Ngenxa yokukhiqizwa okukhulu kwama-smartphones ngaphandle kwejekhi yomsindo engu-3.5 mm, ama-headphone e-Bluetooth angenantambo abe yindlela eyinhloko yabaningi yokulalela umculo nokuxhumana ngemodi yama-headphone.
Abakhiqizi bemishini engenantambo abahlale bebhala imininingwane yomkhiqizo enemininingwane, futhi izindatshana ezimayelana nomsindo we-Bluetooth ku-inthanethi ziyaphikisana, kwesinye isikhathi azilungile, azikhulumi ngazo zonke izici, futhi ngokuvamile zikopisha imininingwane efanayo engahambisani neqiniso.
Ake sizame ukuqonda umthetho olandelwayo, amandla ezitaki ze-Bluetooth OS, ama-headphone nezikhulumi, ama-codec e-Bluetooth omculo nenkulumo, thola ukuthi yini ethinta ikhwalithi yomsindo odlulisiwe nokubambezeleka, funda ukuqoqa nokukhipha ulwazi mayelana nama-codec asekelwayo nezinye idivayisi. amakhono.

TL; DR:

• I-SBC - i-codec evamile
• Ama-headphone ane-equalizer yawo kanye ne-post-processing ye-codec ngayinye ngokwehlukana
• I-aptX ayilungile njengoba ikhangisiwe
• I-LDAC imaketha i-bullshit
• Ikhwalithi yekholi isangeyinhle
• Ungakwazi ukushumeka izifaki khodi zomsindo u-C esipheqululini sakho ngokuzihlanganisa ku-WebAssembly usebenzisa i-emscripten, futhi ngeke zehle kakhulu.

Umculo nge-Bluetooth

Ingxenye esebenzayo ye-Bluetooth inqunywa amaphrofayili - ukucaciswa kwemisebenzi ethile. Ukusakazwa komculo we-Bluetooth kusebenzisa iphrofayili yekhwalithi ephezulu ye-A2DP yokudlulisa umsindo unidirectional. Izinga le-A2DP lamukelwa ngo-2003 futhi alikashintshi kakhulu kusukela lapho.
Ngaphakathi kwephrofayela, i-codec eyi-1 eyisibopho ye-SBC eyinkimbinkimbi yokubala, edalelwe i-Bluetooth ngokuqondile, kanye nezinye ezi-3 ezengeziwe zisezingeni. Kuyenzeka futhi usebenzise amakhodekhi angabhaliwe okusebenza kwakho.

Kusukela ngoJuni 2019 sikhona ku-xkcd yamahlaya ngamakhodekhi angu-14 A2DP:

• I-SBC ← ifane ku-A2DP, isekelwa yiwo wonke amadivayisi
• MPEG-1/2 Layer 1/2/3 ← ifane ku-A2DP: yaziwa kakhulu MP3, esetshenziswa kumabonakude wedijithali MP2, futhi akwaziwa MP1
• MPEG-2/4 AAC ← ifane ku-A2DP
• I-ATRAC ← i-codec endala yakwa-Sony, eyenziwe ifane ku-A2DP
• I-LDAC ← i-codec entsha yakwa-Sony
• i-aptX ← i-codec yango-1988
• i-aptX HD ← okufanayo ne-aptX, kuphela ngezinketho ezihlukile zombhalo wekhodi
• i-aptX Latency ephansi ← i-codec ehluke ngokuphelele, akukho ukuqaliswa kwesofthiwe
• i-aptX eguqukayo ← enye i-codec evela ku-Qualcomm
• FastStream ← i-pseudo codec, ukuguqulwa kwe-SBC okuphindwe kabili
• I-HWA LHDC ← i-codec entsha evela ku-Huawei
• I-Samsung HD ← isekelwa amadivayisi ama-2
• I-Samsung Scalable ← isekelwa amadivayisi ama-2
• I-Samsung UHQ-BT ← isekelwa amadivayisi ama-3

Kungani sidinga ama-codec nhlobo, ubuza, uma i-Bluetooth ine-EDR, evumela ukuthi udlulise idatha ngesivinini se-2 kanye ne-3 Mbit / s, futhi kumashaneli amabili we-16-bit PCM engacindezelwa, i-1.4 Mbit / s yanele?

Ukudluliswa kwedatha nge-Bluetooth

Kunezinhlobo ezimbili zokudluliswa kwedatha ku-Bluetooth: I-Asynchronous Connection Less (ACL) yokudlulisa okuhambisanayo ngaphandle kokusungulwa koxhumano, kanye ne-Synchronous Connection Oriented (SCO), yokudlulisa okuvumelanayo nezingxoxo zokuxhuma kuqala.
Ukudlulisa kwenziwa kusetshenziswa uhlelo lokuhlukanisa isikhathi nokukhetha umzila wokudlulisela wephakethe ngalinye ngokwehlukana (Frequency-Hop/Time-Division-Duplex, FH/TDD), okuyilapho isikhathi sihlukaniswa khona ngezikhawu ezingu-625-microsecond ezibizwa ngokuthi izikhala. Enye yezisetshenziswa idlulisela ngezikhala ezinenombolo elinganayo, enye ngezikhala ezinenombolo eyinqaba. Iphakethe elidlulisiwe lingathatha izikhala ezi-1, ezi-3 noma ezi-5, ngokuya ngosayizi wedatha kanye nohlobo olumisiwe lokudlulisela, kulokhu, ukudluliselwa kwedivayisi eyodwa kwenziwa ezindaweni ezilinganayo nezingavamile kuze kube sekupheleni kokudluliselwa. Sekukonke, amaphakethe angafika ku-1600 angatholwa futhi athunyelwe ngomzuzwana, uma ngalinye lithatha indawo engu-1, futhi womabili amadivaysi adlulisela futhi athole okuthile ngaphandle kokuma.

2 kanye ne-3 Mbit/s ye-EDR, engatholakala ezimemezelweni nakuwebhusayithi ye-Bluetooth, izinga eliphezulu lokudluliswa kwamashaneli layo yonke idatha isiyonke (kuhlanganise nezihloko zobuchwepheshe zazo zonke izivumelwano lapho idatha kufanele ifakwe khona), ngezindlela ezimbili. kanyekanye. Isivinini sangempela sokudlulisa idatha sizohluka kakhulu.

Ukuze kudluliswe umculo, kusetshenziswa indlela engavumelaniyo, cishe njalo kusetshenziswa amaphakethe afana ne-2-DH5 kanye ne-3-DH5, aphethe inani eliphakeme ledatha kumodi ye-EDR engu-2 Mbit/s kanye no-3 Mbit/s, ngokulandelana, futhi athatha isikhathi esingu-5. - ukwabelana Slots.

Ukumelwa okuhleliwe kokudluliswa kusetshenziswa izikhala ezi-5 ngedivayisi eyodwa ne-slot engu-1 ngenye (DH5/DH1):


Ngenxa yomgomo wokuhlukaniswa kwesikhathi kwamagagasi omoya, siphoqeleka ukuthi silinde i-625-microsecond time slot ngemva kokudlulisa iphakethe uma idivayisi yesibili ingadluliseli lutho kithi noma idlulisele iphakethe elincane, kanye nesikhathi esengeziwe uma idivayisi yesibili idlulisa. emaphaketheni amakhulu. Uma idivaysi engaphezu kweyodwa ixhunywe ocingweni (isibonelo, ama-headphone, amawashi nesongo sokuqina), isikhathi sokudlulisa sabelwa phakathi kwakho konke.

Isidingo sokuhlanganisa umsindo kumaphrothokholi wezokuthutha akhethekile i-L2CAP ne-AVDTP sithatha amabhayithi angu-16 ukusuka enanini eliphezulu elingase libe khona lokulayisha okulalelwayo okudlulisiwe.

