Ngaphambi kokufunda eli nqaku, kucetyiswa ukuba ufunde inqaku elidlulileyo:
Abanye abasebenzisi bee-headphone ezingenazintambo babika umgangatho ophantsi wesandi kunye nokungabikho kwezandi eziphezulu xa usebenzisa i-codec eqhelekileyo ye-SBC yeBluetooth, exhaswa zizo zonke izixhobo zomsindo. Isincomo esiqhelekileyo sokuphucula isandi kukuthenga izixhobo kunye nee-headphone ezixhasa i-aptX kunye ne-LDAC codecs. Ezi codecs zifuna iintlawulo zelayisensi, ngoko ke izixhobo ezizixhasayo zibiza kakhulu.
Kuyavela ukuba umgangatho ophantsi we-SBC ubangelwa yimida yokwenziwa kwee-stacks zeBluetooth kunye noseto lwe-headphone, kwaye lo mda unokugqithiswa kuzo naziphi na izixhobo ezikhoyo ngotshintsho lwesoftware kwi-smartphone okanye kwikhompyuter.
Ikhowudi ye-SBC
I-codec ye-SBC ineeparamitha ezininzi ezahlukeneyo ekuxoxwa ngazo ngexesha lokuseta uqhagamshelo. Phakathi kwabo:
- Inombolo kunye nohlobo lwamajelo: I-Stereo edibeneyo, i-Stereo, i-Dual Channel, i-Mono;
- Inani leebhendi zokuphindaphinda: 4 okanye 8;
- Inani leebhloko kwiphakheji: 4, 8, 12, 16;
- I-algorithm yokusabalalisa amasuntswana ngexesha lokulinganisa: Umsindo, i-SNR;
- Ubuninzi kunye nexabiso elincinci le-pool ye-bits esetyenziswe ngexesha lokulinganisa (i-bitpool): ngokuqhelekileyo ukusuka kwi-2 ukuya kwi-53.
Isixhobo sokuguqula ikhowudi kufuneka sixhase nayiphi na indibaniselwano yezi parameters. Umfaki khowudi usenokungaphumezi yonke into.
Izitaki zeBluetooth ezikhoyo zivumelana ngokwesiqhelo kule profayile ilandelayo: I-Joint Stereo, iibhendi ezisi-8, iibhloko ezili-16, iLoudness, i-bitpool 2..53. Le profayile ifaka i-44.1 kHz yomsindo ngebitrate ye-328 kbps.
Ipharamitha ye-bitpool ichaphazela ngokuthe ngqo i-bitrate ngaphakathi kwiprofayili enye: iphezulu, iphezulu i-bitrate, kwaye ngoko umgangatho.
Nangona kunjalo, iparameter ye-bitpool ayibotshwanga kwiprofayili ethile; I-bitrate iphinda iphenjelelwe kakhulu zezinye iiparamitha: uhlobo lwetshaneli, inani leebhendi zamaza, inani leebhloko. Unokwandisa i-bitrate ngokungathanga ngqo, ngokuvuma kwiiprofayili ezingekho phantsi, ngaphandle kokutshintsha i-bitpool.
Ifomula yokubala ibitrate ye-SBC
Ngokomzekelo, i-Dual Channel mode idibanisa iziteshi ngokwahlukileyo, isebenzisa yonke i-bitpool yeshaneli nganye. Ngokunyanzela isixhobo ukuba sisebenzise iDual Channel endaweni ye-Joint Stereo, sifumana phantse kabini i-bitrate enexabiso elifanayo eliphezulu le-bitpool: 617 kbps.
Ngokombono wam, ukusetyenziswa kwexabiso le-bitpool elingaboshelwanga kwiprofayili kwinqanaba lothethathethwano liyimpazamo kumgangatho we-A2DP, obangele ukukhawulelwa kokwenziwa komgangatho we-SBC. Kuya kuba sengqiqweni ngakumbi ukuthethathethana nge-bitrate kune-bitpool.
Ezi xabiso zimiselweyo zeBitpool kunye neBitrate zivela kwitafile enamaxabiso acetyiswayo okusetyenziswa kwiaudio ekumgangatho ophezulu. Kodwa isincomo ayisosizathu sokuzikhawulela kwezi xabiso.
Ukucaciswa kwe-A2DP v1.2, ebisebenza ukusuka ngo-2007 ukuya ku-2015, ifuna zonke izixhobo zokuguqula iikhowudi zisebenze ngokuchanekileyo nge-bitrate ukuya kuthi ga kwi-512 kbps:
Idikhowuda ye-SNK iya kuxhasa onke amaxabiso e-bitpool anokubakho angaphumeleli ngaphezu kowona mlinganiselo mkhulu wesantya. Le inkangeleko inciphisa umlinganiselo webit okhoyo ukuya kwi-320kb/s ye-mono, kunye ne-512kb/s kwiimowudi zamatshaneli amabini.
