekayo kuzo zonke izixhobo ezixhasa umgangatho we-A2DP. Eyona codec igqwesileyo nembi ngaxeshanye.

Isampulu frequency
Ubunzulu besuntswana
I-Bitrate
Inkxaso yokufaka iikhowudi
Inkxaso yokuguqula ikhowudi

16, 32, 44.1, 48 kHz
I-16 bit
10-1500 kbps
Zonke izixhobo
Zonke izixhobo

I-SBC yi-codec elula kwaye ekhawulezayo ekhompyutheni, kunye nemodeli ye-psychoacoustic yamandulo (i-masking kuphela yezandi ezizolileyo isetyenziswayo), kusetyenziswa i-adaptive pulse code modulation (APCM).
Inkcazo ye-A2DP icebisa iiprofayili ezimbini zokusetyenziswa: uMgangatho oPhakathi kunye noMgangatho oPhezulu.


I-codec inezicwangciso ezininzi ezikuvumela ukuba ulawule ukulibaziseka kwe-algorithmic, inani leesampuli kwibhloko, i-algorithm yokusabalalisa kancinane, kodwa phantse kuyo yonke indawo iiparameters ezifanayo ezicetyiswayo kwinkcazo zisetyenziswa: I-Joint Stereo, i-8 frequency bands, iibhloko ezili-16 ngaphakathi. isakhelo esivakalayo, Indlela yokusasaza kancinci kancinci.
I-SBC ixhasa utshintsho oluguquguqukayo lwepharamitha yeBitpool, echaphazela ngokuthe ngqo i-bitrate. Ukuba amaza omoya avaliwe, iipakethi zilahlekile, okanye izixhobo zibekwe kumgama omkhulu, umthombo womsindo unokunciphisa i-Bitpool de unxibelelwano lubuyele kwisiqhelo.

Uninzi lwabavelisi be-headphone babeka ixabiso eliphezulu le-Bitpool kwi-53, ekhawulela i-bitrate kwi-328 kilobits ngomzuzwana xa usebenzisa iprofayili ekhuthazwayo.
Nokuba umenzi we-headphone usete elona xabiso liphezulu leBitpool ngaphezulu kwama-53 (iimodeli ezinjalo zifunyenwe, umzekelo: Beats Solo³, JBL Everest Elite 750NC, Apple AirPods, nazo zifunyenwe kwabanye abamkeli kunye neeyunithi zentloko yemoto), ke uninzi lwe-OS aluyi kuvumela. ukusetyenziswa kweebitrate ezandisiweyo ngenxa yokuseta umda wexabiso langaphakathi kwizitaki zeBluetooth.
Ukongeza, abanye abavelisi babeka elona xabiso liphezulu leBitpool lisezantsi kwezinye izixhobo. Umzekelo, kwiBluedio T yi-39, ye-Samsung Gear IconX yi-37, enika umgangatho ombi wesandi.

Izithintelo ezenziweyo kwicala labaphuhlisi bezitaki zeBluetooth ezinokuthi zivele ngenxa yokungahambelani kwezinye izixhobo ezinamaxabiso amakhulu eBitpool okanye iiprofayili ezingaqhelekanga, nokuba banike ingxelo yenkxaso kubo, kunye novavanyo olungonelanga ngexesha loqinisekiso. Kwakulula ukuba ababhali bee-stacks zeBluetooth bazikhawulele ukuba bavumelane kwiprofayili ecetyiswayo, kunokuba benze i-database yezixhobo ezingalunganga (nangona ngoku benza oku ngenxa yeminye imisebenzi engalunganga).

I-SBC yabela ngokuguquguqukayo amasuntswana obungakanani kwiibhendi zefrikhwensi kwisiseko esisezantsi ukuya phezulu, ezinobunzima obahlukeneyo. Ukuba yonke ibitrate ibisetyenziselwe amaza aphantsi kunye namaza aphakathi, iifrikhwensi eziphezulu ziya “kunqunyulwa” (kuya kubakho ukuthula endaweni yoko).

Umzekelo SBC 328 kbps. Phezulu yi-original, ezantsi yi-SBC, ngamaxesha athile utshintshe phakathi kweengoma. I-audio kwifayile yevidiyo isebenzisa i-codec yoxinzelelo lwe-FLAC engalahlekiyo. Ukusebenzisa i-FLAC kwisikhongozeli se-mp4 akumiswanga ngokusemthethweni, ngoko ke akuqinisekwanga ukuba isikhangeli sakho siya kuyidlala, kodwa kufuneka isebenze kwiinguqulelo zamva nje ze-desktop yeChrome kunye neFirefox. Ukuba awunaso isandi, unokukhuphela ifayile kwaye uyivule kwisidlali sevidiyo esipheleleyo.
ZZ Top-Ebukhali Indoda Enxibe

I-spectrogram ibonisa umzuzu wokutshintsha: I-SBC ngamaxesha athile isika izandi ezizolileyo ngaphezulu kwe-17.5 kHz, kwaye ayibeki naziphi na iibhithi kwaphela kwibhendi engaphezulu kwe-20 kHz. I-spectrogram epheleleyo iyafumaneka ngokucofa (1.7 MB).

Andiva mahluko phakathi kweyokuqala kunye ne-SBC kule ngoma.

Masithathe into entsha kwaye silingise iaudio eya kufunyanwa kusetyenziswa ii-headsets ze-Samsung Gear IconX nge-Bitpool 37 (ngasentla - umqondiso wokuqala, ongezantsi-SBC 239 kbps, i-audio kwi-FLAC).
Ukuzicekisa ngokungenangqondo - Ngqina

Ndiva ukukhenkceza, isiphumo esincinci se-stereo kunye nesandi esingathandekiyo "sokubetha" kwizandi eziphezulu zamazwi.

Nangona i-SBC iyikhowudi yekhowudi ebhetyebhetye kakhulu, inokuqwalasela ukubambezeleka okuphantsi, ibonelela ngomgangatho obalaseleyo womsindo kwi-bitrate ephezulu (452+ kbps) kwaye ilunge kakhulu kubantu abaninzi kumgangatho oPhezulu oPhakamileyo (328 kbps), ngenxa yokuba umgangatho we-A2DP awucacisi iiprofayili ezisisigxina (kodwa unika iingcebiso kuphela), abaphuhlisi be-stack baye babeka izithintelo ezenziweyo kwi-Bitpool, iiparameters zomsindo ogqithisiweyo aziboniswa kwi-interface yomsebenzisi, kwaye abavelisi bee-headphone bakhululekile ukuseta izicwangciso zabo kwaye bangaze bonisa ixabiso leBitpool kwiinkcukacha zobugcisa zemveliso, i-codec yaduma ngomgangatho wayo ophantsi wesandi, nangona oku akuyona ingxaki kwi-codec enjalo.
Iparameter yeBitpool ichaphazela ngqo ibitrate kuphela ngaphakathi kwiprofayile enye. Ixabiso elifanayo le-Bitpool 53 linokunika zombini i-bitrate ye-328 kbps kunye neprofayili yoMgangatho oPhezulu ocetyiswayo, kunye ne-1212 kbps kunye ne-Dual Channel kunye ne-4 bands frequency, yiyo loo nto ababhali be-OS, ukongeza kwizithintelo kwi-Bitpool, babeka umda kwaye I-Bitrate. Njengoko ndiyibona, le meko yavela ngenxa yesiphene kumgangatho we-A2DP: kwakuyimfuneko ukuxoxisana ne-bitrate, kungekhona i-Bitpool.