Uhlobo lwephakheji
Inani lezikhala
Ubukhulu. inani lamabhayithi ephaketheni
Ubukhulu. inani lamabhayithi okukhokha kwe-A2DP
Ubukhulu. I-bitrate yokulayisha kwe-A2DP

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 kanye no-1429 kbps akwanele neze ukudlulisa umsindo ongacindezelwanga ngaphansi kwezimo zangempela, ngobubanzi obunomsindo obungu-2.4 GHz kanye nesidingo sokudlulisa idatha yesevisi. I-EDR 3 Mbit/s idinga amandla okudlulisa nomsindo emoyeni, ngakho-ke, ngisho nakumodi ye-3-DH5, ukuhanjiswa kwe-PCM okunethezekile akunakwenzeka, kuzohlala kukhona ukuphazamiseka kwesikhashana, futhi yonke into izosebenza kuphela ebangeni le-PCM. amamitha ambalwa.
Empeleni, ngisho nokusakaza komsindo okungu-990 kbit/s (LDAC 990 kbit/s) kunzima ukudlulisa.

Masibuyele kumakhodekhi.

I-SBC

I-Codec iyadingeka kuwo wonke amadivayisi asekela izinga le-A2DP. Ikhodekhi engcono kakhulu nembi kakhulu ngesikhathi esifanayo.

Imvamisa yesampula
Ikhono
I-Bitrate
Usekelo lokufaka ikhodi
Usekelo lokuqopha

16, 32, 44.1, 48 kHz
16 okuncane
10-1500 kbps
Wonke amadivayisi
Wonke amadivayisi

I-SBC iyikhodekhi elula neshesha ngekhompyutha, enemodeli yakudala yengqondo (kusetshenziswa ukuvala imisindo ethule kuphela), kusetshenziswa i-adaptive pulse code modulation (APCM).
Ukucaciswa kwe-A2DP kuncoma amaphrofayili amabili azosetshenziswa: Ikhwalithi Ephakathi kanye Nekhwalithi Ephezulu.


I-codec inezilungiselelo eziningi ezikuvumela ukuthi ulawule ukubambezeleka kwe-algorithmic, inani lamasampula kubhulokhi, i-algorithm yokusabalalisa kancane, kodwa cishe yonke indawo imingcele efanayo enconyiwe ekucacisweni isetshenziswa: I-Joint Stereo, amabhendi angama-8, amabhlogo ayi-16 uzimele womsindo, indlela yokusabalalisa ibhithi Loudness.
I-SBC isekela ushintsho oluguquguqukayo lwepharamitha ye-Bitpool, ethinta ngokuqondile i-bitrate. Uma amaza omoya evalekile, amaphakethe elahlekile, noma amadivaysi atholakala ezindaweni ezikude, umthombo womsindo unganciphisa i-Bitpool kuze kube yilapho ukuxhumana kubuyela kokujwayelekile.

Abakhiqizi abaningi bama-headphone babeka inani eliphezulu le-Bitpool ku-53, elikhawulela i-bitrate kumakhilobhithi angu-328 ngomzuzwana uma usebenzisa iphrofayela enconyiwe.
Noma ngabe umkhiqizi wama-headphone usethe inani eliphezulu le-Bitpool ngaphezu kwama-53 (amamodeli anjalo ayatholakala, isibonelo: I-Beats Solo³, i-JBL Everest Elite 750NC, i-Apple AirPods, nayo itholakala kwezinye izamukeli namayunithi ekhanda lemoto), ngakho-ke iningi le-OS ngeke livumele. ukusetshenziswa kwama-bitrate anyukile ngenxa yokusetha umkhawulo wenani langaphakathi kuzitaki ze-Bluetooth.
Ukwengeza, abanye abakhiqizi babeka inani eliphakeme le-Bitpool libe phansi kwamanye amadivayisi. Isibonelo, kuBluedio T ingama-39, ku-Samsung Gear IconX ingu-37, enikeza ikhwalithi yomsindo ephansi.

Imikhawulo yokwenziwa engxenyeni yonjiniyela bezitaki ze-Bluetooth okungenzeka kakhulu yavela ngenxa yokungahambelani kwamanye amadivayisi anamanani amakhulu e-Bitpool noma amaphrofayili angavamile, noma ngabe babike ukusekela kwabo, kanye nokuhlolwa okunganele ngesikhathi sokunikezwa isitifiketi. Kube lula kubabhali bezitaki ze-Bluetooth ukuzikhawulela ekuvumeleni iphrofayili enconyiwe, kunokudala imininingwane yolwazi yamadivayisi angalungile (nakuba manje benza lokhu kweminye imisebenzi esebenza ngokungalungile).

I-SBC inika amandla amabhithi wokulinganisa kumabhendi wefrikhwensi ngokwesisekelo esiphansi ukuya phezulu, ngezisindo ezihlukile. Uma yonke i-bitrate isetshenziswe kumafrikhwensi aphansi naphakathi, amaza aphezulu "azonqunywa" (kuyoba nokuthula esikhundleni salokho).

Isibonelo se-SBC 328 kbps. Phezulu kukhona okwangempela, ngezansi kune-SBC, eshintsha ngezikhathi ezithile phakathi kwamathrekhi. Umsindo osefayela levidiyo usebenzisa i-FLAC codec yokucindezelwa okungalahleki. Ukusebenzisa i-FLAC esitsheni se-mp4 akumiswanga ngokusemthethweni, ngakho-ke akuqinisekisiwe ukuthi isiphequluli sakho sizoyidlala, kodwa kufanele isebenze kuzinguqulo zakamuva zedeskithophu ye-Chrome ne-Firefox. Uma ungenawo umsindo, ungalanda ifayela futhi ulivule esidlali sevidiyo esigcwele.
ZZ Phezulu - Indoda Egqokile Ebukhali

I-spectrogram ibonisa isikhathi sokushintshwa: I-SBC ngezikhathi ezithile inqamula imisindo ethulile ngaphezu kuka-17.5 kHz, futhi ayinikezi nhlobo amabhithi ebhendi ngaphezu kuka-20 kHz. I-spectrogram ephelele iyatholakala ngokuchofoza (1.7 MB).

Angiwuzwa umehluko phakathi kweyokuqala ne-SBC kule ngoma.

Ake sithathe okuthile okusha futhi silingise umsindo obuzotholwa kusetshenziswa ama-headphone e-Samsung Gear IconX nge-Bitpool 37 (ngenhla - isiginali yoqobo, ngezansi - SBC 239 kbps, umsindo ku-FLAC).
Ukuzithokozisa Okungenangqondo - Fakaza

Ngizwa ukuklayeka, umthelela omncane we-stereo kanye nomsindo ongajabulisi othi "clunking" kumafrikhwensi aphezulu wephimbo.

Nakuba i-SBC iyikhodekhi evumelana nezimo kakhulu, ingalungiselelwa ukubambezeleka okuphansi, inikeza ikhwalithi yomsindo enhle kakhulu kuma-bitrate aphezulu (452+ kbps) futhi ilungele abantu abaningi Ngekhwalithi Ephakeme evamile (328 kbps), ngenxa yokuthi lokho izinga le-A2DP alicacisi amaphrofayli angaguquki (kodwa linikeza izincomo kuphela), abathuthukisi be-stack babeke imingcele yokwenziwa ku-Bitpool, imingcele yomsindo odlulisiwe ayivezwa ku-interface yomsebenzisi, futhi abakhiqizi bama-headphone bakhululekile ukusetha izilungiselelo zabo futhi bangalokothi. khombisa inani le-Bitpool ekucacisweni kobuchwepheshe bomkhiqizo, i-codec yaduma ngekhwalithi yayo ephansi yomsindo, nakuba lokhu akuyona inkinga nge-codec kanjalo.
Ipharamitha ye-Bitpool ithinta ngokuqondile i-bitrate kuphela ngaphakathi kwephrofayela eyodwa. Inani elifanayo le-Bitpool 53 linganikeza kokubili i-bitrate engu-328 kbps ngephrofayili Enconyiwe Yekhwalithi Ephezulu, kanye ne-1212 kbps ene-Dual Channel kanye namabhendi ama-frequency angu-4, yingakho ababhali be-OS, ngaphezu kwemikhawulo ku-Bitpool, bebeka umkhawulo futhi baqhubeke. I-Bitrate. Njengoba ngibona, lesi simo savela ngenxa yephutha ezingeni le-A2DP: kwakudingeka ukuxoxisana nge-bitrate, hhayi i-Bitpool.

