Ua ntej nyeem tsab xov xwm no, nws raug nquahu kom koj nyeem tsab xov xwm dhau los:
Qee cov neeg siv lub mloog pob ntseg wireless qhia txog lub suab tsis zoo thiab tsis muaj lub suab nrov thaum siv tus qauv SBC Bluetooth codec, uas tau txais kev txhawb nqa los ntawm txhua lub suab. Ib qho lus pom zoo rau kev txhim kho lub suab yog yuav khoom siv thiab lub mloog pob ntseg uas txhawb nqa aptX thiab LDAC codecs. Cov codecs no xav tau cov nqi ntawv tso cai, yog li cov khoom siv uas txhawb nqa lawv kim dua.
Nws hloov tawm tias qhov tsis zoo ntawm SBC yog vim muaj kev txwv tsis pub muaj kev txwv ntawm Bluetooth pawg thiab lub mloog pob ntseg teeb tsa, thiab qhov kev txwv no tuaj yeem hla ntawm txhua yam khoom siv uas twb muaj lawm los ntawm kev hloov pauv software rau lub xov tooj smartphone lossis khoos phis tawj.
Codec SBC
SBC codec muaj ntau qhov sib txawv uas tau sib tham thaum lub sijhawm teeb tsa kev sib txuas. Ntawm lawv:
- Tus naj npawb thiab hom channel: Joint Stereo, Stereo, Dual Channel, Mono;
- Tus naj npawb ntawm zaus: 4 lossis 8;
- Tus naj npawb ntawm cov blocks hauv pob: 4, 8, 12, 16;
- Algorithm rau faib cov khoom thaum lub sij hawm quantization: Suab nrov, SNR;
- Qhov siab tshaj plaws thiab yam tsawg kawg nkaus tus nqi ntawm lub pas dej ntawm cov khoom siv thaum lub sij hawm quantization (bitpool): feem ntau yog los ntawm 2 mus rau 53.
Cov cuab yeej txiav txim siab yuav tsum txhawb nqa txhua qhov sib xyaw ua ke ntawm cov kev txwv no. Tus encoder yuav tsis siv txhua yam.
Cov pob Bluetooth uas twb muaj lawm feem ntau pom zoo rau ntawm qhov profile hauv qab no: Joint Stereo, 8 bands, 16 blocks, Suab nrov, bitpool 2..53. Qhov profile no encodes 44.1 kHz suab ntawm bitrate ntawm 328 kbps.
Lub bitpool parameter ncaj qha cuam tshuam cov bitrate hauv ib qhov profile: qhov siab dua nws yog, qhov siab dua qhov bitrate, thiab yog li qhov zoo.
Txawm li cas los xij, lub bitpool parameter tsis khi rau ib qho profile tshwj xeeb; Tus bitrate kuj tseem cuam tshuam los ntawm lwm yam tsis muaj: hom channels, tus naj npawb ntawm zaus bands, tus naj npawb ntawm cov blocks. Koj tuaj yeem nce tus bitrate indirect, los ntawm kev pom zoo rau cov tsis-tus qauv profiles, tsis tas yuav hloov lub bitpool.
Formula rau xam SBC bitrate
Piv txwv li, Dual Channel hom encodes channel cais, siv tag nrho cov bitpool rau txhua channel. Los ntawm kev yuam kom lub cuab yeej siv Dual Channel tsis yog Joint Stereo, peb tau yuav luag ob npaug ntawm tus nqi qis nrog tib tus nqi siab tshaj plaws bitpool: 617 kbps.
Hauv kuv lub tswv yim, kev siv tus nqi bitpool tsis khi rau ib qho profile ntawm kev sib tham theem yog qhov tsis txaus ntseeg hauv A2DP tus qauv, uas ua rau muaj kev txwv tsis pub muaj SBC zoo. Nws yuav ua rau muaj kev nkag siab ntau dua rau kev sib tham bitrate es tsis yog bitpool.
Cov kev ruaj ntseg Bitpool thiab Bitrate qhov tseem ceeb no pib los ntawm lub rooj nrog cov lus pom zoo rau kev siv rau lub suab zoo. Tab sis qhov kev pom zoo tsis yog vim li cas los txwv koj tus kheej rau cov txiaj ntsig no.
A2DP v1.2 specification, uas tau ua haujlwm los ntawm 2007 txog 2015, xav kom txhua tus lej txiav txim siab ua haujlwm kom raug nrog bitrates txog 512 kbps:
Tus decoder ntawm SNK yuav tsum txhawb nqa tag nrho cov txiaj ntsig bitpool uas tsis ua rau ntau dhau ntawm qhov siab tshaj plaws me ntsis. Qhov profile no txwv qhov muaj peev xwm siab tshaj plaws rau 320kb / s rau mono, thiab 512kb / s rau ob-channel hom.