Itheyibhile yenkxaso yezakhono ze-SBC kwii-OS ezahlukeneyo:

I-OS
Amazinga esampuli axhaswayo
Umlinganiselo max. I-Bitpool
Umlinganiselo max. I-Bitrate
I-Bitrate eqhelekileyo
Uhlengahlengiso oluguqukayo lweBitpool

10 Windows
44.1 кГц
53
512 kbps
328 kbps
✓*

Linux (BlueZ + PulseAudio)
16, 32, 44.1, 48 kHz
64 (kuqhagamshelwano olungenayo), 53 (uqhagamshelwano oluphumayo)
Akukho mda
328 kbps
✓*

i-MacOS High Sierra
44.1 кГц
64, engagqibekanga 53***
Ayaziwa
328 kbps
✗

I-Android 4.4-9
44.1/48 kHz**
53
328 kbps
328 kbps
✗

I-Android 4.1-4.3.1
44.1, 48 kHz**
53
229 kbps
229 kbps
✗

Blackberry OS 10
48 кГц
53
Akukho mda
328 kbps
✗

* I-Bitpool iyancipha kuphela, kodwa ayinyuki ngokuzenzekelayo, ukuba iimeko zokudlulisa ziphucula. Ukubuyisela iBitpool kufuneka uyeke ukudlala, linda imizuzwana embalwa kwaye uqale iaudio kwakhona.
** Ixabiso elingagqibekanga lixhomekeke kwizicwangciso zestack ezixeliweyo xa uqulunqa i-firmware. Kwi-Android 8/8.1 i-frequency kuphela yi-44.1 kHz okanye i-48 kHz, kuxhomekeke kwizicwangciso ngexesha lokuhlanganiswa, kwezinye iinguqulelo ze-44.1 kHz kunye ne-48 kHz zixhaswa ngaxeshanye.
*** Ixabiso leBitpool linokunyuswa kwinkqubo yeBluetooth Explorer.

I-aptX kunye ne-aptX HD

I-aptX yi-codec elula kwaye ekhawulezayo ekhompyutheni, ngaphandle kwe-psychoacoustics, isebenzisa i-adaptive differential pulse code modulation (I-ADPCM). Yavela malunga ne-1988 (umhla wokufaka ilungelo elilodwa lomenzi wechiza yomhla kaFebruwari 1988), phambi kweBluetooth, yayisetyenziswa ikakhulu kwizixhobo zeaudio ezingenazingcingo. Ngoku ephethwe yi-Qualcomm, ifuna ilayisensi kunye ne-royalties. Ukusukela ngo-2014: $6000 ngexesha elinye kunye ≈$1 ngesixhobo ngasinye, kwiibhetshi ukuya kwi-10000 yezixhobo (umthombo, iphe. 16).
I-aptX kunye ne-aptX HD zi-codec ezifanayo, ezineeprofayili zokufaka iikhowudi ezahlukeneyo.

I-codec ineparameter enye kuphela - ukukhetha i-frequency yesampuli. Kukho, nangona kunjalo, ukhetho lwenani / indlela yamajelo, kodwa kuzo zonke izixhobo ezaziwa kum (iziqwenga ezingama-70+) kuphela iStereo esixhaswayo.

Ikhodekhi
Isampulu frequency
Ubunzulu besuntswana
I-Bitrate
Inkxaso yokufaka iikhowudi
Inkxaso yokuguqula ikhowudi

i-aptX
16, 32, 44.1, 48 kHz
I-16 bit
128 / 256 / 352 / 384 kbps (kuxhomekeke kumlinganiselo wesampulu)
Windows 10 (idesktop kunye neselfowuni), macOS, Android 4.4+/7*, Blackberry OS 10
Uluhlu olubanzi lwezixhobo zomsindo (i-hardware)

* Iinguqulelo ukuya kuthi ga kwisi-7 zifuna ukulungiswa kwesitaki seBluetooth. Ikhodekhi ixhaswa kuphela ukuba ngaba umvelisi wesixhobo se-Android unike ilayisenisi yekhowudi esuka kwiQualcomm (ukuba i-OS inamathala eencwadi ekhowudiyo).

I-aptX yohlulahlula isandi kwiibhendi ezi-4 zefrikhwensi kwaye zilinganise ngenani elifanayo leebhithi rhoqo: ii-bits ezi-8 ze-0-5.5 kHz, ii-bits ze-4 ze-5.5-11 kHz, i-2 bits ye-11-16.5 kHz, i-2 bits ye-16.5-22 kHz ( amanani okulinganisa isampuli 44.1 kHz).

Umzekelo we-aptX yomsindo (phezulu - isiginali yoqobo, ezantsi - i-aptX, iispectrogram zamajelo asekhohlo kuphela, isandi kwiFLAC):

Ukuphakama kwaba bomvu kancinci, kodwa wawungeva umahluko.

Ngenxa yosasazo olusisigxina lwe-quantization bits, i-codec ayikwazi "ukutshintsha iibhithi" kwiifrikhwensi ezizifuna kakhulu. Ngokungafaniyo ne-SBC, i-aptX ayiyi "kusika" i-frequencies, kodwa iya kongeza ingxolo ye-quantization kubo, inciphisa uluhlu oluguquguqukayo lwesandi.

Akufanele kucingelwe ukuba ukusebenzisa, umzekelo, iibhithi ezi-2 ngebhanti nganye kunciphisa uluhlu oluguquguqukayo ukuya kwi-12 dB: I-ADPCM ivumela ukuya kwi-96 dB yoluhlu oluguquguqukayo nangona usebenzisa i-2 quantization bits, kodwa kuphela umqondiso othile.
I-ADPCM igcina umahluko wamanani phakathi kwesampulu yangoku kunye nesampulu elandelayo, endaweni yokugcina ixabiso elipheleleyo njengakwi-PCM. Oku kukuvumela ukuba unciphise iimfuno zenani lamasuntswana afunekayo ukugcina okufanayo (ngaphandle kwelahleko) okanye phantse okufanayo (ngempazamo encinci yokurhawulwa) ulwazi. Ukunciphisa iimpazamo zokujikeleza, iitafile ze-coefficient zisetyenziswa.
Xa udala i-codec, ababhali babala i-ADCPM coefficients kwisethi yeefayile zomsindo zomculo. Ukusondela kwesandi somsindo kukuseti yomculo apho iitafile zakhiwe khona, iimpazamo ezincinci ze-quantization (ingxolo) i-aptX iyadala.