Ithebula lokusekelwa kwamakhono e-SBC kuma-OS ahlukene:

I-ОС
Amanani amasampula asekelwe
Umkhawulo ubuningi. I-Bitpool
Umkhawulo ubuningi. I-Bitrate
I-Bitrate ejwayelekile
Ukulungiswa okuguquguqukayo kwe-Bitpool

Windows 10
I-44.1 кГц
53
512 kbps
328 kbps
✓*

I-Linux (BlueZ + PulseAudio)
16, 32, 44.1, 48 kHz
64 (ngokuxhumana okungenayo), 53 (ngokuxhumana okuphumayo)
Awukho umkhawulo
328 kbps
✓*

i-MacOS High Sierra
I-44.1 кГц
64, okuzenzakalelayo 53***
Akwaziwa
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
I-48 кГц
53
Awukho umkhawulo
328 kbps
✗

* I-Bitpool iyancipha kuphela, kodwa ayikhuli ngokuzenzakalelayo, uma izimo zokudlulisa ziba ngcono. Ukuze ubuyisele i-Bitpool udinga ukumisa ukudlala, linda imizuzwana embalwa bese uqala umsindo futhi.
** Inani elizenzakalelayo lincike kuzilungiselelo zesitaki ezicaciswe lapho kuhlanganiswa i-firmware. Ku-Android 8/8.1 imvamisa ingu-44.1 kHz noma 48 kHz kuphela, kuye ngezilungiselelo ngesikhathi sokuhlanganiswa, kwezinye izinguqulo 44.1 kHz kanye no-48 kHz kusekelwa ngesikhathi esisodwa.
*** Inani le-Bitpool lingakhushulwa kuhlelo lwe-Bluetooth Explorer.

I-aptX ne-aptX HD

I-aptX iyi-codec elula futhi esheshayo yekhompyutha, ngaphandle kwe-psychoacoustics, isebenzisa ukuguquguquka kwekhodi ye-pulse eguquguqukayo (I-ADPCM). Ivele cishe ngo-1988 (usuku lokufaka ilungelo lobunikazi yangomhla ka-February 1988), ngaphambi kwe-Bluetooth, yayisetshenziswa ngokuyinhloko emishinini yomsindo engenazintambo. Okwamanje okuphethwe yi-Qualcomm, kudinga amalayisense kanye nezinzuzo. Kusukela ngo-2014: $6000 ngesikhathi esisodwa futhi ≈$1 idivayisi ngayinye, ngamaqoqo angafika kumadivayisi angu-10000 (umthombo, k. 16).
I-aptX kanye ne-aptX HD amakhodekhi afanayo, anamaphrofayili ombhalo ahlukene.

I-codec inepharamitha eyodwa kuphela - ukukhetha imvamisa yesampula. Kukhona, nokho, ukukhetha kwenombolo/imodi yamashaneli, kodwa kuwo wonke amadivayisi engiwaziyo (izingcezu ezingu-70+) kuphela i-Stereo esekelwayo.

Ikhodekhi
Imvamisa yesampula
Ikhono
I-Bitrate
Usekelo lokufaka ikhodi
Usekelo lokuqopha

i-aptX
16, 32, 44.1, 48 kHz
16 okuncane
128 / 256 / 352 / 384 kbps (kuya ngezinga lamasampula)
Windows 10 (ideskithophu neselula), i-macOS, i-Android 4.4+/7*, i-Blackberry OS 10
Uhlu olubanzi lwemishini yomsindo (i-hardware)

* Izinguqulo ezifika ku-7 zidinga ukuguqulwa kwesitaki se-Bluetooth. Ikhodekhi isekelwa kuphela uma umkhiqizi wedivayisi ye-Android enelayisensi yekhodekhi evela ku-Qualcomm (uma i-OS inamalabhulali ombhalo wekhodi).

I-aptX ihlukanisa umsindo ube amabhendi amafrikhwensi angu-4 futhi iwalinganise ngenani elifanayo lamabhithi njalo: amabhithi angu-8 angu-0-5.5 kHz, amabhithi angu-4 angu-5.5-11 kHz, amabhithi angu-2 angu-11-16.5 kHz, amabhithi angu-2 ngo-16.5-22 kHz ( izibalo zesilinganiso samasampula 44.1 kHz).

Isibonelo somsindo we-aptX (phezulu - isiginali yoqobo, ezansi - i-aptX, ama-spectrogram eziteshi ezingakwesokunxele kuphela, umsindo ku-FLAC):

Ukuphakama kwaba bomvu kancane, kodwa wawungezwa umehluko.

Ngenxa yokusabalalisa okugxilile kwamabhithi wokulinganisa, i-codec ayikwazi "ukushintsha izingcezu" iye kumafrikhwensi awadinga kakhulu. Ngokungafani ne-SBC, i-aptX ngeke “isike” amaza, kodwa izongeza umsindo we-quantization kuwo, yehlise ububanzi obuguquguqukayo bomsindo.

Akufanele kucatshangwe ukuthi ukusebenzisa, isibonelo, amabhithi angu-2 ngebhendi ngayinye kunciphisa ububanzi obuguquguqukayo bube ngu-12 dB: I-ADPCM ivumela kufika ku-96 dB wobubanzi obuguquguqukayo ngisho nalapho kusetshenziswa amabhithi we-quantization angu-2, kodwa kuphela isignali ethile.
I-ADPCM igcina umehluko wezinombolo phakathi kwesampula yamanje nesampula elandelayo, esikhundleni sokugcina inani eliphelele njengaku-PCM. Lokhu kukuvumela ukuthi wehlise izidingo zenani lamabhithi adingekayo ukuze ugcine okufanayo (ngaphandle kokulahlekelwa) noma cishe okufanayo (ngephutha elincane lokusondeza) ulwazi. Ukunciphisa amaphutha okuzungeza, amathebula e-coefficient asetshenziswa.
Lapho bedala i-codec, ababhali babale ama-coefficient e-ADPCM kusethi yamafayela omsindo omculo. Uma isignali yomsindo isondela kusethi yomculo okwakhiwe kuwo amatafula, amaphutha amancane okulinganisa (umsindo) ayakha i-aptX.

Ngenxa yalokhu, ukuhlolwa kokwenziwa kuzohlale kuveza imiphumela emibi kunomculo. Ngenze isibonelo esikhethekile sokwenziwa lapho i-aptX ikhombisa imiphumela engemihle - i-sine wave ene-frequency engu-12.4 kHz (ngenhla - isignali yoqobo, ngezansi - i-aptX. Umsindo ku-FLAC. Yehlisa ivolumu!):

Igrafu ye-Spectrum:


Imisindo izwakala kahle.

Kodwa-ke, uma ukhiqiza i-sine wave nge-amplitude encane ukuze ithule, umsindo uzophinde uthule, ubonise ububanzi obuhlukahlukene bokuguquguquka:

Ukuze uzwe umehluko phakathi kwengoma yokuqala necindezelwe, ungaguqula isignali eyodwa bese wengeza ishaneli yamathrekhi ngeshaneli. Le ndlela, ngokuvamile, ayilungile, futhi ngeke inikeze imiphumela enengqondo ngama-codec ayinkimbinkimbi, kodwa ikakhulukazi i-ADCMM ifaneleka impela.
Umehluko phakathi koqobo ne-aptX
Umehluko oyisikwele wempande wamasiginali usezingeni elingu -37.4 dB, elingelikhulu kumculo onjalo ocindezelwe.

i-aptX HD

I-aptX HD ayiyona i-codec ezimele - iphrofayili yombhalo wekhodi ethuthukisiwe ye-aptX codec. Izinguquko zithinte inani lamabhithi abelwe ububanzi befrikhwensi yombhalo wekhodi: amabhithi angu-10 ka-0-5.5 kHz, amabhithi angu-6 ka-5.5-11 kHz, amabhithi angu-4 ka-11-16.5 kHz, amabhithi angu-4 ngo-16.5-22 kHz (amadijithi angu-44.1 kHz). .