Nyob rau hauv lub tshiab version ntawm lub specification tsis muaj kev txwv ntawm tus bitrate. Nws kwv yees tias lub mloog pob ntseg niaj hnub tso tawm tom qab xyoo 2015 uas txhawb EDR tuaj yeem txhawb nqa tus nqi me ntsis txog β730 kbps.
Rau qee qhov laj thawj, Linux (PulseAudio), Android, Blackberry thiab macOS Bluetooth pawg kuv tau sim muaj cov kev txwv tsis pub tshaj ntawm tus nqi siab tshaj plaws ntawm bitpool parameter, uas cuam tshuam ncaj qha rau qhov siab tshaj plaws bitrate. Tab sis qhov no tsis yog qhov teeb meem loj tshaj plaws; yuav luag txhua lub mloog pob ntseg kuj txwv qhov siab tshaj plaws bitpool tus nqi rau 53.
Raws li kuv tau pom lawm, cov khoom siv feem ntau ua haujlwm zoo kawg nkaus ntawm kev hloov kho Bluetooth pawg nrog tus nqi qis ntawm 551 kbps, tsis muaj kev cuam tshuam lossis tawg. Tab sis xws li ib tug bitrate yuav tsis zoo ib yam nyob rau hauv ib txwm tej yam kev mob, ntawm ib txwm Bluetooth pawg.
Hloov kho cov pawg Bluetooth
Txhua pawg Bluetooth uas tau sib xws nrog A2DP tus qauv muaj kev txhawb nqa rau Dual Channel hom, tab sis nws tsis tuaj yeem qhib nws los ntawm lub interface.
Cia peb ntxiv lub toggle rau lub interface! Kuv tau ua thaj ua rau thaj rau Android 8.1 thiab Android 9 uas ntxiv tag nrho Dual Channel txhawb nqa rau pawg, ntxiv ib hom rau hom toggle zaub mov hauv cov cuab yeej dev, thiab kho Dual Channel-enabled SBCs zoo li lawv yog ib qho codec ntxiv xws li aptX , AAC, lossis LDAC (Android hu qhov no HD Audio) los ntawm kev ntxiv cov cim kos rau ntawm Bluetooth ntaus ntawv. Nov yog qhov nws zoo li:
Thaum lub checkbox qhib, Bluetooth suab pib kis ntawm ib tug bitrate 551 kbpsYog tias lub mloog pob ntseg txhawb kev sib txuas ceev ntawm 3 Mbit / s, lossis 452 kbpsYog hais tias lub mloog pob ntseg tsuas txhawb 2 Mbit / s.
Qhov no thaj yog suav nrog hauv qab no lwm firmwares:
- LineageOS
- Sawv Rov Los Remix
- crDroid
551 thiab 452 kbit / s tuaj qhov twg?
Bluetooth huab cua sib koom tshuab yog tsim los kom xa cov pob ntawv loj ruaj khov. Cov ntaub ntawv hloov pauv tshwm sim hauv cov slots, qhov loj tshaj plaws ntawm cov slots xa hauv ib qho kev hloov pauv yog 5. Kuj tseem muaj cov kev hloov pauv uas siv 1 lossis 3 slots, tab sis tsis yog 2 lossis 4. Hauv 5 slots koj tuaj yeem hloov mus txog 679 bytes ntawm kev sib txuas ceev. ntawm 2 Mbit / s thiab mus txog 1021 bytes ntawm qhov nrawm ntawm 3 Mbit / s, thiab ntawm 3 - 367 thiab 552 bytes, feem.
Yog tias peb xav hloov cov ntaub ntawv tsawg dua 679 lossis 1021 bytes, tab sis ntau dua 367 lossis 552 bytes, kev hloov pauv tseem yuav siv 5 qhov txuas thiab cov ntaub ntawv yuav raug xa mus rau tib lub sijhawm, uas txo cov kev hloov pauv tau zoo.
SBC nyob rau hauv Dual Channel hom, ntawm 44100 Hz suab nrog Bitpool 38 tsis, 16 blocks ib thav duab, 8 zaus ranges, encodes suab rau hauv 164 byte ntas, nrog ib tug bitrate ntawm 452 kbps.
Suab yuav tsum tau encapsulated hauv L2CAP thiab AVDTP hloov raws tu qauv, uas siv 16 bytes ntawm lub suab payload.