Ngenxa yoko, iimvavanyo zokwenziwa ziya kuhlala zivelisa iziphumo ezimbi kunomculo. Ndenze umzekelo okhethekileyo wokwenziwa apho i-aptX ibonisa iziphumo ezibi - i-sine wave ene-frequency ye-12.4 kHz (ngasentla - isibonakaliso sokuqala, ngaphantsi - i-aptX. I-Audio kwi-FLAC. Yehlisa ivolumu!):

Igrafu yeSpectrum:


Ingxolo ivakala ngokucacileyo.

Nangona kunjalo, ukuba uvelisa i-sine wave nge-amplitude encinci ukuze izole, ingxolo iya kuthi cwaka, ibonise uluhlu olubanzi oluguqukayo:

Ukuva umahluko phakathi kwengoma yoqobo kunye necinezelweyo, ungaguqula enye yeempawu kwaye wongeze isitishi seengoma ngetshaneli. Le ndlela, kwimeko jikelele, ayichanekanga kwaye ayinakunika iziphumo eziphilileyo kunye neekhowudi eziyinkimbinkimbi, kodwa ngokukodwa kwi-ADCMM ifanelekile.
Umahluko phakathi koqobo kunye ne-aptX
Ingcambu ithetha umehluko wesikwere weempawu kwinqanaba le--37.4 dB, elingekho kakhulu kumculo onjalo.

I-aptX HD

I-aptX HD ayisiyiyo i-codec ezimeleyo - yiprofayili ephuculweyo yokufakwa kwekhowudi ye-aptX codec. Utshintsho luchaphazele inani lamasuntswana anikezelweyo kwi-encoding frequency ranges: ii-bits eziyi-10 ze-0-5.5 kHz, i-6 bits ye-5.5-11 kHz, i-4 bits ye-11-16.5 kHz, i-4 bits ye-16.5-22 kHz (amanani e-44.1 kHz) .

Ikhodekhi
Isampulu frequency
Ubunzulu besuntswana
I-Bitrate
Inkxaso yokufaka iikhowudi
Inkxaso yokuguqula ikhowudi

I-aptX HD
16, 32, 44.1, 48 kHz
24 bits
192 / 384 / 529 / 576 kbps (kuxhomekeke kumlinganiselo wesampulu)
I-Android 8+*
Ezinye izixhobo zeaudio (hardware)

* Iinguqulelo ukuya kuthi ga kwisi-7 zifuna ukulungiswa kwesitaki seBluetooth. Ikhodekhi ixhaswa kuphela ukuba ngaba umvelisi wesixhobo se-Android unike ilayisenisi yekhowudi esuka kwiQualcomm (ukuba i-OS inamathala eencwadi ekhowudiyo).

Ingaxhaphakanga kune-aptX: ngokucacileyo ifuna ilayisensi eyahlukileyo esuka kwi-Qualcomm, kunye nemirhumo eyahlukeneyo yelayisensi.

Masiphinde umzekelo nge-sine wave kwi-12.4 kHz:


Ingcono kakhulu kune-aptX, kodwa isenengxolo encinci.

I-aptX iLatency ephantsi

I-codec evela kwi-Qualcomm engenanto ehambelanayo kunye ne-aptX eqhelekileyo kunye ne-aptX HD, ukugweba ngolwazi oluncinci oluvela kubantu ababandakanyekayo ekuphuhlisweni kwayo. Yenzelwe ukuhanjiswa kwe-audio ephantsi-latency esebenzayo (iimovie, imidlalo), apho ukulibaziseka komsindo akunakulungelelaniswa yisoftware. Akukho kuphunyezwa kwesoftware eyaziwayo yeekhowudi kunye ne-decoders zixhaswa kuphela ngabathumeli, abamkeli, ii-headphones kunye nezithethi, kodwa hayi ngee-smartphones kunye neekhompyuter.

Isampulu frequency
I-Bitrate
Inkxaso yokufaka iikhowudi
Inkxaso yokuguqula ikhowudi

44.1 кГц
276/420 kbps
Ezinye ii-transmitter (i-hardware)
Ezinye izixhobo zeaudio (hardware)

AAC

I-AAC, okanye i-Advanced Audio Coding, yikhowudi yekhompyutha entsonkothileyo enemodeli enzulu yengqondo. Isetyenziswa kakhulu kwi-audio kwi-Intanethi, okwesibini ekudumeni emva kweMP3. Ifuna ilayisenisi kunye nemivuzo: i-$ 15000 ngexesha elinye (okanye i-$ 1000 kwiinkampani ezinabasebenzi abangaphantsi kwe-15) + $ 0.98 kwizixhobo zokuqala ze-500000 (umthombo).
I-codec isemgangathweni ngaphakathi kwe-MPEG-2 kunye ne-MPEG-4 yenkcazo, kwaye ngokuchasene nembono ephosakeleyo eqhelekileyo, ayiyiyo ye-Apple.

Isampulu frequency
I-Bitrate
Inkxaso yokufaka iikhowudi
Inkxaso yokuguqula ikhowudi

8 - 96 kHz
8 - 576 kbps (ye-stereo), 256 - 320 kbps (eqhelekileyo kwiBluetooth)
macOS, Android 7+*, iOS
Uluhlu olubanzi lwezixhobo zomsindo (i-hardware)

* kuphela kwizixhobo apho abavelisi bawo bahlawule umrhumo welayisenisi

I-iOS kunye ne-macOS zisebenzisa eyona khowudi yangoku ye-AAC ye-Apple ukuhambisa owona mgangatho uphezulu womsindo. I-Android isebenzisa i-encoder yesibini ephezulu yomgangatho weFDK AAC, kodwa inokusebenzisa izixhobo ezahlukeneyo ezakhiwe eqongeni (SoC) ezinomgangatho ongaziwayo wokufakwa kweekhowudi. Ngokweemvavanyo zakutsha nje kwiwebhusayithi yeSoundGuys, umgangatho wokufakwa kwekhowudi ye-AAC yeefowuni ezahlukeneyo ze-Android wahluka kakhulu:

Uninzi lwezixhobo ezimanyelwayo ezingenazingcingo zine-bitrate ephezulu ye-320 kbps ye-AAC, ezinye zixhasa kuphela i-256 kbps. Ezinye iibitrate zinqabile kakhulu.
I-AAC ibonelela ngomgangatho ogqwesileyo kuma-320 kunye nama-256 kbps bitrates, kodwa ixhomekeke ilahleko yolandelelwano lwekhowudi yomxholo osele ucinezelwe, nangona kunjalo, kunzima ukuva nayiphi na iyantlukwano kunye neyokuqala kwi-iOS kwi-bitrate ye-256 kbps kunye neekhowudi ezininzi ezilandelelanayo kunye ne-encoding enye, umzekelo, i-MP3 320 kbps ukuya kwi-AAC 256 kbps, ilahleko inokungahoywa.
Njengakwezinye iicodec zeBluetooth, nawuphi na umculo uqala ukhowudwe uze ukhowudwe yikhowudi. Xa umamele umculo kwifomathi ye-AAC, iqala ukuchithwa yi-OS, emva koko ifakwe kwi-AAC kwakhona ukuze idluliselwe ngeBluetooth. Oku kuyimfuneko ekuxubeni imijelo yomsindo emininzi, njengomculo kunye nezaziso zomyalezo omtsha. I-iOS iyahluka. Kwi-Intanethi unokufumana iingxelo ezininzi kumculo we-iOS kwifomathi ye-AAC ayidluliswanga xa ihanjiswa ngeBluetooth, engeyonyani.

