Ngaphambi kokufunda lesi sihloko, kunconywa ukuthi ufunde isihloko esandulele:
Abanye abasebenzisi bama-headphone angenantambo babika ikhwalithi yomsindo ephansi kanye nokuntuleka kwamafrikhwensi aphezulu uma usebenzisa i-codec ye-Bluetooth ye-SBC ejwayelekile, esekelwa yiwo wonke amadivayisi omsindo. Isincomo esivamile sokuthuthukisa umsindo ukuthenga amadivayisi nama-headphone asekela i-aptX ne-LDAC codec. Lawa makhodekhi adinga izinkokhelo zamalayisense, ngakho amadivayisi awasekelayo abiza kakhulu.
Kuvele ukuthi ikhwalithi ephansi ye-SBC ingenxa yemikhawulo yokwenziwa yezitaki ze-Bluetooth nezilungiselelo zamahedfoni, futhi lo mkhawulo ungadlula kunoma imaphi amadivaysi akhona ngokushintsha kwesoftware ku-smartphone noma ikhompuyutha.
I-Codec SBC
Ikhodekhi ye-SBC inamapharamitha amaningi ahlukene okuxoxiswane ngawo phakathi nesigaba sokusetha uxhumano. Phakathi kwazo:
- Inombolo nohlobo lwamashaneli: I-Joint Stereo, i-Stereo, i-Dual Channel, i-Mono;
- Inombolo yamabhendi okuvama: 4 noma 8;
- Inombolo yamabhuloki ephaketheni: 4, 8, 12, 16;
- I-algorithm yokusabalalisa izingcezu ngesikhathi sokulinganisa: Umsindo, i-SNR;
- Inani eliphakeme nelincane lephuli yamabhithi asetshenziswa ngesikhathi sokulinganisa (i-bitpool): ngokuvamile ukusuka ku-2 ukuya ku-53.
Idivayisi yokukhipha amakhodi kufanele isekele noma iyiphi inhlanganisela yale mingcele. Isishumeki singase singasebenzisi yonke into.
Izitaki ze-Bluetooth ezikhona ngokuvamile zivumelana ngale phrofayela elandelayo: I-Joint Stereo, amabhendi angu-8, amabhlogo angu-16, Umsindo omkhulu, i-bitpool 2..53. Le phrofayela ifaka umsindo ongu-44.1 kHz nge-bitrate engu-328 kbps.
Ipharamitha ye-bitpool ithinta ngokuqondile i-bitrate ngaphakathi kwephrofayela eyodwa: uma iphezulu, i-bitrate ephezulu, ngakho-ke ikhwalithi.
Noma kunjalo, ipharamitha ye-bitpool ayiboshiwe kuphrofayela ethile; I-bitrate iphinde ithonywe kakhulu amanye amapharamitha: uhlobo lwamashaneli, inani lamabhendi amafrikhwensi, inani lamabhulokhi. Ungakwazi ukwandisa i-bitrate ngokungaqondile, ngokuvumelana namaphrofayili angewona ajwayelekile, ngaphandle kokushintsha i-bitpool.
Ifomula yokubala i-bitrate ye-SBC
Isibonelo, Imodi Yeziteshi Ezikabili ihlanganisa iziteshi ngokuhlukana, isebenzisa yonke i-bitpool yesiteshi ngasinye. Ngokuphoqa idivayisi ukuthi isebenzise I-Dual Channel esikhundleni se-Joint Stereo, sithola cishe kabili i-bitrate enenani eliphezulu elifanayo le-bitpool: 617 kbps.
Ngokubona kwami, ukusetshenziswa kwenani le-bitpool elingaboshelwanga kuphrofayela esigabeni sokuxoxisana kuyiphutha esilinganisweni se-A2DP, okuholele ekukhawulweni kokwenziwa kwekhwalithi ye-SBC. Kungaba nengqondo ukuxoxisana nge-bitrate kune-bitpool.
Lawa manani angaguquki e-Bitpool ne-Bitrate asuka kuthebula elinamanani anconyiwe ukuze asetshenziselwe umsindo wekhwalithi ephezulu. Kodwa isincomo akusona isizathu sokuzikhawulela kulawa magugu.
Ukucaciswa kwe-A2DP v1.2, obekusebenza kusuka ngo-2007 kuya ku-2015, kudinga ukuthi zonke izisetshenziswa zokukhipha amakhodi zisebenze kahle ngama-bitrate afika ku-512 kbps:
Idekhoda ye-SNK izosekela wonke amanani e-bitpool angaba khona angaphumeleli eqinisweni lesilinganiso sebhithi esiphezulu. Le phrofayela ikhawulela isilinganiso sebhithi esiphezulu esitholakalayo sibe ngu-320kb/s ku-mono, kanye no-512kb/s kumamodi eziteshi ezimbili.