Kwinguqulelo entsha yenkcazo akukho mda kwi-bitrate. Kuqikelelwa ukuba ii-headphones zanamhlanje ezikhutshwe emva kwe-2015 ezixhasa i-EDR zinokuxhasa amaxabiso amancinci ukuya kuthi ga kwi-β730 kbps.
Ngesizathu esithile, i-Linux (PulseAudio), i-Android, i-Blackberry kunye ne-macOS i-Bluetooth stacks endiyivavanyileyo inemida eyenziweyo kwixabiso eliphezulu le-bitpool parameter, echaphazela ngokuthe ngqo ubuninzi be-bitrate. Kodwa le ayisiyiyo ingxaki enkulu; phantse zonke ii-headphones zinciphisa ixabiso le-bitpool ephezulu ukuya kuma-53.
Njengoko sele ndibonile, uninzi lwezixhobo zisebenza ngokugqibeleleyo kwisitaki seBluetooth esilungisiweyo esine-bitrate ye-551 kbps, ngaphandle kokuphazamiseka okanye ukuqhekeka. Kodwa i-bitrate enjalo ayinakuze ihambelane phantsi kweemeko eziqhelekileyo, kwizitaki eziqhelekileyo zeBluetooth.
Ukulungisa istaki seBluetooth
Nayiphi na i-Bluetooth stack ehambelana nomgangatho we-A2DP inenkxaso ye-Dual Channel mode, kodwa akunakwenzeka ukuyivula kwi-interface.
Makhe songeze uguqulo kujongano! Ndenze iipetshi ze-Android 8.1 kunye ne-9 ye-Android ezongeza inkxaso epheleleyo yeSitishi esiMabini kwisitaki, yongeza imowudi kwimowudi yokuguqula imenyu kwizixhobo ze-dev, kwaye ndiphathe ii-SBCs ezinikwe i-Dual Channel-enabled ngokungathi ziyi-codec eyongezelelweyo njenge-aptX. , AAC, okanye LDAC ( Android ibiza le HD Audio) ngokongeza uphawu kwisethingi yesixhobo seBluetooth. Nantsi indlela ekhangeleka ngayo:
Xa ibhokisi yokukhangela ivuliwe, i-audio yeBluetooth iqala ukuhanjiswa nge-bitrate 551 kbps, ukuba ii-headphones zixhasa isantya soqhagamshelwano se-3 Mbit / s, okanye 452 kbps, ukuba ii-headphones zixhasa kuphela i-2 Mbit/s.
Esi siqwenga sibandakanyiwe kwezinye ii-firmwares zilandelayo:
- LineageOS
- Uvuko Remix
- crDroid
Ivela phi i-551 kunye ne-452 kbit/s?
Itekhnoloji yokwabelana ngomoya yeBluetooth yenzelwe ukuhambisa ngokufanelekileyo iipakethi ezinkulu ezinobungakanani obusisigxina. Ukudluliselwa kwedatha kwenzeka kwiindawo zokubeka, inani elikhulu lezithuba ezithunyelwa kwi-transfer enye yi-5. Kukho neendlela zokudlulisa ezisebenzisa i-1 okanye i-3 slots, kodwa kungekhona i-2 okanye i-4. Kwii-slots ezi-5 ungadlulisela ukuya kwi-679 bytes ngesantya soqhagamshelwano. of 2 Mbit / s kunye ukuya ku 1021 bytes ngesantya 3 Mbit / s, kunye 3 - 367 kunye 552 bytes, ngokulandelanayo.
Ukuba sifuna ukudlulisa idatha engaphantsi kwe-679 okanye i-1021 bytes, kodwa ngaphezu kwe-367 ββokanye i-552 bytes, ukudluliselwa kuya kusathatha i-5 slots kwaye idatha iya kudluliselwa ngexesha elifanayo, elinciphisa ukusebenza kakuhle kokudluliselwa.
I-SBC kwimodi ye-Dual Channel, kwi-44100 Hz yomsindo kunye ne-Bitpool 38 parameters, iibhloko ze-16 ngesakhelo ngasinye, i-8 frequency ranges, i-encodes audio kwi-164 byte frames, kunye ne-bitrate ye-452 kbps.
I-audio kufuneka ifakwe kwi-L2CAP kunye ne-AVDTP iiprothokholi zokudlulisa, ezithatha i-16 bytes ukusuka kumthwalo womsindo.