MP1/2/3

Iicodecs zeMPEG-1/2 Part 3 zosapho zibandakanya iMP3 eyaziwayo nesetyenziswa ngokubanzi, iMP2 engaqhelekanga (esetyenziswa kakhulu kumabonakude wedijithali kunye nonomathotholo), kunye neMP1 engaziwayo ngokupheleleyo.

Iikhowudi zamandulo zeMP1 kunye neMP2 azixhaswanga kwaphela: andifumananga naziphi na ii-headsets okanye isitaki seBluetooth esinokuthi sizifakele ikhowudi okanye zisichaze.
Ukwenziwa kwekhowudi yeMP3 kuxhaswa zezinye ii-headphones, kodwa ukufakwa kweekhowudi akuxhaswa nakweyiphi na inkqubo yokusebenza yale mihla. Kubonakala ngathi i-blueSoleil ye-third party stack ye-Windows inokufaka ikhowudi kwi-MP3 ukuba utshintshe ngesandla ifayile yoqwalaselo, kodwa kum ukuyifaka ikhokelela kwi-BSoD Windows 10. Isiphelo - i-codec eneneni ayinakusetyenziswa kwi-audio yeBluetooth.
Ngaphambili, ngo-2006-2008, ngaphambi kokusasazeka komgangatho we-A2DP kwizixhobo, abantu baphulaphule umculo weMP3 kwi-headset ye-Nokia BH-501 ngeprogram ye-MSI BluePlayer, eyayifumaneka kwi-Symbian kunye ne-Windows Mobile. Ngelo xesha, i-architecture ye-OS yee-smartphones yavumela ukufikelela kwimisebenzi emininzi ephantsi, kwaye kwi-Windows Mobile kwakunokwenzeka ukuba ufake i-stacks ye-Bluetooth yomntu wesithathu.

I-patent yokugqibela ye-MP3 codec iphelelwe lixesha, ukusetyenziswa kwe-codec akufuni ntlawulo yelayisensi ukususela ngo-Aprili 23, 2017.

Ukuba elona patent ithatha ixesha elide ikhankanywe kwezi zingqinisiso zikhankanywe ngasentla ithathwa njengomlinganiselo, ngoko ke iteknoloji yeMP3 iye yaphelelwa patent eUnited States ngoAprili 16, 2017 xa i-US Patent 6,009,399, egcinwe kwaye ilawulwa yiTechnicolor, iphelelwe lixesha.

umthombo: www.iis.fraunhofer.de/en/ff/amm/prod/audiocodec/audiocodecs/mp3.html

Isampulu frequency
I-Bitrate
Inkxaso yokufaka iikhowudi
Inkxaso yokuguqula ikhowudi

16 - 48 kHz
8 - 320 kbps
Ayixhaswa naphi na
Ezinye izixhobo zeaudio (hardware)

I-LDAC

Ikhowudi entsha ye-"Hi-Res" ekhuthazwayo evela kwa-Sony, exhasa iisampulu ukuya kuthi ga kwi-96 kHz kunye ne-24-bitrate bitrate, ene-bitrate ukuya kuma-990 kbps. Ipapashwa njenge-audiophile codec, njengendawo ethatha indawo yeekhowudi zeBluetooth ezikhoyo. Inomsebenzi wohlengahlengiso lwe-bitrate elungelelanisiweyo, ngokuxhomekeke kwiimeko zosasazo lukanomathotholo.

Ikhowudi ye-LDAC (libldac) ifakiwe kwiphakheji eqhelekileyo ye-Android, ngoko ke ukufakwa kweekhowudi kuxhaswa kuyo nayiphi na i-smartphone ye-Android eqala nge-OS version 8. Akukho zidekhoda zesoftware ezikhoyo ngokukhululekileyo, ukucaciswa kwekhowudi akufumaneki kuluntu ngokubanzi, nangona kunjalo, ekujongeni okokuqala kwi-encoder, ubume bangaphakathi bekhowudi bufana ne I-ATRAC9 - I-codec ye-Sony esetyenziswe kwi-PlayStation 4 kunye ne-Vita: zombini zisebenza kwi-domain frequency, sebenzisa i-modified discrete cosine transform (MDCT) kunye noxinzelelo usebenzisa i-algorithm ye-Huffman.

Inkxaso ye-LDAC ibonelelwa phantse ngokukodwa ngee-headphones ezivela kwaSony. Ukukwazi ukucacisa i-LDAC ngamanye amaxesha kufumaneka kwii-headphones kunye nee-DAC ezivela kwabanye abavelisi, kodwa kunqabile kakhulu.

Isampulu frequency
I-Bitrate
Inkxaso yokufaka iikhowudi
Inkxaso yokuguqula ikhowudi

44.1 - 96 kHz
303/606/909 kbit/s (ye-44.1 kunye ne-88.2 kHz), 330/660/990 kbit/s (ye-48 kunye ne-96 kHz)
I-Android 8 +
Ezinye ii-headphone ze-Sony kunye nezinye izixhobo ezivela kwabanye abavelisi (i-hardware)

Ukuthengisa i-LDAC njenge-codec ye-Hi-Res yonakalisa icandelo layo lobugcisa: bubudenge ukuchitha i-bitrate kwi-frequencies ehambisa i-frequencies engavakaliyo kwindlebe yomntu kunye nokwandisa ubunzulu be-bit, ngelixa akwanelanga ukuhambisa umgangatho we-CD (44.1 / 16) ngaphandle kwelahleko. . Ngethamsanqa, i-codec ineendlela ezimbini zokusebenza: ukuhanjiswa komsindo we-CD kunye nokuhanjiswa komsindo we-Hi-Res. Kwimeko yokuqala, kuphela i-44.1 kHz/16 bits ihanjiswa emoyeni.

Ekubeni i-software ye-LDAC decoder ayifumaneki ngokukhululekileyo, akunakwenzeka ukuvavanya i-codec ngaphandle kwezixhobo ezongezelelweyo ezicacisa i-LDAC. Ngokweziphumo zovavanyo lwe-LDAC kwi-DAC ngenkxaso yayo, apho iinjineli ze-SoundGuys.com ziqhagamshelwe ngemveliso yedijithali kwaye zirekhoda isandi esiphumayo kwiimpawu zovavanyo, i-LDAC 660 kunye ne-990 kbps kwimowudi ye-CD ibonelela ngomqondiso-kuya-. Umlinganiselo wengxolo ungcono kancinci kune-aptX HD.

umthombo: www.soundguys.com/ldac-ultimate-bluetooth-guide-20026

I-LDAC ikwaxhasa i-bitrate eguqukayo ngaphandle kweenkangeleko ezimisiweyo - ukusuka kwi-138 kbps ukuya ku-990 kbps, kodwa ngokokwazi kwam, i-Android isebenzisa kuphela iiprofayili ezisemgangathweni 303/606/909 kunye ne-330/660/990 kbps.