Ikhodekhi
Imvamisa yesampula
Ikhono
I-Bitrate
Usekelo lokufaka ikhodi
Usekelo lokuqopha

i-aptX HD
16, 32, 44.1, 48 kHz
24 amabhithi
192 / 384 / 529 / 576 kbps (kuya ngezinga lamasampula)
I-Android 8+*
Ezinye izisetshenziswa zomsindo (izingxenyekazi zekhompyutha)

* Izinguqulo ezifika ku-7 zidinga ukuguqulwa kwesitaki se-Bluetooth. Ikhodekhi isekelwa kuphela uma umkhiqizi wedivayisi ye-Android enelayisensi yekhodekhi evela ku-Qualcomm (uma i-OS inamalabhulali ombhalo wekhodi).

Akuvamile kune-aptX: ngokusobala idinga ilayisense ehlukene evela ku-Qualcomm, kanye nezindleko zelayisensi ezihlukene.

Ake siphinde isibonelo nge-sine wave ku-12.4 kHz:


Kungcono kakhulu kune-aptX, kodwa kusenomsindo omncane.

i-aptX Latency ephansi

Ikhodekhi evela ku-Qualcomm engahlangani ngalutho ne-aptX evamile ne-aptX HD, uma kubhekwa ulwazi olulinganiselwe oluvela kubantu abahilelekile ekuthuthukisweni kwayo. Idizayinelwe ukudlulisa okusebenzisanayo kwe-low-latency audio (amamuvi, imidlalo), lapho ukubambezeleka komsindo kungeke kulungiswe isofthiwe. Akukho ukufakwa kwesofthiwe okwaziwayo kwezifaki khodi namadekhoda; asekelwa ngokukhethekile izithumeli, izamukeli, ama-headphone nezipikha, kodwa hhayi ngama-smartphone namakhompyutha.

Imvamisa yesampula
I-Bitrate
Usekelo lokufaka ikhodi
Usekelo lokuqopha

I-44.1 кГц
276/420 kbps
Amanye ama-transmitter (hardware)
Ezinye izisetshenziswa zomsindo (izingxenyekazi zekhompyutha)

I-AAC

I-AAC, noma i-Advanced Audio Coding, iyikhodekhi eyinkimbinkimbi eyenziwe ngekhompyutha enemodeli ebucayi ye-psychoacoustic. Isetshenziselwa kakhulu umsindo ku-inthanethi, okwesibili ngokuduma ngemuva kwe-MP3. Idinga amalayisense kanye nezinzuzo: $15000 kanye (noma $1000 ezinkampanini ezinabasebenzi abangaphansi kuka-15) + $0.98 kumadivayisi okuqala angu-500000 (umthombo).
I-codec isezingeni phakathi kokucaciswa kwe-MPEG-2 kanye ne-MPEG-4, futhi ngokuphambene nombono oyiphutha ovamile, akuyona eka-Apple.

Imvamisa yesampula
I-Bitrate
Usekelo lokufaka ikhodi
Usekelo lokuqopha

8 - 96 kHz
8 - 576 kbps (ye-stereo), 256 - 320 kbps (okujwayelekile ku-Bluetooth)
macOS, Android 7+*, iOS
Uhlu olubanzi lwemishini yomsindo (i-hardware)

* kuphela kumadivayisi abakhiqizi bawo abakhokhe izimali zamalayisense

I-iOS ne-macOS zisebenzisa isishumeki se-AAC esingcono kakhulu se-Apple ukuletha ikhwalithi yomsindo ephezulu kakhulu. I-Android isebenzisa isifaki khodi sekhwalithi yesibili ephezulu ye-Fraunhofer FDK AAC, kodwa ingase isebenzise izingxenyekazi zekhompuyutha ezihlukahlukene ezakhelwe kungxenyekazi (i-SoC) enekhwalithi yombhalo wekhodi engaziwa. Ngokusho kokuhlolwa kwakamuva kuwebhusayithi ye-SoundGuys, ikhwalithi yombhalo wekhodi ye-AAC yamafoni ahlukene e-Android ayahluka kakhulu:

Amadivayisi amaningi alalelwayo angenantambo anesilinganiso esiphezulu se-bitrate esingu-320 kbps se-AAC, amanye asekela kuphela u-256 kbps. Amanye ama-bitrate ayivelakancane kakhulu.
I-AAC ihlinzeka ngekhwalithi enhle kakhulu kuma-bitrate angu-320 no-256 kbps, kodwa ingaphansi kwayo ukulahleka kombhalo wekhodi olandelanayo wokuqukethwe osekucindezelwe kakade, nokho, kunzima ukuzwa noma imuphi umehluko ngeyoqobo ku-iOS nge-bitrate engu-256 kbps ngisho nokubhalwa ngekhodi okukodwa okukodwa, isibonelo, i-MP3 320 kbps kuya ku-AAC 256 kbps, ukulahlekelwa kungashaywa indiva.
Njengamanye ama-codec e-Bluetooth, noma yimuphi umculo uqala ukukhishwa ikhodi bese ubhalwa ngekhodi. Uma ulalele umculo ngefomethi ye-AAC, iqala ikhishwe yi-OS, bese ibhalwa ngekhodi ku-AAC futhi ukuze idluliselwe nge-Bluetooth. Lokhu kuyadingeka ukuze kuxutshwe ukusakazwa komsindo okuningi, njengomculo nezaziso zemilayezo emisha. I-iOS injalo. Ku-inthanethi ungathola izitatimende eziningi ezithi kumculo we-iOS ngefomethi ye-AAC awudluliswa ikhodi uma udluliswa nge-Bluetooth, okungelona iqiniso.

MP1/2/3

Amakhodekhi omndeni we-MPEG-1/2 Part 3 aqukethe iMP3 eyaziwayo nesetshenziswa kakhulu, iMP2 engavamile kakhulu (esetshenziswa kakhulu kumabonakude wedijithali nomsakazo), kanye neMP1 engaziwa ngokuphelele.

Amakhodekhi amadala we-MP1 kanye ne-MP2 awasekelwa nhlobo: Angikwazanga ukuthola noma yimaphi ama-headphones noma isitaki se-Bluetooth ebesingasifaka ikhodi noma sikhiphe ikhodi.
Ukukhipha ikhodi kwe-MP3 kusekelwa amanye ama-headphone, kodwa umbhalo wekhodi awusekelwe kunoma yisiphi isitaki sesistimu yokusebenza. Kubonakala sengathi isitaki se-BlueSoleil somuntu wesithathu se-Windows singafaka ikhodi ku-MP3 uma ushintsha mathupha ifayela lokumisa, kodwa kimina ukulifaka kuholela ku-BSoD ku-Windows 10. Isiphetho - i-codec empeleni ayikwazi ukusetshenziselwa umsindo we-Bluetooth.
Ngaphambilini, ngo-2006-2008, ngaphambi kokusabalala kwezinga le-A2DP kumadivayisi, abantu babelalela umculo weMP3 kumahedisethi weNokia BH-501 ngohlelo lwe-MSI BluePlayer, olwalutholakala ku-Symbian ne-Windows Mobile. Ngaleso sikhathi, ukwakheka kwe-OS kwama-smartphones kwavumela ukufinyelela emisebenzini eminingi esezingeni eliphansi, futhi ku-Windows Mobile kwakungenzeka ngisho nokufaka izitaki ze-Bluetooth zenkampani yangaphandle.

Ilungelo lokugcina lobunikazi bekhodekhi ye-MP3 liphelelwe yisikhathi, ukusetshenziswa kwekhodekhi akudingi izindleko zelayisensi kusukela ngomhla ka-23 Ephreli 2017.