Yog li, ib qho kev sib kis ntawm Bluetooth nrog 5 qhov tuaj yeem ua rau 4 lub suab ntas:
679 (EDR 2 mbit/s DH5) - 4 (L2CAP) - 12 (AVDTP/RTP) - 1 (Π·Π°Π³ΠΎΠ»ΠΎΠ²ΠΎΠΊ SBC) - (164*4) = 6
Peb haum 11.7 ms ntawm cov ntaub ntawv suab rau hauv pob ntawv raug xa mus, uas yuav raug xa mus rau hauv 3.75 ms, thiab peb muaj 6 cov ntaub ntawv tsis siv nyob hauv pob ntawv.
Yog tias koj tsa lub bitpool me ntsis, nws yuav tsis tuaj yeem ntim 4 lub suab thav ntawv rau hauv ib pob. Koj yuav tsum xa 3 thav duab ib zaug, uas txo qis kev sib kis tau zoo, txo cov suab xa mus rau ib lub thav duab, thiab yuav ua rau lub suab nrov nrov hauv xov tooj cua tsis zoo.
Nyob rau hauv tib txoj kev, ib tug bitrate ntawm 551 kbit / s raug xaiv rau EDR 3 Mbit / s: nrog Bitpool 47, 16 blocks ib thav duab, 8 zaus ntau yam, tus ncej loj yog 200 bytes, nrog ib tug bitrate ntawm 551 kbit / s. Ib pob muaj 5 ntas lossis 14.6 ms suab paj nruag.
Lub algorithm rau xam tag nrho cov SBC tsis yog complex, koj yuav tau yooj yim tsis meej pem yog hais tias koj suav manually, yog li kuv ua ib tug sib tham sib lub laij lej los pab cov neeg nyiam:
Vim li cas txhua qhov no xav tau?
Tsis zoo li kev ntseeg nrov txog lub suab zoo ntawm aptX codec, ntawm qee cov ntaub ntawv nws tuaj yeem tsim cov txiaj ntsig zoo dua li SBC nrog tus qauv bitrate ntawm 328 kbps.
SBC dynamically faib quantization bits rau zaus bands nyob rau hauv qis-rau-siab. Yog tias tag nrho cov bitrate tau siv rau qhov qis thiab nruab nrab zaus, qhov siab zaus yuav raug "txiav tawm" (yuav muaj qhov ntsiag to xwb).
aptX quantizes zaus bands nrog tib tus lej ntawm cov khoom txhua lub sijhawm, uas yog vim li cas nws muaj qhov tsis tu ncua bitrate: 352 kbps rau 44.1 kHz, 384 kbps rau 48 kHz, thiab nws tsis tuaj yeem "ntsis-hloov" rau cov zaus uas xav tau lawv tshaj plaws. . Tsis zoo li SBC, aptX yuav tsis "txiav" zaus, tab sis yuav ntxiv quantization nrov rau lawv, txo cov dynamic ntau ntawm lub suab, thiab qee zaum qhia cov yam ntxwv crackling. SBC "noj cov ntsiab lus" - pov tseg cov chaw nyob ntsiag to.
Qhov nruab nrab, piv rau SBC 328k, aptX qhia txog kev cuam tshuam tsawg dua hauv suab paj nruag nrog ntau zaus, tab sis hauv suab paj nruag nrog qhov nqaim ntau thiab ntau qhov sib txawv, SBC 328k qee zaum yeej.
Cia peb xav txog ib rooj plaub tshwj xeeb. Spectrogram ntawm piano ua si kaw:
Lub zog tseem ceeb nyob hauv zaus ntawm 0 txog 4 kHz, thiab txuas ntxiv mus txog 10 kHz.
Lub spectrogram ntawm cov ntaub ntawv compressed hauv aptX zoo li no:
Thiab qhov no yog qhov SBC 328k zoo li.
Nws tuaj yeem pom tau tias SBC 328k ib ntus tag nrho tawm ntawm qhov ntau dua 16 kHz, thiab siv tag nrho cov bitrate muaj nyob rau hauv qab no tus nqi. Txawm li cas los xij, aptX tau qhia ntau qhov txawv txav mus rau qhov zaus spectrum audible rau tib neeg pob ntseg, raws li tau pom nyob rau hauv lub rho tawm thawj spectrogram los ntawm aptX spectrogram (lub brighter, ntau distortion):
Thaum SBC 328k rhuav tshem cov teeb liab tsawg dua hauv thaj tsam ntawm 0 txog 10 kHz, thiab txiav tawm qhov seem:
Lub 485k bitrate ntawm SBC tau txaus los khaws tag nrho cov zaus ntau zaus, tsis muaj kev cuam tshuam cov bands.