Ezinye iikhowudi

Ezinye iikhowudi ze-A2DP azisetyenziswa kakhulu. Inkxaso yabo iphantse ingabikho ngokupheleleyo okanye ifumaneka kuphela kwiimodeli ezithile zee-headphones kunye nee-smartphones.
I-codec ye-ATRAC esemgangathweni kwi-A2DP ayizange isetyenziswe njenge-codec yeBluetooth nokuba nguSony ngokwabo, i-Samsung HD, i-Samsung Scalable kunye ne-Samsung UHQ-BT codec zinenkxaso encinci kakhulu yokuhambisa kunye nokufumana izixhobo, kwaye i-HWA LHDC intsha kakhulu kwaye ixhaswa kuphela ezintathu. (?) izixhobo.

Inkxaso yeCodec yezixhobo zomsindo

Akunabo bonke abavelisi abapapasha ulwazi oluchanekileyo malunga nee-codecs ezixhaswa ngee-headphones ezithile ezingenazintambo, izithethi, abamkeli okanye abathumeli. Ngamanye amaxesha kwenzeka ukuba inkxaso ye-codec ethile yeyokusasazwa kuphela, kodwa kungekhona ukwamkelwa (ifanelekile kwii-transmitters-receivers ezidibeneyo), nangona umenzi echaza "inkxaso", ngaphandle kwamanqaku (ndicinga ukuba ilayisensi eyahlukileyo ye-encoders kunye ne-decoders yezinye iicodecs zibekek' ityala ngale nto ). Kwezona zixhobo zinexabiso eliphantsi, usenokungafumani inkxaso ebhengeziweyo ye-aptX kwaphela.

Ngelishwa, ujongano lweenkqubo ezininzi zokusebenza alubonisi icodec esetyenziswa naphi na. Ulwazi malunga noku lufumaneka kuphela kwi-Android, ukuqala kwinguqulo 8, kunye ne-macOS. Nangona kunjalo, nakwezi OS, kuphela ezo codecs ezixhaswa yifowuni / ikhompyuter kunye nee-headphones ziya kuboniswa.

Ungafumanisa njani ukuba zeziphi iicodecs ezixhaswa sisixhobo sakho? Rekhoda kwaye uhlalutye ukulahlwa kwetrafikhi ngeeparamitha ze-A2DP thethwano!
Oku kunokwenziwa kwiLinux, macOS kunye neAndroid. Kwi-Linux ungasebenzisa iWireshark okanye i-hcidump, kwi-macOS ungasebenzisa iBluetooth Explorer, kwaye kwi-Android ungasebenzisa umsebenzi oqhelekileyo wokulahla wokulahla weBluetooth HCI, okhoyo kwizixhobo zomphuhlisi. Uya kufumana ukulahla kwifomathi ye-btsnoop, enokulayishwa kwi-Wireshark analyzer.
Nika ingqalelo: indawo yokulahla echanekileyo inokufumaneka kuphela ngokuqhagamshela kwifowuni/ikhompyuter yakho ukuya kwii-headphone/izithethi (kungakhathaliseki ukuba zivakala zihlekisa kangakanani na)! I-headphones inokuzimela ngokuzimeleyo uxhulumaniso kunye nefowuni, apho baya kucela uluhlu lwee-codecs kwifowuni, kwaye kungekhona ngokufanayo. Ukuqinisekisa ukuba ukulahla okuchanekileyo kurekhodiweyo, qala ngokukhulula isixhobo uze udibanise ifowuni yakho nee-headphone ngelixa urekhoda indawo yokulahla.

Sebenzisa esi sihluzo silandelayo ukuhluza itrafikhi engabalulekanga:

btavdtp.signal_id

Ngenxa yoko, kuya kufuneka ubone into efana nale:

Ungacofa into nganye kumyalelo weGetCapabilities ukujonga iimpawu ezineenkcukacha zekhowudi.

I-Wireshark ayizazi zonke izichongi ze-codec, ngoko ke ezinye ii-codecs kuya kufuneka zicocwe ngokufihlakeleyo ngesandla, kujongwe kwitheyibhile yesazisi engezantsi:

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

Ukuze ndingahlalutyi ukulahla ngesandla, ndenze inkonzo eya kuhlalutya yonke into ngokuzenzekelayo: btcodecs.valdikss.org.ru

Ukuthelekiswa kwee-codecs. Yeyiphi icodec engcono?

Ikhowudi nganye ineengenelo kunye nokungona kwayo.
I-aptX kunye ne-aptX HD zisebenzisa iiprofayili ezinekhowudi ezinzima ezingenakutshintshwa ngaphandle kokuguqula i-encoder kunye ne-decoder. Akukho namnye umenzi wefowuni okanye umenzi we-headphone onokutshintsha i-bitrate okanye i-aptX encoding factor. Umnini we-codec, i-Qualcomm, inika i-encoder yereferensi ngendlela yethala leencwadi. Ezi nyaniso zinamandla e-aptX - uyazi kwangaphambili ukuba loluphi umgangatho wesandi oya kuwufumana, ngaphandle kwe "buts".

I-SBC, ngokuchaseneyo, ineeparamitha ezininzi ezilungiselelwayo, i-bitrate eguqukayo (i-encoder inokunciphisa iparamitha ye-bitpool ukuba amaza omoya axakekile), kwaye ayinazo iiprofayili ezinekhowudi eziqinileyo, kuphela “umgangatho ophakathi” ocetyiswayo kunye “nomgangatho ophezulu” owawu yongezwe kwinkcazo ye-A2DP ngo-2003 ngonyaka. "Umgangatho ophezulu" awusekho ukuba phezulu kwimigangatho yanamhlanje, kwaye ininzi ye-Bluetooth stacks ayikuvumeli ukuba usebenzise iiparitha ezingcono kuneprofayili "yomgangatho ophezulu", nangona kungekho zithintelo zobugcisa kule nto.
I-Bluetooth SIG ayinayo ireferensi ye-SBC encoder njengethala leencwadi, kwaye abavelisi baphumeza ngokwabo.
Obu bubuthathaka be-SBC - ayikaze icace kwangaphambili ukuba yeyiphi isandi esinokulindela kwisixhobo esithile. I-SBC inokuvelisa zombini i-audio ephantsi kunye nephezulu kakhulu, kodwa le yokugqibela ayinakufumaneka ngaphandle kokukhubaza okanye ukudlula imida eyenziweyo ye-Bluetooth stacks.

Imeko kunye ne-AAC ayicacanga: kwelinye icala, i-codec kufuneka ivelise umgangatho ongenakulinganiswa nowokuqala, kodwa ekusebenzeni, ngokugweba ngovavanyo lwebhubhoratri ye-SoundGuys kwizixhobo ezahlukeneyo ze-Android, oku akuqinisekiswanga. Eyona nto inokwenzeka kukuba, impazamo ikumgangatho ophantsi weekhowudi zeaudio ezakhelwe kwiichipsets ezahlukeneyo zefowuni. Kunengqiqo ukusebenzisa i-AAC kuphela kwizixhobo ze-Apple, kwaye kwi-Android ukuyikhawulela kwi-aptX kunye ne-LDAC.