Uma ilungelo lobunikazi elisebenza isikhathi eside elishiwo kuzithenjwa ezishiwo ngenhla lithathwa njengesilinganiso, ubuchwepheshe be-MP3 bube bungenalo ilungelo lobunikazi e-United States ngomhla ka-April 16, 2017 lapho I-Patent yase-US 6,009,399, ephethwe futhi ilawulwa yi-Technicolor, iphelelwa yisikhathi.

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

Imvamisa yesampula
I-Bitrate
Usekelo lokufaka ikhodi
Usekelo lokuqopha

16 - 48 kHz
8 - 320 kbps
Ayisekelwa noma kuphi
Ezinye izisetshenziswa zomsindo (izingxenyekazi zekhompyutha)

I-LDAC

Ikhodekhi entsha nekhuthaziwe ye-“Hi-Res” evela kwa-Sony, esekela izilinganiso zesampula ezifika ku-96 kHz no-24-bit bitrate, nama-bitrate afika ku-990 kbps. Ikhangiswa njengekhodekhi ye-audiophile, esikhundleni samakhodekhi e-Bluetooth akhona. Inomsebenzi wokulungiswa kwe-bitrate okuguquguqukayo, kuye ngezimo zokusakaza zomsakazo.

Isifaki khodi se-LDAC (libldac) ifakiwe kuphakheji evamile ye-Android, ngakho ukubhala ngekhodi kusekelwa kunoma iyiphi i-smartphone ye-Android eqala nge-OS version 8. Awekho ama-decoder e-software atholakala ngokukhululekile, ukucaciswa kwe-codec akutholakali emphakathini jikelele, noma kunjalo, ekuboneni kuqala isishumeki sekhodi, isakhiwo sangaphakathi se-codec sifana I-ATRAC9 - Ikhodekhi yakwaSony esetshenziswe ku-PlayStation 4 ne-Vita: zombili zisebenza kusizinda samafrikhwensi, zisebenzisa i-modified discrete cosine transform (MDCT) kanye nokucindezelwa kusetshenziswa i-algorithm ye-Huffman.

Ukusekelwa kwe-LDAC kunikezwa cishe ngokukhethekile ngama-headphone avela kwa-Sony. Ikhono lokunquma i-LDAC kwesinye isikhathi litholakala kuma-headphone nama-DAC avela kwabanye abakhiqizi, kodwa akuvamile.

Imvamisa yesampula
I-Bitrate
Usekelo lokufaka ikhodi
Usekelo lokuqopha

44.1 - 96 kHz
303/606/909 kbit/s (ku-44.1 kanye no-88.2 kHz), 330/660/990 kbit/s (ku-48 kanye no-96 kHz)
I-Android 8 +
Amanye ama-headphone akwaSony namanye amadivaysi avela kwabanye abakhiqizi (i-hardware)

Ukumaketha i-LDAC njenge-codec ye-Hi-Res kulimaza ingxenye yayo yobuchwepheshe: kuwubuwula ukuchitha i-bitrate ekudluliseni amaza angezwakali endlebeni yomuntu nokwandisa ukujula kancane, kuyilapho akwanele ukudlulisa ikhwalithi ye-CD (44.1/16) ngaphandle kokulahlekelwa. . Ngenhlanhla, i-codec inezinhlobo ezimbili zokusebenza: ukudluliswa komsindo we-CD kanye nokudluliswa komsindo we-Hi-Res. Esimweni sokuqala, amabhithi angu-44.1 kHz/16 kuphela adluliselwa emoyeni.

Njengoba i-software ye-LDAC decoder ingatholakali mahhala, akunakwenzeka ukuhlola i-codec ngaphandle kwamadivaysi engeziwe akhipha ikhodi i-LDAC. Ngokwemiphumela yokuhlolwa kwe-LDAC ku-DAC ngokwesekwa kwayo, onjiniyela be-SoundGuys.com abaxhume ngokuphuma kwedijithali futhi baqopha umsindo ophumayo kumasignali okuhlola, i-LDAC 660 kanye ne-990 kbps ngemodi yekhwalithi ye-CD inikeza isignali-to- isilinganiso somsindo singcono kancane kuneso se-aptX HD.

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

I-LDAC futhi isekela ama-bitrate aguqukayo ngaphandle kwamaphrofayela amisiwe - ukusuka ku-138 kbps ukuya ku-990 kbps, kodwa ngokwazi kwami, i-Android isebenzisa kuphela amaphrofayili amisiwe angu-303/606/909 kanye no-330/660/990 kbps.

Amanye ama-codec

Amanye ama-codec e-A2DP awasetshenziswa kakhulu. Ukwesekwa kwabo cishe akukho ngokuphelele noma kutholakala kuphela kumamodeli athile wama-headphone nama-smartphone.
I-codec ye-ATRAC esezingeni ku-A2DP ayikaze isetshenziswe njengekhodekhi ye-Bluetooth ngisho nabakwaSony ngokwabo, i-Samsung HD, i-Samsung Scalable kanye ne-Samsung UHQ-BT codec inokusekelwa okulinganiselwe kakhulu ekuthumeleni nasekutholeni amadivaysi, futhi i-HWA LHDC yintsha kakhulu futhi isekelwa ezintathu kuphela. (?) amadivayisi.

Ukusekelwa kwe-Codec kwamadivayisi alalelwayo

Akubona bonke abakhiqizi abashicilela ulwazi olunembile mayelana nama-codec asekelwa ama-headphone athile angenawaya, izipikha, izemukeli noma izithumeli. Kwesinye isikhathi kuyenzeka ukuthi ukusekelwa kwekhodekhi ethile kungokudlulisa, kodwa hhayi okokwamukela (okufanelekile kuma-transmitters-receivers ahlanganisiwe), nakuba umenzi esho nje “ukwesekwa”, ngaphandle kwamanothi (ngicabanga ukuthi ukunikwa kwelayisensi okuhlukene kwezishumeki nama-decoder kwabanye ama-codecs anecala kulokhu). Kumadivayisi ashibhe kakhulu, ungase ungakutholi nhlobo ukwesekwa kwe-aptX okumenyezelwe.

Ngeshwa, ukuxhumana kwezinhlelo eziningi zokusebenza azibonisi i-codec esetshenziswa noma yikuphi. Ulwazi mayelana nalokhu lutholakala kuphela ku-Android, kusukela kunguqulo 8, kanye ne-macOS. Nokho, nakulawo ma-OS, lawo makhodekhi kuphela asekelwa yizingcingo/ikhompyutha nama-headphone azovezwa.

Ungathola kanjani ukuthi yimaphi ama-codec asekelwa idivayisi yakho? Rekhoda futhi uhlaziye ukulahlwa kwethrafikhi ngemingcele yezingxoxo ze-A2DP!
Lokhu kungenziwa ku-Linux, macOS kanye ne-Android. Ku-Linux ungasebenzisa i-Wireshark noma i-hcidump, ku-macOS ungasebenzisa i-Bluetooth Explorer, futhi ku-Android ungasebenzisa umsebenzi ojwayelekile wokulondoloza ukulahlwa kokulahlwa kwe-Bluetooth HCI, otholakala kumathuluzi kanjiniyela. Uzothola ukulahlwa ngefomethi ye-btsnoop, engalayishwa kusihlaziyi se-Wireshark.
Nakani: indawo yokulahla elungile ingatholwa kuphela ngokuxhuma kusuka kufoni/ikhompyutha yakho kuma-headphone/izipikha (kungakhathaliseki ukuthi kuzwakala kuhlekisa kanjani)! Ama-headphone angakwazi ukuzimela ngokuzimela ukuxhumana nefoni, lapho azocela uhlu lwama-codec ocingweni, hhayi ngokuphambene nalokho. Ukuqinisekisa ukuthi ukulahlwa okulungile kurekhodiwe, qala ngokunqamula idivayisi, bese ubhanqa ifoni nama-headphone ngenkathi uqopha ukulahlwa.

Sebenzisa isihlungi sokubonisa esilandelayo ukuze uhlunge ithrafikhi engabalulekile:

btavdtp.signal_id

Ngenxa yalokho, kufanele ubone okufanayo nalokhu:

Ungachofoza entweni ngayinye kumyalo we-GetCapabilities ukuze ubuke izici ezinemininingwane zekhodekhi.