Enguqulweni entsha yokucaciswa akukho mkhawulo ku-bitrate. Kulinganiselwa ukuthi ama-headphone esimanje akhululwe ngemva kuka-2015 asekela i-EDR angasekela ama-bit rates afika ku-β730 kbps.
Ngesizathu esithile, izitaki ze-Linux (PulseAudio), Android, Blackberry kanye ne-macOS Bluetooth engizihlolile zinemikhawulo yokwenziwa enanini eliphakeme lepharamitha ye-bitpool, ethinta ngokuqondile umkhawulo we-bitrate. Kodwa lena akuyona inkinga enkulu kakhulu; cishe wonke ama-headphone abuye akhawulele inani eliphakeme le-bitpool ku-53.
Njengoba sengibonile, iningi lamadivayisi lisebenza kahle kusitaki se-Bluetooth esilungisiwe esine-bitrate engu-551 kbps, ngaphandle kokuphazamiseka noma ukuqhekeka. Kodwa i-bitrate enjalo ngeke ize ihambisane ngaphansi kwezimo ezijwayelekile, kuzitaki ezijwayelekile ze-Bluetooth.
Ukulungisa isitaki se-Bluetooth
Noma yisiphi isitaki se-Bluetooth esihambisana nezinga le-A2DP sinokusekelwa kwemodi Yeziteshi Ezikabili, kodwa akwenzeki ukusivula esixhumi esibonakalayo.
Ake sengeze ukuguqula kusixhumi esibonakalayo! Ngenze iziqephu ze-Android 8.1 ne-Android 9 ezengeza ukusekelwa okugcwele kwe-Dual Channel kusitaki, engeza imodi kumodi yokuguqula imenyu kumathuluzi e-dev, futhi ngiphathe ama-SBC anikwe amandla i-Dual Channel njengokungathi ayikhodekhi eyengeziwe njenge-aptX. , AAC, noma i-LDAC ( I-Android ibiza le HD Audio) ngokwengeza uphawu lokuhlola kuzilungiselelo zedivayisi ye-Bluetooth. Nansi indlela ebukeka ngayo:
Uma ibhokisi lokuhlola lenziwe lasebenza, umsindo we-Bluetooth uqala ukudluliselwa nge-bitrate 551 kbps, uma ama-headphone asekela isivinini sokuxhuma esingu-3 Mbit/s, noma 452 kbps, uma ama-headphone asekela i-2 Mbit/s kuphela.
Lesi siqeshana sifakiwe kwamanye ama-firmware alandelayo:
- LineageOS
- Ukuvuselela Remix
- crDroid
Avelaphi ama-551 kanye nama-452 kbit/s?
Ubuchwepheshe bokwabelana komoya be-Bluetooth buklanyelwe ukudlulisa ngempumelelo amaphakethe amakhulu anosayizi ongashintshi. Ukudluliswa kwedatha kwenzeka ezikhaleni, inombolo enkulu yezikhala ezithunyelwe ngokudluliswa okukodwa ngu-5. Kukhona futhi izindlela zokudlulisa ezisebenzisa izikhala ezi-1 noma ezi-3, kodwa hhayi ezi-2 noma ezi-4. Ezikhaleni ezingu-5 ungadlulisela kufika ku-679 bytes ngesivinini sokuxhuma. ka-2 Mbit/s futhi kufika ku-1021 byte ngesivinini esingu-3 Mbit/s, futhi ku-3 - 367 no-552 bytes, ngokulandelana.
Uma sifuna ukudlulisa idatha encane kunamabhayithi angu-679 noma angu-1021, kodwa ngaphezu kwamabhayithi angu-367 noma angu-552, ukudluliswa kusazothatha izikhala ezi-5 futhi idatha izodluliswa ngesikhathi esifanayo, okunciphisa ukusebenza kahle kokudlulisa.
I-SBC kumodi ye-Dual Channel, kumsindo ongu-44100 Hz namapharamitha we-Bitpool 38, amabhulokhi angu-16 kuhlaka ngalunye, izigaba zokuvama eziyi-8, ifaka umsindo kumafreyimu angama-164 byte, nge-bitrate engu-452 kbps.