Ke, ukuhanjiswa kweBluetooth enye eneendawo zokubeka ezi-5 kunokwamkela iifreyimu zeaudio ezi-4:
679 (EDR 2 mbit/s DH5) - 4 (L2CAP) - 12 (AVDTP/RTP) - 1 (Π·Π°Π³ΠΎΠ»ΠΎΠ²ΠΎΠΊ SBC) - (164*4) = 6
Sifaka i-11.7 ms yedatha yomsindo kwipakethi ethunyelwayo, eya kuhanjiswa kwi-3.75 ms, kwaye sine-6 ββbytes engasetyenziswanga eseleyo kwipakethi.
Ukuba uphakamisa i-bitpool kancinane, akusayi kuphinda kube lula ukupakisha izakhelo ze-audio ezi-4 kwiphakheji enye. Kuya kufuneka uthumele iifreyimu ezi-3 ngexesha, nto leyo enciphisa ukusebenza kakuhle kosasazo, inciphisa ubungakanani besandi esisasazwa ngesakhelo ngasinye, kwaye iya kukhokelela ngokukhawuleza ekuthinintithekeni kweaudio kwiimeko ezimbi zikanomathotholo.
Ngendlela efanayo, i-bitrate ye-551 kbit / s ikhethwe kwi-EDR 3 Mbit / s: kunye ne-Bitpool 47, iibhloko ze-16 ngesakhelo, i-8 frequency ranges, ubukhulu besakhelo ngama-bytes angama-200, kunye ne-bitrate ye-551 kbit / s. Iphakheji enye iqulethe iifreyimu ezi-5 okanye i-14.6 ms yomculo.
I-algorithm yokubala zonke iiparamitha ze-SBC intsonkothile, unokubhideka ngokulula ukuba ubala ngesandla, ke ndenze isixhobo sokubala esisebenzisanayo ukunceda abo banomdla:
Kutheni kufuneka konke oku?
Ngokuchasene nenkolelo ethandwayo malunga nomgangatho ovakalayo we-aptX codec, kwezinye iifayile inokuvelisa iziphumo ezimbi kune-SBC kunye ne-bitrate eqhelekileyo ye-328 kbps.
I-SBC inikezela ngokuguquguqukayo amasuntswana obungakanani kwiibhendi zefrikhwensi kwisiseko esisezantsi ukuya phezulu. Ukuba yonke ibitrate ibisetyenziselwe amaza aphantsi kunye namaza aphakathi, iifrikhwensi eziphezulu ziya βkunqunyulwaβ (kuya kubakho ukuthula endaweni yoko).
I-aptX yenza ubungakanani beebhendi zefrikhwensi ngenani elifanayo lebits ngamaxesha onke, yiyo loo nto ine-bitrate engaguqukiyo: 352 kbps ye-44.1 kHz, 384 kbps ye-48 kHz, kwaye ayikwazi "i-bit-shift" kwezo frikhwensi ziwadinga kakhulu. . Ngokungafaniyo ne-SBC, i-aptX ayizu βkusikaβ iifrikhwensi, kodwa iyakongeza ingxolo yokulinganisa kubo, inciphisa uluhlu oluguquguqukayo lweaudio, kwaye ngamanye amaxesha yazisa ukuqhekeka kweempawu. I-SBC "itya iinkcukacha" - ilahla ezona ndawo zithuleyo.
Ngokomyinge, xa kuthelekiswa ne-SBC 328k, i-aptX yazisa ukugqwetheka okuncinci kumculo onoluhlu olubanzi lwamafrikhwensi, kodwa kumculo onoluhlu oluncinci lwamaza kunye noluhlu olubanzi, i-SBC 328k ngamanye amaxesha iyaphumelela.
Makhe siqwalasele imeko ekhethekileyo. ISpectrogram yepiyano edlala ukurekhoda:
Amandla aphambili ahlala kwii-frequencies ukusuka kwi-0 ukuya kwi-4 kHz, kwaye iyaqhubeka ukuya kwi-10 kHz.
I-spectrogram yefayile ecinezelwe kwi-aptX ibonakala ngolu hlobo:
Kwaye yile nto ibonakala ngathi i-SBC 328k.