I-Wireshark ayizazi zonke izihlonzi zekhodekhi, ngakho-ke amanye ama-codec kuzodingeka asuswe ukubethela ngesandla, kubhekwe ithebula lezihlonzi elingezansi:

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 ngingahlaziyi ukulahlwa ngesandla, ngenze isevisi ezohlaziya yonke into ngokuzenzakalelayo: btcodecs.valdikss.org.ru

Ukuqhathaniswa kwama-codec. Iyiphi i-codec engcono?

I-codec ngayinye inezinzuzo zayo kanye nokubi.
I-aptX ne-aptX HD zisebenzisa amaphrofayli anamakhodi aqinile angenakushintshwa ngaphandle kokushintsha isishumeki nesikhi khodi. Akekho umkhiqizi wefoni noma umkhiqizi wamahedfoni ongashintsha izici zombhalo ze-bitrate noma ze-aptX. Umnikazi wekhodekhi, i-Qualcomm, uhlinzeka ngesifaki khodi esiyisethenjwa ngendlela yelabhulali. Lawa maqiniso angamandla e-aptX - wazi kusengaphambili ukuthi iyiphi ikhwalithi yomsindo ozoyithola, ngaphandle kokuthi "buts".

I-SBC, ngokuphambene, inamapharamitha amaningi alungisekayo, i-bitrate eguquguqukayo (isifaki khodi singanciphisa ipharamitha ye-bitpool uma amaza omoya ematasa), futhi ingenawo amaphrofayili anekhodi eqinile, kuphela “ikhwalithi emaphakathi” kanye “nekhwalithi ephezulu” enconyiwe. yengezwe esimisweni se-A2DP ngonyaka ka-2003. "Ikhwalithi ephezulu" ayisaphezulu kangako ngezindinganiso zanamuhla, futhi izitaki eziningi ze-Bluetooth azikuvumeli ukuthi usebenzise imingcele kangcono kunephrofayili "yekhwalithi ephezulu", nakuba ingekho imingcele yezobuchwepheshe yalokhu.
I-Bluetooth SIG ayinaso isifaki khodi se-SBC njengelabhulali, futhi abakhiqizi basisebenzisa ngokwabo.
Lobu ubuthakathaka be-SBC - akukaze kucace kusengaphambili ukuthi iyiphi ikhwalithi yomsindo ongayilindela kusuka kudivayisi ethile. I-SBC ingakhiqiza umsindo wekhwalithi ephansi futhi ephezulu kakhulu, kodwa owakamuva awufinyeleleki ngaphandle kokukhubaza noma ukweqa imikhawulo yokwenziwa yezitaki ze-Bluetooth.

Isimo nge-AAC asicacile: ngakolunye uhlangothi, i-codec kufanele ikhiqize ikhwalithi engenakuhlukaniswa neyokuqala, kodwa ekusebenzeni, ukwahlulela ngokuhlolwa kwelebhu ye-SoundGuys kumadivayisi ahlukene we-Android, lokhu akuqinisekisiwe. Ngokunokwenzeka, iphutha likukubalula okulalelwayo kwehardware yekhwalithi ephansi eyakhelwe kuma-chipset efoni ahlukahlukene. Kunengqondo ukusebenzisa i-AAC kuphela kumadivayisi e-Apple, naku-Android ukuyikhawulela ku-aptX ne-LDAC.

Izingxenyekazi zekhompyutha ezisekela amanye amakhodekhi zivame ukuba ezekhwalithi ephezulu, ngenxa nje yokuthi kumadivayisi ashibhile kakhulu, asezingeni eliphansi, akuwenzi umqondo ukukhokha izindleko zelayisensi ukuze usebenzise lawo makhodekhi. Ekuhlolweni kwami, i-SBC izwakala iyinhle kakhulu kumishini yekhwalithi.

Ngenze isevisi yewebhu ehlanganisa umsindo ku-SBC, aptX kanye ne-aptX HD ngesikhathi sangempela, khona kanye esipheqululini. Ngayo, ungahlola lawa makhodekhi alalelwayo ngaphandle kokudlulisa umsindo nge-Bluetooth, kunoma imaphi ama-headphone anentambo, izipikha, nomculo owuthandayo, futhi ushintshe nemingcele yombhalo wekhodi ngokuqondile ngenkathi udlala umsindo:
btcodecs.valdikss.org.ru/sbc-encoder
Isevisi isebenzisa imitapo yolwazi ye-SBC evela kuphrojekthi ye-BlueZ kanye ne-libopenaptx evela ku-ffmpeg, ehlanganiswe yaba yi-WebAssembly ne-JavaScript esuka ku-C, nge-emscripten, ukuze iqalise esipheqululini. Ubani ongaphupha ngekusasa elinjalo!

Nakhu ukuthi kubukeka kanjani:

Qaphela ukuthi izinga lomsindo lishintsha kanjani ngemva kuka-20 kHz kumakhodekhi ahlukene. Ifayela lokuqala le-MP3 alinawo amaza angaphezu kuka-20 kHz.

Zama ukushintsha ama-codec futhi ubone ukuthi uyawuzwa yini umehluko phakathi kokwangempela, i-SBC 53 Joint Stereo (iphrofayela evamile nevame kakhulu), kanye ne-aptX/aptX HD.

Ngiyawuzwa umehluko phakathi kwamakhodekhi kumahedfoni!

Abantu abangawuzwa umehluko phakathi kwamakhodekhi ngesikhathi sokuhlolwa ngesevisi yewebhu bathi bayawuzwa lapho belalele umculo kuma-headphone angenantambo. Maye, lokhu akulona ihlaya noma umphumela we-placebo: umehluko uzwakala ngempela, kodwa awubangelwa umehluko. amakhodekhi.

Iningi lama-chipset alalelwayo e-Bluetooth asetshenziswa kumadivayisi amukela okungenantambo afakwe I-Digital Signal Processor (DSP), esebenzisa isilinganisi, i-compander, isisandisi se-stereo, nezinye izinto ezidizayinelwe ukuthuthukisa (noma ukushintsha) umsindo. Abakhiqizi bezinto ze-Bluetooth bangamisa i-DSP kukhodekhi ngayinye ngokwehlukana, futhi lapho ushintsha phakathi kwama-codec, umlaleli uzocabanga ukuthi uzwa umehluko ekusebenzeni kwama-codec, kuyilapho empeleni elalela izilungiselelo ezahlukene ze-DSP.

Ipayipi lokucubungula umsindo le-DSP Kalimba kuma-chip akhiqizwe yi-CSR/Qualcomm

Yenza kusebenze imisebenzi ehlukene ye-DSP yekhodekhi ngayinye kanye nokukhiphayo ngokwehlukana

Amanye amadivaysi e-premium eza nesofthiwe ekuvumela ukuthi wenze ngendlela oyifisayo izilungiselelo ze-DSP, kodwa ama-headphone ashibhile awakwenzi, futhi abasebenzisi abakwazi ukuvala ukucubungula komsindo mathupha.

Izici ezisebenzayo zamadivayisi

Inguqulo yesimanje ye-A2DP ejwayelekile ine Umsebenzi "wokulawula ivolumu ngokuphelele". — Ukulawulwa kwevolumu yedivayisi kusetshenziswa imiyalo ekhethekile yephrothokholi ye-AVRCP, elawula ukuzuzwa kwesiteji sokukhiphayo, esikhundleni sokunciphisa ngokuhlelekile ivolumu yomsindo womsindo. Uma uma ushintsha ivolumu kuma-headphone akho, ushintsho aluvumelani nevolumu yocingo lwakho, khona-ke ama-headphones akho noma ifoni ayisisekeli lesi sici. Kulokhu, kunengqondo ukulalela njalo umculo ngevolumu ephezulu ocingweni, ukulungisa ivolumu yangempela ngezinkinobho ze-headphone - kulokhu, isilinganiso sesignali-kuya-nomsindo sizoba ngcono kanye nekhwalithi yomsindo. kufanele ngaphezulu.
Eqinisweni, zikhona izimo ezidabukisayo. Kuma-headphone ami e-RealForce OverDrive D1 ye-SBC, i-compander eqinile iyavulwa, futhi ukukhulisa ivolumu kuholela ekwenyukeni kwezinga lemisindo ethule, kuyilapho ivolumu yemisindo ephezulu ingashintshi (isignali iyacindezelwa). Ngenxa yalokhu, kufanele usethe ivolumu kukhompyutha cishe isigamu, lapho kungenamphumela wokucindezela.
Ngokubona kwami, wonke ama-headphone anama-codec engeziwe asekela umsebenzi wokulawula ivolumu ngokuphelele, ngokusobala lokhu kungenye yezidingo zesitifiketi se-codec.