SBC 485k yog qhov tseem ceeb ua ntej ntawm aptX ntawm txoj kab no hauv thaj tsam ntawm 0-15 kHz, thiab nrog me me, tab sis tseem pom qhov txawv txav - hauv 15-22 kHz (qhov tsaus, qhov tsis sib haum xeeb tsawg):
.
Los ntawm kev hloov mus rau qhov siab-bitrate SBC, koj yuav tau txais suab uas feem ntau ntaus aptX ntawm ib lub mloog pob ntseg. Ntawm lub mloog pob ntseg uas txhawb nqa 3 Mbps EDR kev sib txuas, qhov me ntsis ntawm 551 kbps ua suab piv rau aptX HD.
Koj puas tuaj yeem ua ntau dua?
Lub Android thaj kuj tseem suav nrog kev xaiv kom nce qhov bitrate rau 2 Mbps EDR li. Koj tuaj yeem nce qhov bitrate ntawm 452 kbit / s mus rau 595 kbit / s, ntawm tus nqi ntawm kev txo qis kev ruaj ntseg hauv xov tooj cua nyuaj.
Nws yog txaus los teem lub persist.bluetooth.sbc_hd_higher_bitrate sib txawv rau 1:
# setprop persist.bluetooth.sbc_hd_higher_bitrate 1Qhov siab bitrate thaj ua rau tam sim no tsuas yog tau txais yuav hauv LineageOS 15.1, tab sis tsis yog hauv 16.0.
Ntaus Compatibility
SBC Dual Channel tau txais kev txhawb nqa los ntawm yuav luag txhua lub mloog pob ntseg, hais lus thiab lub taub hau tsheb. Qhov no tsis yog qhov xav tsis thoob - tus qauv yuav tsum muaj nws cov kev txhawb nqa hauv txhua yam khoom siv decoding. Muaj qee cov khoom siv me me uas hom no ua rau muaj teeb meem, tab sis cov no yog qhov sib cais.
Xav paub ntau ntxiv txog cov khoom siv sib xws tuaj yeem pom ntawm los yog .
Kev sib piv ntawm lub suab sib txawv
Kuv tau ua ib qho kev pabcuam web uas encodes suab rau SBC (nrog rau aptX thiab aptX HD) hauv lub sijhawm tiag tiag, txoj cai hauv browser. Nrog nws, koj tuaj yeem sib piv cov suab sib txawv ntawm SBC profiles thiab lwm cov codecs, yam tsis tau xa lub suab ntawm Bluetooth, ntawm txhua lub mloog pob ntseg, hais lus, thiab koj cov suab paj nruag nyiam, thiab tseem hloov pauv qhov tsis sib xws ncaj qha thaum ua si suab.
Hu rau Android Developers
Kuv tau sau ntawv mus rau ntau tus neeg tsim khoom Bluetooth pawg ntawm Google thov kom lawv xav txog suav nrog thaj ua rau thaj hauv lub ntsiab hauv Android ceg - AOSP, tab sis tsis tau txais ib qho lus teb. Kuv thaj ua rau thaj kuj tseem nyob tsis muaj lus pom los ntawm leej twg koom nrog.
Kuv yuav zoo siab yog tias kuv tuaj yeem tau txais qee qhov kev pabcuam hauv kev sib cuag nrog cov neeg tsim khoom ntawm Google thiab nqa SBC HD rau Android. Lub thaj hauv gerrit twb dhau los lawm (qhov no yog ib qho kev hloov kho thaum ntxov), thiab kuv yuav hloov kho nws yog tias cov neeg tsim khoom txaus siab rau kuv cov kev hloov pauv (nws tsis yooj yim rau kuv hloov kho nws, Kuv tsis muaj cov cuab yeej siv tau nrog Android Q. ).
xaus
Cov neeg siv ntawm cov smartphones nrog LineageOS, Sawv Rov Los Remix thiab crDroid firmware tuaj yeem txaus siab rau kev txhim kho suab zoo tam sim no, tsuas yog qhib qhov kev xaiv hauv Bluetooth ntaus ntawv. Cov neeg siv Linux kuj tuaj yeem tau txais SBC bitrate nce ntxiv los ntawm kev txhim kho , uas, ntawm lwm yam, ntxiv kev txhawb nqa rau aptX, aptX HD thiab FastStream codecs.
Tau qhov twg los: www.hab.com