I-Hardware exhasa ezinye ii-codec zithande ukuba kumgangatho ophezulu, ngenxa yokuba kwizixhobo ezingabizi kakhulu, ezikumgangatho ophantsi, akukho ngqiqweni ukuhlawula imirhumo yelayisensi yokusebenzisa ezo codecs. Kuvavanyo lwam, i-SBC ivakala kakuhle kakhulu kwizixhobo ezisemgangathweni.

Ndenze inkonzo yewebhu efaka i-audio kwi-SBC, i-aptX kunye ne-aptX HD ngexesha lokwenyani, kanye kwisikhangeli. Ngayo, unokuvavanya ezi codecs ngaphandle kokuhambisa iaudiyo ngeBluetooth, nakweyiphi na i-headsets eneentambo, izithethi, kunye nomculo owuthandayo, kwaye utshintshe iiparameters ze-encoding ngokuthe ngqo ngelixa udlala iaudio:
btcodecs.valdikss.org.ru/sbc-encoder
Inkonzo isebenzisa iilayibrari zekhowudi ze-SBC ezivela kwiprojekthi ye-BlueZ kunye ne-libopenaptx esuka kwi-ffmpeg, ehlanganiswe kwi-WebAssembly kunye ne-JavaScript ukusuka kwi-C, nge-emscripten, ukuqhuba kwi-browser. Ngubani onokuphupha ngekamva elinjalo!

Nantsi indlela ebonakala ngayo:

Qaphela indlela inqanaba lengxolo elitshintsha ngayo emva kwe-20 kHz kwiikhowudi ezahlukeneyo. Ifayile yeMP3 yoqobo ayiqulathanga amaza angaphezu kwama-20 kHz.

Zama ukutshintsha ii-codecs kwaye ubone ukuba uyawuva na umahluko phakathi kweyoqobo, i-SBC 53 Joint Stereo (iprofayile esemgangathweni kunye neyona ixhaphakileyo), kunye ne-aptX/aptX HD.

Ndiyawuva umahluko phakathi kwee-codecs kwii-headphones!

Abantu abangevayo umahluko phakathi kwee-codecs ngexesha lovavanyo ngenkonzo yewebhu bathi bayayiva xa bephulaphule umculo kwii-headphones ezingenazingcingo. Yeha, oku ayisiyonto yokudlala okanye isiphumo se-placebo: umahluko uyavakala ngokwenene, kodwa awubangwa ngumahluko. iikhowudi.

Uninzi lwee-chipsets zomsindo weBluetooth ezisetyenziswa kwizixhobo zokufumana ezingenazingcingo zixhotyiswe ngeDijithali Signal Processor (DSP), esebenzisa i-equalizer, compander, stereo expander, kunye nezinye izinto ezenzelwe ukuphucula (okanye ukutshintsha) isandi. Abavelisi bezixhobo zeBluetooth banokumisela iDSP kwikhowudi nganye ngokwahlukeneyo, kwaye xa utshintshela phakathi kwee-codecs, umphulaphuli uya kucinga ukuba uva umehluko ekusebenzeni kwee-codecs, xa ngokwenene bephulaphule izicwangciso ezahlukeneyo ze-DSP.

Umbhobho wokusetyenzwa komsindo we-DSP Kalimba kwiitshiphusi ezenziwe yiCSR/Qualcomm

Vula imisebenzi eyahlukeneyo ye-DSP yekhowudi nganye kunye nemveliso ngokwahlukeneyo

Ezinye izixhobo zeprimiyamu ziza nesoftware ekuvumela ukuba wenze useto lwe-DSP ngokwezifiso, kodwa uninzi lwee-headphones ezinexabiso eliphantsi azikwenzi, kwaye abasebenzisi abanako ukucima ukusetyenzwa kwe-audiyo ngesandla.

Iimpawu ezisebenzayo zezixhobo

Uguqulelo lwangoku lomgangatho we-A2DP unalo "Ulawulo lwevolumu epheleleyo" umsebenzi - Ukulawulwa kwevolumu yesixhobo usebenzisa imiyalelo ekhethekileyo ye-protocol ye-AVRCP, elawula ukuzuzwa kwesigaba sokuphuma, endaweni yokunciphisa ngokwenkqubo umthamo womsindo womsindo. Ukuba xa utshintsha ivolumu kwii-headphones zakho, utshintsho aluvumelani nevolumu kwifowuni yakho, ke ii-headphones zakho okanye ifowuni ayixhasi eli nqaku. Kule meko, kunengqiqo ukuhlala uphulaphule umculo kunye nevolumu ephezulu kwifowuni, ukulungelelanisa ivolumu yokwenyani kunye namaqhosha e-headphone - kulo mzekelo, umlinganiselo wesignali ukuya kwingxolo uya kuba ngcono kunye nomgangatho womsindo. kufuneke Ku phezulu.
Enyanisweni, kukho iimeko ezibuhlungu. Kwi-headphones yam ye-RealForce OverDrive ye-D1 ye-SBC, i-compander eyomeleleyo ivuliwe, kwaye ukwandisa ivolumu kukhokelela ekunyuseni kwinqanaba lezandi ezizolileyo, ngelixa ivolumu yezandi eziphakamileyo ayitshintshi (umqondiso uxinzelelwe). Ngenxa yoku, kuya kufuneka ubeke ivolumu kwikhompyuter ibe malunga nesiqingatha, apho akukho siphumo soxinzelelo.
Ngokuqwalasela kwam, zonke ii-headphones ezineekhowudi ezongezelelweyo zixhasa umsebenzi wokulawula umthamo opheleleyo, ngokucacileyo le yenye yeemfuno zesatifikethi se-codec.

Ezinye ii-headphones zixhasa ukudibanisa izixhobo ezibini ngexesha elinye. Oku kukuvumela, umzekelo, ukumamela umculo kwikhompyuter yakho kwaye ufumane iifowuni kwifowuni yakho. Nangona kunjalo, kuya kufuneka wazi ukuba kule modi enye icodecs ivaliwe kwaye yi-SBC kuphela esetyenziswayo.

I-AVDTP 1.3 Umsebenzi wokuLibazisa iNgxelo ivumela ii-headphones ukuba zinxibelelane nokulibaziseka kwisixhobo sokuhambisa apho isandi sidlalwe khona. Oku kukuvumela ukuba ulungelelanise ulungelelwaniso lweaudio kunye nevidiyo ngelixa ujonga iifayile zevidiyo: ukuba kukho iingxaki ngokusasazwa kwerediyo, iaudio ayiyi kusala ngasemva kwevidiyo, kodwa ngokuchaseneyo, ividiyo iya kuthotywa ngumdlali wevidiyo de iaudio kunye nevidiyo zilungelelaniswe kwakhona.
Umsebenzi uxhaswa ngee-headphones ezininzi, i-Android 9+ kunye ne-Linux ene-PulseAudio 12.0+. Andazi ngenkxaso yolu phawu kwamanye amaqonga.