Amanye ama-headphone asekela ukuxhuma amadivaysi amabili ngesikhathi esisodwa. Lokhu kukuvumela, isibonelo, ukuthi ulalele umculo ophuma kukhompuyutha yakho futhi wamukele amakholi asuka ocingweni lwakho. Kodwa-ke, kufanele wazi ukuthi kule modi amanye ama-codec avaliwe futhi kusetshenziswa i-SBC kuphela.

I-AVDTP 1.3 Umsebenzi wokulibaziseka wokubika ivumela ama-headphones ukuthi akhulume ngokulibaziseka kudivayisi yokudlulisa lapho kudlalwa khona umsindo. Lokhu kukuvumela ukuthi ulungise ukuvumelanisa komsindo nevidiyo ngenkathi ubuka amafayela evidiyo: uma kunezinkinga ngokudluliswa komsakazo, umsindo ngeke usalele ngemuva kwevidiyo, kodwa ngokuphambene nalokho, ividiyo izokwehliswa isidlali sevidiyo kuze kube okulalelwayo nevidiyo kuyavunyelaniswa futhi.
Umsebenzi usekelwa ama-headphone amaningi, i-Android 9+ ne-Linux ene-PulseAudio 12.0+. Angazi ngosekelo lwalesi sici kwezinye izinkundla.

Ukuxhumana okubili nge-Bluetooth. Ukudluliswa kwezwi.

Ukuthumela ngezwi nge-Bluetooth, i-Synchronous Connection Oriented (SCO) isetshenziswa - ukudlulisa okuvumelanayo nokuxoxisana kokuqala koxhumano. Imodi ikuvumela ukuthi udlulise umsindo nezwi ngokulandelana ngokuqinile, ngesivinini sokuthumela nokwamukela esilinganayo, ngaphandle kokulinda ukuqinisekiswa kokudluliswa nokuthumela kabusha amaphakethe. Lokhu kunciphisa ukubambezeleka kukonke kokudluliswa komsindo esiteshini somsakazo, kodwa kubeka imingcele engathi sína enanini ledatha edluliswa ngeyunithi ngayinye yesikhathi, futhi kuthinte kabi ikhwalithi.
Uma le modi isetshenziswa, kokubili izwi nomsindo kudluliselwa ngekhwalithi efanayo.
Ngeshwa, kusukela ngo-2019, ikhwalithi yezwi phezu kwe-Bluetooth isempofu, futhi akucaci ukuthi kungani i-Bluetooth SIG ingenzi lutho ngakho.

I-CVSD

Ikhodekhi yenkulumo ye-CVSD eyisisekelo yenziwa yafana ngo-2002, futhi isekelwa yiwo wonke amadivaysi okuxhumana e-Bluetooth aqondiswa kabili. Ihlinzeka ngokudluliswa komsindo ngemvamisa yesampula engu-8 kHz, ehambisana nekhwalithi yocingo oluvamile lwezintambo.

Isibonelo sokurekhodwa kule codec.

mSBC

Ikhodekhi eyengeziwe ye-mSBC yenziwa yafana ngo-2009, futhi ngo-2010 ama-chips ayisebenzisela ukudluliswa kwezwi asevele avela. I-mSBC isekelwa kabanzi ngamadivayisi ahlukahlukene.
Lena akuyona i-codec ezimele, kodwa i-SBC evamile evela ezingeni le-A2DP, enephrofayili yombhalo wekhodi engaguquki: 16 kHz, mono, bitpool 26.

Isibonelo sokurekhodwa kule codec.

Ayihlakaniphile, kodwa ingcono kakhulu kune-CVSD, kodwa kusacasula ukuyisebenzisela ukuxhumana kwe-inthanethi, ikakhulukazi uma usebenzisa ama-headphone ukuxhumana nomdlalo - umsindo womdlalo uzosakazwa ngesilinganiso samasampula esingu-16 kHz.

Inkampani ye-FastStreamCSR yanquma ukuthuthukisa umbono wokusebenzisa i-SBC. Ukuze uzungeze imikhawulo yephrothokholi ye-SCO nokusebenzisa ama-bitrate aphezulu, i-CSR ihambe umzila ohlukile - bethula ukusekelwa komsindo we-SBC wezindlela ezimbili ku-A2DP ejwayelekile yokudlulisa umsindo yendlela eyodwa, amaphrofayili wombhalo wekhodi ajwayelekile, futhi bakubiza ngokuthi "FastStream".

I-FastStream idlulisela umsindo we-stereo ku-44.1 noma ku-48 kHz nge-bitrate engu-212 kbps kuzipikha, futhi i-mono, 16 kHz, ene-bitrate engu-72 kbps isetshenziselwa ukudlulisa umsindo kusuka kumakrofoni (ingcono kancane kune-mSBC). Imingcele enjalo ifaneleka kangcono ukuxhumana emidlalweni ye-intanethi - umsindo womdlalo kanye nabaxhumanisi bazoba sezingeni eliphezulu.

Isibonelo sokurekhodwa kule codec (+ umsindo ovela kumakrofoni, ofanayo ne-mSBC).

Le nkampani iqhamuke nenduku ethokozisayo, kodwa ngenxa yokuthi iphikisana nezinga le-A2DP, isekelwa kuphela kwamanye ama-transmitters enkampani (asebenza njengekhadi lomsindo le-USB, hhayi i-Bluetooth), kepha ayisebenzi. thola ukwesekwa ngezitaki ze-Bluetooth, nakuba inani lama-headphone anokusekelwa kwe-FastStream lingencane kangako.

Okwamanje, ukusekelwa kwe-FastStream ku-OS kuphela njengesichibi se-Linux PulseAudio kusukela kunjiniyela u-Pali Rohár, ongafakiwe egatsheni eliyinhloko lohlelo.

i-aptX Latency ephansi

Okumangazayo, i-aptX Low Latency iphinde isekele umsindo oqondiswa kabili, isebenzisa umgomo ofanayo ne-FastStream.
Akwenzeki ukusebenzisa lesi sici sekhodekhi noma yikuphi - akukho ukusekela kokukhishwa kwe-Low Latency kunoma iyiphi i-OS noma kunoma yisiphi isitaki se-Bluetooth esaziwa yimi.

I-Bluetooth 5, Amandla Akudala Naphansi

Kube nokudideka okuningi mayelana nokucaciswa kwe-Bluetooth nezinguqulo ngenxa yokuba khona kwezindinganiso ezimbili ezingahambelani ngaphansi komkhiqizo ofanayo, womabili asetshenziselwa kabanzi izinjongo ezihlukene.

Kunamaphrothokholi e-Bluetooth amabili ahlukene, angasebenzisani: I-Bluetooth Classic ne-Bluetooth Low Energy (LE, eyaziwa nangokuthi i-Bluetooth Smart). Kukhona nephrothokholi yesithathu, i-Bluetooth High Speed, kodwa ayisakazeki futhi ayisetshenziswa kumadivayisi asendlini.

Kusukela nge-Bluetooth 4.0, izinguquko ekucacisweni okuthintekayo ikakhulukazi i-Bluetooth Low Energy, kanye nenguqulo Yakudala ithole ukuthuthukiswa okuncane kuphela.