Umsindo kufanele uhlanganiswe ku-L2CAP kanye ne-AVDTP yezivumelwano zokudlulisa, ezithatha amabhayithi angu-16 ekulayisheni okulalelwayo.
Ngakho-ke, ukudluliswa kwe-Bluetooth okukodwa okunama-slots angu-5 kungakwazi ukufaka amafreyimu omsindo angu-4:
679 (EDR 2 mbit/s DH5) - 4 (L2CAP) - 12 (AVDTP/RTP) - 1 (Π·Π°Π³ΠΎΠ»ΠΎΠ²ΠΎΠΊ SBC) - (164*4) = 6
Sifaka u-11.7 ms wedatha yomsindo ephaketheni elithunyelwayo, elizodluliselwa ngo-3.75 ms, futhi sisele namabhayithi angu-6 angasetshenzisiwe ephaketheni.
Uma uphakamisa i-bitpool kancane, ngeke kusakwazi ukupakisha amafreyimu omsindo angu-4 kuphakheji eyodwa. Kuzodingeka ukuthi uthumele amafreyimu angu-3 ngesikhathi, okunciphisa ukusebenza kahle kokudlulisela, kunciphisa inani lomsindo odluliswayo ngokuthumela ngakunye, futhi kuzoholela ngokushesha ekungingizani komsindo ezimweni ezimbi zomsakazo.
Ngendlela efanayo, i-bitrate engu-551 kbit/s ikhethelwe i-EDR 3 Mbit/s: ene-Bitpool 47, amabhulokhi angu-16 uzimele ngamunye, ububanzi befrikhwensi angu-8, usayizi wozimele ungamabhayithi angu-200, ne-bitrate engu-551 kbit/s. Iphakheji elilodwa liqukethe amafreyimu angu-5 noma 14.6 ms omculo.
I-algorithm yokubala yonke imingcele ye-SBC iyinkimbinkimbi impela, ungadideka kalula uma ubala mathupha, ngakho ngenze isibali esisebenzisanayo ukusiza labo abathanda:
Kungani kudingeka konke lokhu?
Ngokuphambene nenkolelo evamile mayelana nekhwalithi yomsindo ye-aptX codec, kwamanye amafayela ingaveza imiphumela emibi kune-SBC ene-bitrate evamile engu-328 kbps.
I-SBC inika amandla amabhithi wokulinganisa kumabhendi wefrikhwensi ngokwesisekelo esiphansi ukuya phezulu. Uma yonke i-bitrate isetshenziswe kumafrikhwensi aphansi naphakathi, amaza aphezulu "azonqunywa" (kuyoba nokuthula esikhundleni salokho).
I-aptX ilinganisa amabhendi efrikhwensi ngenani elifanayo lamabhithi ngaso sonke isikhathi, yingakho ine-bitrate engaguquki: 352 kbps ye-44.1 kHz, 384 kbps ngo-48 kHz, futhi ayikwazi "ukushintsha kancane" kulawo mafrikhwensi awadinga kakhulu. . Ngokungafani ne-SBC, i-aptX ngeke βisikeβ amaza, kodwa izongeza umsindo wokulinganisa kuwo, inciphise ububanzi obuguquguqukayo bomsindo, futhi ngezinye izikhathi yethule ukuqhekeka kwesici. I-SBC "idla imininingwane" - ilahla izindawo ezithule kakhulu.
Ngokwesilinganiso, uma kuqhathaniswa ne-SBC 328k, i-aptX yethula ukuhlanekezela okuncane emculweni onobubanzi befrikhwensi, kodwa emculweni onobubanzi obuncane befrikhwensi nobubanzi obuguquguqukayo, i-SBC 328k kwesinye isikhathi iyawina.
Ake sicabangele icala elikhethekile. I-Spectrogram yokuqoshwa kwepiyano edlalayo:
Amandla amakhulu atholakala kumafrikhwensi asuka ku-0 kuye ku-4 kHz, futhi aqhubeka aze afike ku-10 kHz.
I-spectrogram yefayela elicindezelwe ku-aptX ibonakala kanje:
Futhi yile ndlela i-SBC 328k ebukeka ngayo.