Unxibelelwano lwe-Bidirectional ngeBluetooth. Ukuhanjiswa kwelizwi.

Ukuhanjiswa kwezwi kwiBluetooth, i-Synchronous Connection Oriented (SCO) isetyenzisiwe - ukuhanjiswa kwe-synchronous kunye nothethathethwano lokuqala loqhagamshelo. Imowudi ikuvumela ukuba udlulise isandi kunye nelizwi ngokungqongqo ngokulandelelana, kunye nokuthumela okulinganayo kunye nokufumana isantya, ngaphandle kokulinda ukuqinisekiswa kokudluliselwa kunye nokuthumela kwakhona iipakethi. Oku kunciphisa ukulibaziseka ngokubanzi kokuhanjiswa kwe-audio kwijelo likanomathotholo, kodwa kubeka izithintelo ezinzulu kwisixa sedatha ehanjiswa ngeyunithi yexesha, kwaye kuchaphazela kakubi umgangatho.
Xa le modi isetyenziswa, zombini ilizwi kunye ne-audio zihanjiswa ngomgangatho ofanayo.
Ngelishwa, ukusukela ngo-2019, umgangatho welizwi ngaphezulu kweBluetooth usembi, kwaye akucaci ukuba kutheni iBluetooth SIG ingenzi nto ngayo.

CVSD

Ikhowudi yentetho ye-CVSD esisiseko yalungiswa ngo-2002, kwaye ixhaswa zizo zonke izixhobo zonxibelelwano zeBluetooth ezinamacala amabini. Ibonelela ngokuhanjiswa kweaudio kunye nesampulu yesampulu ye-8 kHz, ehambelana nomgangatho wefowuni eqhelekileyo enentambo.

Umzekelo wokurekhodwa kule codec.

mSBC

I-codec eyongezelelweyo ye-mSBC yalungiswa ngo-2009, kwaye ngo-2010 iitshiphusi ezisetyenziselwa ukuhanjiswa kwelizwi sele zivele. I-mSBC ixhaswa ngokubanzi zizixhobo ezahlukeneyo.
Oku akusiyo i-codec ezimeleyo, kodwa i-SBC eqhelekileyo ukusuka kwinqanaba le-A2DP, kunye neprofayili ye-encoding esisigxina: 16 kHz, mono, bitpool 26.

Umzekelo wokurekhodwa kule codec.

Ayiqaqambi, kodwa ingcono kakhulu kune-CVSD, kodwa kusengumsebenzi ocaphukisayo ukusebenzisa unxibelelwano lwe-intanethi, ngakumbi xa usebenzisa i-headphones ukunxibelelana nomdlalo-iaudio yomdlalo nayo iya kuhanjiswa ngesantya sesampulu se-16 kHz.

Inkampani ye-FastStreamCSR yagqiba ekubeni iphuhlise umbono wokusebenzisa i-SBC. Ukujikeleza imida ye-SCO protocol kunye nokusebenzisa i-bitrate ephezulu, i-CSR yahamba ngendlela eyahlukileyo - bazisa inkxaso yeendlela ezimbini ze-SBC zomsindo kwi-A2DP yendlela enye yokuhambisa i-audio standard, iiprofayili ezisemgangathweni ze-encoding, kwaye bayibiza ngokuthi "FastStream".

I-FastStream ihambisa i-audio ye-stereo kwi-44.1 okanye i-48 kHz ene-bitrate ye-212 kbps kwizithethi, kunye ne-mono, i-16 kHz, ene-bitrate ye-72 kbps isetyenziselwa ukuhambisa i-audio ukusuka kwi-microphone (ingcono kancinane kune-mSBC). Iiparamitha ezinjalo zilungele ngakumbi ukunxibelelana kwimidlalo ye-intanethi - isandi somdlalo kunye nabangeneleli baya kuba kumgangatho ophezulu.

Umzekelo wokurekhodwa kule codec (+ isandi esisuka kumakrofoni, siyafana ne-msBC).

Inkampani yeza nentonga enomdla, kodwa ngenxa yokuba iphikisana nomgangatho we-A2DP, ixhaswa kuphela kwezinye ii-transmitters zenkampani (ezisebenza njengekhadi le-audio ye-USB, kungekhona isixhobo seBluetooth), kodwa ayenzi. fumana inkxaso kwizitaki zeBluetooth nangona inani lee-headphones ezinenkxaso ye-FastStream ayincinci kangako.

Okwangoku, inkxaso ye-FastStream kwi-OS kuphela njengesiqwenga seLinux PulseAudio ukusuka kumphuhlisi uPali Rohár, ongabandakanywanga kwisebe eliphambili leprogram.

I-aptX iLatency ephantsi

Okothusayo kukuba, i-aptX Low Latency ikwaxhasa iaudio ye-bidirectional, iphumeza umgaqo ofanayo njenge-FastStream.
Akunakwenzeka ukusebenzisa olu phawu lwekhowudi naphi na - akukho nkxaso ye-Low Latency decoding kuyo nayiphi na i-OS okanye nakweyiphi na i-Bluetooth stack eyaziwayo kum.

I-Bluetooth 5, i-Classic and Low Energy

Kubekho ukudideka okuninzi malunga neenkcukacha zeBluetooth kunye neenguqulelo ngenxa yobukho bemigangatho emibini engahambelaniyo phantsi kophawu olufanayo, zombini zisetyenziselwa iinjongo ezahlukeneyo.

Kukho iiprotocol ezimbini ezahlukeneyo, ezingahambelaniyo zeBluetooth: IBluetooth Classic kunye neBluetooth Low Energy (LE, ekwabizwa ngokuba yiBluetooth Smart). Kukho neprotocol yesithathu, i-Bluetooth High Speed, kodwa ayisasazeki kwaye ayisetyenziswa kwizixhobo zasekhaya.

Ukuqala ngeBluetooth 4.0, utshintsho kwinkcazo echaphazelekayo ikakhulu iBluetooth Low Energy, kunye nenguqulo yeClassic ifumene uphuculo oluncinci kuphela.

Uluhlu lotshintsho phakathi kweBluetooth 4.2 kunye neBluetooth 5:

9 UTSHINTSHO UKUSUKA KWI-v4.2 UKUYA 5.0

9.1 IIMPAWU EZINTSHA

Izinto ezininzi ezitsha ziyaziswa kwi-Bluetooth Core Specification 5.0 Release. Iindawo eziphambili zokuphucula zezi:
• Imaski yokuFumana indawo (SAM)
• 2 Msym/s PHY ye-LE
•LE Uluhlu olude
• UMjikelo oPhakamileyo weNtengiso engaDibanisiyo
• Izandiso zeNtengiso ze-LE
• I-Algorithm yoKhetho lwesitishi #2
9.1.1 Iimpawu ezongeziweyo kwi-CSA5 - Idityaniswe kwi-v5.0
•Amandla oPhumo oluPhezulu

umthombo: www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=421043 (iphepha 291)

Inye kuphela utshintsho oluchaphazelayo inguqulo yeClassic ngaphakathi kwesakhelo se-Bluetooth 5 yokucaciswa: bongeze inkxaso ye-Slot Availability Mask (SAM) ubuchwepheshe, eyenzelwe ukuphucula ukwahlulwa kosasazo lwerediyo. Lonke olunye utshintsho luchaphazela kuphela iBluetooth LE (kunye namandla oPhumo oluPhezulu kakhulu).

bonke Izixhobo zesandi zisebenzisa iBluetooth Classic kuphela. Akunakwenzeka ukudibanisa i-headphones kunye nezithethi ngeBluetooth Low Energy: akukho mgangatho wokuhambisa umsindo usebenzisa i-LE. Umgangatho we-A2DP, osetyenziselwa ukuhambisa umgangatho ophezulu womsindo, usebenza kuphela ngeBluetooth Classic, kwaye akukho analogue kwi-LE.