Uhlu lwezinguquko phakathi kwe-Bluetooth 4.2 ne-Bluetooth 5:

9 IZINGUQUKO KUSUKA KU-v4.2 UKUYA KU-5.0

9.1 IZICI EZINTSHA

Ziningana izici ezintsha ezethulwa ekukhishweni kwe-Bluetooth Core Specification 5.0. Izindawo eziyinhloko zokuthuthukiswa yilezi:
• Imaski yokutholakala kwesikhala (SAM)
• 2 Msym/s PHY we-LE
•LE Ububanzi Olude
• I-High Duty Cycle Ukukhangisa Okungaxhumeki
• Izandiso Zokukhangisa ze-LE
• I-Algorithm Yokukhetha Isiteshi #2
9.1.1 Izici Ezingezwe ku-CSA5 - Kuhlanganiswe ku-v5.0
•Amandla Okukhipha Aphezulu

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

Inguquko eyodwa kuphela ethinte inguqulo Yakudala ngaphakathi kohlaka lokucaciswa kwe-Bluetooth 5: bengeze usekelo lobuchwepheshe be-Slot Availability Mask (SAM), obuklanyelwe ukuthuthukisa ukuhlukaniswa komsakazo. Zonke ezinye izinguquko zithinta kuphela i-Bluetooth LE (kanye namandla okukhipha aphakeme kakhulu).

Zonke Amadivayisi omsindo asebenzisa i-Bluetooth Classic kuphela. Akunakwenzeka ukuxhuma ama-headphone nezikhulumi nge-Bluetooth Low Energy: ayikho indinganiso yokudlulisa umsindo usebenzisa i-LE. Izinga le-A2DP, elisetshenziselwa ukudlulisa umsindo wekhwalithi ephezulu, lisebenza kuphela nge-Bluetooth Classic, futhi ayikho i-analogue ku-LE.

Isiphetho - ukuthenga amadivaysi alalelwayo nge-Bluetooth 5 kuphela ngenxa yenguqulo entsha yephrothokholi akusizi ngalutho. I-Bluetooth 4.0/4.1/4.2 kumongo wokudlulisa umsindo izosebenza ngendlela efanayo.
Uma isimemezelo samahedfoni amasha sikhuluma ngebanga lokusebenza eliphindwe kabili kanye nokunciphisa ukusetshenziswa kwamandla ngenxa ye-Bluetooth 5, kufanele wazi ukuthi bona abaqondi noma bayakudukisa. Akumangalisi, ngoba ngisho nabakhiqizi be-Bluetooth chips ezimemezelweni zabo badidekile mayelana nomehluko phakathi kwenguqulo entsha yezinga, futhi amanye ama-Bluetooth 5 chips asekela inguqulo yesihlanu kuphela ye-LE, futhi asebenzise i-4.2 ye-Classic.

Ukubambezeleka kokudluliswa komsindo

Inani lokubambezeleka (ukubambezeleka) emsindweni lincike ezintweni eziningi: usayizi webhafa kusitaki somsindo, kusitaki se-Bluetooth nakudivayisi yokudlala okungenantambo ngokwayo, kanye nokulibaziseka kwe-algorithmic kwekhodekhi.

Ukubambezeleka kwama-codec alula njenge-SBC, i-aptX ne-aptX HD kuncane kakhulu, okungu-3-6 ms, okunganakwa, kodwa ama-codec ayinkimbinkimbi afana ne-AAC ne-LDAC angabangela ukuleleka okuphawulekayo. I-AAC algorithmic latency ye-44.1 kHz ingu-60 ms. I-LDAC - cishe 30 ms (ngokusekelwe ekuhlaziyeni okunzima kwekhodi yomthombo. Ngingaba nephutha, kodwa hhayi okuningi.)

Ukubambezeleka okuwumphumela kuncike kakhulu kudivayisi yokudlala, i-chipset yayo kanye nebhafa. Phakathi nokuhlolwa, ngithole ukusabalala kwe-150 kuya ku-250 ms kumadivayisi ahlukene (nge-codec ye-SBC). Uma sicabanga ukuthi amadivayisi asekela ama-codec engeziwe i-aptX, i-AAC ne-LDAC asebenzisa izingxenye zekhwalithi ephezulu kanye nosayizi omncane webhafa, sithola ukubambezeleka okujwayelekile okulandelayo:

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

Ake ngikukhumbuze: I-aptX Low Latency ayisekelwe ezinhlelweni zokusebenza, yingakho ukubambezeleka okuphansi kungatholwa kuphela ngesidlulisi+samukeli noma inhlanganisela ye-transmitter+headphone/isipika, futhi wonke amadivayisi kufanele asekele le codec.

Idivayisi ye-Bluetooth, izitifiketi, nezinkinga zelogo

Ungayihlukanisa kanjani idivayisi yomsindo yekhwalithi ephezulu kubuciko obushibhile? Ngokubukeka, okokuqala!

Ngamahedfoni e-Chinese ashibhile, izipikha kanye nabamukeli:

1. Igama elithi “Bluetooth” alikho ebhokisini kanye nedivayisi, “Wireless” kanye “BT” asetshenziswa kakhulu
2. Ilogo ye-Bluetooth ayikho ebhokisini noma kudivayisi
3. Ayikho i-LED ekhanyayo eluhlaza okwesibhakabhaka

Ukungabikho kwalezi zici kubonisa ukuthi idivayisi ayizange iqinisekiswe, okusho ukuthi inamandla ekhwalithi ephansi futhi iyinkinga. Isibonelo, ama-headphone e-Bluedio awaqinisekisiwe nge-Bluetooth futhi awahambisani ngokugcwele nokucaciswa kwe-A2DP. Bebengeke baphase izitifiketi.

Ake sicabangele amadivaysi amaningana namabhokisi avela kuwo:

Lawa wonke amadivayisi angaqinisekisiwe. Imiyalo ingase ibe nelogo kanye negama lobuchwepheshe be-Bluetooth, kodwa okubaluleke kakhulu ukuthi isebhokisini kanye/noma idivayisi ngokwayo.

Uma ama-headphone akho noma isipika sithi “Ze bluetooth dewise ixhunywe ngempumelelo”, lokhu nakho akubonisi ikhwalithi yazo:

isiphetho

Ingabe i-Bluetooth ingakwazi ukufaka esikhundleni ngokuphelele ama-headphone anentambo namahedisethi? Iyakwazi, kodwa ngezindleko zekhwalithi yocingo ephansi, ukubambezeleka okukhuphukile komsindo okungase kucasule emidlalweni, kanye nenqwaba yamakhodekhi aphathelene nokuphathelene adinga izimali zamalayisense futhi akhuphule izindleko zokugcina zakho kokubili ama-smartphone nama-headphone.

Ukumakethwa kwamanye ama-codec kunamandla kakhulu: i-aptX ne-LDAC zethulwa njengokushintshwa okulindelwe isikhathi eside kwe-SBC “ephelelwe yisikhathi nembi”, engeyimbi kangako njengoba abantu becabanga ukuthi injalo.

Njengoba kwenzeka, imikhawulo yokwenziwa yezitaki ze-Bluetooth ku-bitrate ye-SBC ingadlulwa, ukuze i-SBC ingabi ngaphansi kwe-aptX HD. Ngithathe isinyathelo ezandleni zami futhi ngenza isiqeshana se-LineageOS firmware: Silungisa isitaki se-Bluetooth ukuze sithuthukise umsindo kuma-headphone ngaphandle kwe-AAC, i-aptX ne-LDAC codec

Ulwazi olwengeziwe lungatholakala kumawebhusayithi Bafana bomsindo и I-SoundExpert.

Ibhonasi: Isifaki khodi se-SBC, ulwazi lwe-A2DP bitstream namafayela okuhlola. Leli fayela lalivame ukuthunyelwa esidlangalaleni kuwebhusayithi ye-Bluetooth, kodwa manje selitholakala kuphela kumalungu e-Bluetooth SIG.

Source: www.habr.com