Kuyabonakala ukuthi i-SBC 328k ivamise ukucisha ngokuphelele ububanzi obungaphezulu kuka-16 kHz, futhi yachitha yonke i-bitrate etholakalayo kububanzi obungaphansi kwaleli nani. Kodwa-ke, i-aptX yethule ukuhlanekezela okwengeziwe ku-spectrum yefrikhwensi ezwakala endlebeni yomuntu, njengoba kungabonwa ku-spectrogram yasekuqaleni ekhishiwe ku-aptX spectrogram (ekhanya kakhulu, ihlanekezela kakhulu):
Ngenkathi i-SBC 328k yonakalise isignali kancane ebangeni ukusuka ku-0 kuye ku-10 kHz, futhi yanqamula okunye:
I-bitrate engu-485k ye-SBC yayanele ukugcina lonke ibanga lefrikhwensi, ngaphandle kokukhubaza amabhendi.
I-SBC 485k iphambili kakhulu kune-aptX kule threkhi ebangeni elingu-0-15 kHz, inomehluko omncane kodwa osabonakala ongu-15-22 kHz (okuyoba mnyama ukuhlanekezela okuncane):
.
Ngokushintshela ku-SBC ene-bitrate ephezulu, uzothola umsindo ovame ukuhlula i-aptX kunoma iyiphi i-headphone. Kuma-headphone asekela uxhumano lwe-3 Mbps EDR, i-bitrate engu-551 kbps ikhiqiza umsindo ofana ne-aptX HD.
Ungakwazi yini ukwenza okwengeziwe?
Isiqeshana se-Android sihlanganisa nenketho yokwandisa i-bitrate kumadivayisi angu-2 Mbps EDR. Ungakwazi ukukhulisa i-bitrate isuke ku-452 kbit/s iye ku-595 kbit/s, ngezindleko zokunciphisa ukuzinza kokudlulisela ezimweni ezinzima zomsakazo.
Kwanele ukusetha okuguquguqukayo kwe-persist.bluetooth.sbc_hd_higher_bitrate ukuze kube ngu-1:
# setprop persist.bluetooth.sbc_hd_higher_bitrate 1I-bitrate patch eyedlulele kuze kube manje yamukelwe kuphela ku-LineageOS 15.1, kodwa hhayi ku-16.0.
Ukuhambisana Kwedivayisi
I-SBC Dual Channel isekelwa cishe yiwo wonke ama-headphone, izipikha namayunithi ekhanda lemoto. Lokhu akumangalisi - izinga lidinga ukwesekwa kwalo kunoma imaphi amadivaysi okukhipha amakhodi. Kunenombolo encane yamadivayisi lapho le modi idala izinkinga, kodwa lezi yizimo ezingazodwa.
Imininingwane eyengeziwe mayelana namadivayisi ahambisanayo ingatholakala kokuthi noma .
Ukuqhathanisa umehluko wemisindo
Ngenze isevisi yewebhu ehlanganisa umsindo ku-SBC (kanye ne-aptX ne-aptX HD) ngesikhathi sangempela, khona kanye esipheqululini. Ngayo, ungaqhathanisa umsindo wamaphrofayili e-SBC ahlukene namanye ama-codec, ngaphandle kokudlulisa umsindo nge-Bluetooth, kunoma imaphi ama-headphone anentambo, izipikha, nomculo wakho owuthandayo, futhi ushintshe nemingcele yombhalo wekhodi ngokuqondile ngenkathi udlala umsindo.
Xhumana Nonjiniyela be-Android
Ngibhalele abathuthukisi besitaki be-Bluetooth abaningi kwa-Google ngibacela ukuthi bacabangele ukufaka amapheshana egatsheni eliyinhloko le-Android - i-AOSP, kodwa abatholanga impendulo eyodwa. Iziqephu zami zingenile futhi uhlale ngaphandle kokuphawula kunoma ubani ohilelekile.
Ngingajabula uma ngingathola usizo lokuxhumana nonjiniyela bakwa-Google nokuletha i-SBC HD ku-Android. I-patch in gerrit isiphelelwe yisikhathi (lokhu kungenye yezibuyekezo zakuqala), futhi ngizoyibuyekeza uma abathuthukisi bethanda izinguquko zami (akulula kimi ukuyibuyekeza, anginawo amadivayisi ahambisana ne-Android Q ).
isiphetho
Abasebenzisi bama-smartphone ane-LineageOS, i-Resurrection Remix ne-crDroid firmware bangajabulela ikhwalithi yomsindo ethuthukisiwe njengamanje, vele wenze kusebenze inketho kuzilungiselelo zedivayisi ye-Bluetooth. Abasebenzisi be-Linux bangathola futhi i-bitrate ye-SBC eyengeziwe ngokufaka , okuthi, phakathi kwezinye izinto, ingeze ukusekelwa kwe-aptX, i-aptX HD namakhodi e-FastStream.
Source: www.habr.com