Inokubonwa ukuba i-SBC 328k yacima ngamaxesha athile ngokupheleleyo uluhlu olungaphezulu kwe-16 kHz, kwaye ichithe yonke ibitrate ekhoyo kuluhlu olungaphantsi kweli xabiso. Nangona kunjalo, i-aptX yazisa ngakumbi ukugqwetheka kwi-spectrum yefrikhwensi evakalayo kwindlebe yomntu, njengoko kunokubonwa kwi-spectrogram yoqobo ethatyathiweyo ukusuka kwi-aptX spectrogram (eqaqambileyo, ngakumbi ukugqwetheka):
Ngelixa i-SBC 328k yonakalise isignali encinci kuluhlu ukusuka kwi-0 ukuya kwi-10 kHz, kwaye yasika enye:
I-485k bitrate ye-SBC yayanele ukugcina lonke uluhlu lwamaza, ngaphandle kokuvala iibhendi.
I-SBC 485k iphambili kakhulu kwi-aptX kule ngoma kuluhlu lwe-0-15 kHz, kunye nomahluko omncinci, kodwa obonakalayo - kwi-15-22 kHz (ubumnyama, ukugqwesa okuncinci):
.
Ngokutshintshela kwi-Bitrate ephezulu ye-SBC, uya kufumana i-audio ehlala ibetha i-aptX kuyo nayiphi na i-headphone. Kwii-headphones ezixhasa uqhagamshelwano lwe-3 Mbps EDR, i-bitrate ye-551 kbps ivelisa isandi esifaniswa ne-aptX HD.
Ngaba ungenza ngakumbi?
Isiqwenga se-Android sikwabandakanya ukhetho lokunyusa ngakumbi i-bitrate yezixhobo ze-2 Mbps EDR. Unokwandisa i-bitrate ukusuka kwi-452 kbit/s ukuya kwi-595 kbit/s, ngexabiso lokunciphisa uzinzo losasazo kwiimeko ezinzima zerediyo.
Kwanele ukuseta i-persist.bluetooth.sbc_hd_higher_bitrate eguquguqukayo ukuya ku-1:
# setprop persist.bluetooth.sbc_hd_higher_bitrate 1I-bitrate patch egqithisileyo ukuza kuthi ga ngoku yamkelwe kuphela kwi-LineageOS 15.1, kodwa hayi kwi-16.0.
Ukuhambelana kwesixhobo
I-SBC Dual Channel ixhaswa phantse zonke ii-headphones, izithethi kunye neeyunithi zentloko yemoto. Oku akumangalisi - umgangatho ufuna inkxaso yawo kuzo naziphi na izixhobo zokuguqula iikhowudi. Kukho inani elincinci lezixhobo apho le modi ibangela iingxaki, kodwa ezi ziimeko ezizimeleyo.
Iinkcukacha ezithe vetshe malunga nezixhobo ezihambelanayo zinokufumaneka apha okanye .
Ukuthelekiswa kwezandi ezahlukeneyo
Ndenze inkonzo yewebhu efaka i-audio kwi-SBC (kunye ne-aptX kunye ne-aptX HD) ngexesha lokwenyani, kanye kwisikhangeli. Ngayo, unokuthelekisa isandi seeprofayili ze-SBC ezahlukeneyo kunye nezinye ii-codecs, ngaphandle kokuhambisa iaudio ngeBluetooth, nakweyiphi na i-headphones eneentambo, izithethi, kunye nomculo owuthandayo, kwaye utshintshe iiparameters ze-encoding ngokuthe ngqo ngelixa udlala umsindo.
Qhagamshelana nabaPhuhlisi be-Android
Ndabhalela abaninzi abaphuhlisi be-stack beBluetooth kuGoogle ndibacela ukuba baqwalasele ukubandakanya iipetshi kwisebe eliphambili le-Android - i-AOSP, kodwa abazange bafumane impendulo enye. Iziqwenga zam zingene naye wahlala ngaphandle kokuphawula kuye nabani na obandakanyekayo.
Ndingavuya ukuba ndingafumana uncedo ekunxibelelaneni nabaphuhlisi kuGoogle kwaye ndizise i-SBC HD kwi-Android. Isiqwenga kwi-gerrit sele siphelelwe lixesha (le yenye yohlaziyo lokuqala), kwaye ndiza kuyihlaziya ukuba abaphuhlisi banomdla kwiinguqu zam (akulula kum ukuyihlaziya, andinazo izixhobo ezihambelana ne-Android Q. ).
isiphelo
Abasebenzisi bee-smartphones ezine-LineageOS, iResurrection Remix kunye ne-crDroid firmware banokonwabela umgangatho ophuculweyo wesandi ngoku, vula nje ukhetho kuseto lwesixhobo seBluetooth. Abasebenzisi beLinux banokufumana ukonyuka kwe-bitrate ye-SBC ngokufaka , leyo, phakathi kwezinye izinto, yongeza inkxaso ye-aptX, i-aptX HD kunye ne-FastStream codecs.
umthombo: www.habr.com