Isiphelo - ukuthenga izixhobo zomsindo ngeBluetooth 5 kuphela ngenxa yenguqu entsha yeprotocol ayinanto. IBluetooth 4.0/4.1/4.2 kumxholo wokuhanjiswa komsindo kuya kusebenza ngokufanayo.
Ukuba isibhengezo see-headphones ezintsha sikhankanya uluhlu oluphindwe kabini lokusebenza kunye nokunciphisa ukusetyenziswa kwamandla ngokubonga kwiBluetooth 5, ngoko kufuneka wazi ukuba mhlawumbi abayiqondi ngokwabo okanye bayalahlekisa. Akumangalisi, kuba nabavelisi beetshiphu zeBluetooth kwizibhengezo zabo babhidekile malunga nomahluko phakathi kwenguqulelo entsha yomgangatho, kwaye ezinye iitshiphusi zeBluetooth 5 zixhasa uguqulelo lwesihlanu kuphela kwi-LE, kwaye sebenzisa i-4.2 yeClassic.

Ukulibaziseka kokuhanjiswa kweAudio

Ubungakanani bokulibaziseka (i-lag) kwi-audio ixhomekeke kwizinto ezininzi: ubukhulu be-buffer kwi-audio stack, kwi-Bluetooth stack nakwisixhobo sokudlala esingenazingcingo ngokwaso, kunye nokulibaziseka kwe-algorithmic ye-codec.

I-latency yee-codecs ezilula ezifana ne-SBC, i-aptX kunye ne-aptX HD incinci kakhulu, i-3-6 ms, enokungahoywa, kodwa i-codecs eyinkimbinkimbi njenge-AAC kunye ne-LDAC inokubangela ukuba i-lag ibonakale. I-AAC algorithmic latency ye-44.1 kHz yi-60 ms. I-LDAC - malunga ne-30 ms (ngokusekwe kuhlalutyo oluqatha lwekhowudi yomthombo. Ndingaphosakela, kodwa hayi kakhulu.)

Isiphumo se-latency sixhomekeke kakhulu kwisixhobo sokudlala, i-chipset yayo kunye ne-buffer. Ngexesha lovavanyo, ndifumene ukusasazeka kwe-150 ukuya kwi-250 ms kwizixhobo ezahlukeneyo (kunye ne-codec ye-SBC). Ukuba sicinga ukuba izixhobo ezixhasa ii-codecs ezongezelelweyo i-aptX, i-AAC kunye ne-LDAC zisebenzisa izinto ezikumgangatho ophezulu kunye nesayizi encinci ye-buffer, sifumana oku kulandelayo okuqhelekileyo:

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

Makhe ndikukhumbuze: i-aptX Low Latency ayixhaswanga kwiinkqubo zokusebenza, yiyo loo nto i-latency ephantsi inokufumaneka kuphela nge-transmitter + receiver okanye i-transmitter + headphones / isithethi esidibeneyo, kwaye zonke izixhobo kufuneka zixhase le codec.

Isixhobo seBluetooth, isatifikethi, kunye nemiba yelogo

Indlela yokwahlula isixhobo somsindo esikumgangatho ophezulu kubuchule obuphantsi? Ngembonakalo, okokuqala!

Ngee-headsets zaseTshayina ezitshiphu, izithethi kunye nabamkeli:

1. Igama elithi "Bluetooth" alikho kwibhokisi kunye nesixhobo, "I-Wireless" kunye ne "BT" isetyenziswa rhoqo
2. Ilogo yeBluetooth ayikho kwibhokisi okanye isixhobo
3. Akukho LED idanyazayo eluhlaza

Ukungabikho kwezi zinto kubonisa ukuba isixhobo asikaqinisekiswa, oku kuthetha ukuba sinokuba nomgangatho ophantsi kwaye sinengxaki. Ngokomzekelo, ii-headphones zeBluedio aziqinisekiswanga ngeBluetooth kwaye azihambisani ngokupheleleyo neenkcukacha ze-A2DP. Ngebengazange baphumelele isatifikethi.

Makhe siqwalasele izixhobo ezininzi kunye neebhokisi ezivela kuzo:

Zonke ezi zixhobo aziqinisekiswanga. Imiyalelo isenokuba nelogo kunye negama lobuchwepheshe beBluetooth, kodwa eyona nto ibalulekileyo kukuba zikwibhokisi kunye/okanye isixhobo ngokwaso.

Ukuba i-headphones okanye isithethi sakho sithi "i-Ze bluetooth dewise iqhagamshelwe ngempumelelo", oku akubonisi umgangatho wabo:

isiphelo

Ngaba iBluetooth ingathatha indawo ngokupheleleyo ii-headphones ezineentambo kunye nee-headsets? Iyakwazi, kodwa ngexabiso lomgangatho ophantsi womnxeba, ukonyuka kwe-audio latency enokucaphukisa kwimidlalo, kunye neqela leekhowudi zobunikazi ezifuna iimali zelayisensi kunye nokunyusa iindleko zokugqibela zazo zombini ii-smartphones kunye nee-headphones.

Intengiso yee-codecs ezizezinye yomelele kakhulu: i-aptX kunye ne-LDAC ziboniswa njengotshintsho ekudala lulindelwe kwi-SBC “eyaphelelwe lixesha nembi”, ephantse ibembi njengoko abantu becinga ukuba injalo.

Njengoko kwavela, ukulinganiselwa okwenziweyo kwi-Bluetooth stacks kwi-bitrate ye-SBC kunokugqithwa, ukwenzela ukuba i-SBC ayiyi kuba ngaphantsi kwe-aptX HD. Ndithathe inyathelo kwaye ndenza isiqwenga se-LineageOS firmware: Sitshintsha isitaki seBluetooth ukuphucula isandi kwii-headphones ngaphandle kwe-AAC, i-aptX kunye ne-LDAC codecs.

Ulwazi oluninzi lunokufumaneka kwiiwebhusayithi Isandi Guys и SoundExpert.

Ibhonasi: SBC reference encoder, A2DP bitstream ulwazi kunye neefayile zovavanyo. Le fayile ibikade ithunyelwe esidlangalaleni kwiwebhusayithi yeBluetooth, kodwa ngoku ifumaneka kuphela kumalungu eBluetooth SIG.

umthombo: www.habr.com