Chifukwa cha kuchuluka kwa mafoni a m'manja opanda 3.5 mm audio jack, mahedifoni opanda zingwe a Bluetooth akhala njira yayikulu yoti anthu ambiri azimvera nyimbo ndikulankhulana pamutu.
Opanga zida zopanda zingwe nthawi zonse samalemba tsatanetsatane wazinthu, ndipo zolemba za Bluetooth pa intaneti zimatsutsana, nthawi zina zolakwika, osalankhula za mawonekedwe onse, ndipo nthawi zambiri amatengera zomwezo zomwe sizikugwirizana ndi zenizeni.
Tiyeni tiyese kumvetsetsa protocol, kuthekera kwa Bluetooth OS stacks, mahedifoni ndi okamba, Bluetooth codecs nyimbo ndi kulankhula, kupeza chimene chimakhudza khalidwe zimafala phokoso ndi latency, kuphunzira kusonkhanitsa ndi decode zambiri za anathandiza codecs ndi chipangizo china. kuthekera.
TL; DR:
- SBC - codec wamba
- Mahedifoni ali ndi equalizer yawo ndikusintha pambuyo pa codec iliyonse padera
- aptX siili bwino monga momwe amalengezera
- LDAC ndi malonda a bullshit
- Khalidwe loyimba foni likadali loyipa
- Mutha kuyika ma encoders a C mumsakatuli wanu powaphatikiza mu WebAssembly kudzera pa emscripten, ndipo sangachedwe kwambiri.
Nyimbo kudzera pa Bluetooth
Chigawo chogwira ntchito cha Bluetooth chimatsimikiziridwa ndi mbiri - tsatanetsatane wa ntchito zinazake. Kutsatsa kwanyimbo kwa Bluetooth kumagwiritsa ntchito mbiri yapamwamba kwambiri ya A2DP yapadziko lonse lapansi. Muyezo wa A2DP unakhazikitsidwa mu 2003 ndipo sunasinthe kwenikweni kuyambira pamenepo.
Mkati mwa mbiriyi, 1 codec yovomerezeka ya SBC yocheperako, yopangidwira Bluetooth, ndi zina 3 zowonjezera ndizokhazikika. Ndikothekanso kugwiritsa ntchito ma codec osalembedwa pazomwe mukukhazikitsa.
Kuyambira Juni 2019 tili okhala ndi ma codec 14 A2DP:
- Mtengo wa SBC β yokhazikika mu A2DP, yothandizidwa ndi zida zonse
- MPEG-1/2 Layer 1/2/3 β yokhazikika mu A2DP: yodziwika bwino , yogwiritsidwa ntchito mu digito TV , ndi osadziwika
- MPEG-2/4 AAC β yokhazikika mu A2DP
- Malingaliro a kampani ATRAC β codec yakale yochokera ku Sony, yokhazikika mu A2DP
- LDAC β codec yatsopano yochokera ku Sony
- aptX β codec kuyambira 1988
- aptXHD β yofanana ndi aptX, yokhala ndi zosankha zosiyanasiyana
- aptX Low Latency β codec yosiyana kotheratu, palibe kukhazikitsa mapulogalamu
- aptX Kusintha β codec ina yochokera ku Qualcomm
- FastStream β pseudo codec, bidirectional SBC kusinthidwa
- Mtengo wa HWA LHDC β codec yatsopano yochokera ku Huawei
- Samsung HD β mothandizidwa ndi zida ziwiri
- Samsung Scalable β mothandizidwa ndi zida ziwiri
- Samsung UHQ-BT β mothandizidwa ndi zida ziwiri
N'chifukwa chiyani timafunikira ma codec nkomwe, mumafunsa, pamene Bluetooth ili ndi EDR, yomwe imakulolani kusamutsa deta pa liwiro la 2 ndi 3 Mbit / s, komanso kwa PCM yosakanizidwa ndi njira ziwiri 16-bit, 1.4 Mbit / s ndi yokwanira?
Kutumiza kwa data kudzera pa Bluetooth
Pali mitundu iwiri ya kusamutsa deta mu Bluetooth: Asynchronous Connection Less (ACL) ya kusamutsidwa kosagwirizana popanda kukhazikitsidwa kolumikizana, ndi Synchronous Connection Oriented (SCO), yosinthira ma synchronous ndi kukambirana koyambirira.
Kutumiza kumachitika pogwiritsa ntchito njira yogawa nthawi ndikusankha njira yopatsira paketi iliyonse padera (Frequency-Hop/Time-Division-Duplex, FH/TDD), yomwe nthawiyo imagawidwa mu 625-microsecond intervals yotchedwa mipata. Chimodzi mwazipangizozi chimadutsa m'malo owerengeka, chinacho m'malo owerengeka. Phukusi lopatsirana limatha kukhala ndi mipata 1, 3 kapena 5, kutengera kukula kwa deta ndi mtundu womwe waperekedwa, pakadali pano, kufalitsa ndi chipangizo chimodzi kumachitika m'mipata yofananira komanso yosamvetseka mpaka kumapeto kwa kufalitsa. Pazonse, mpaka mapaketi a 1600 amatha kulandiridwa ndikutumizidwa pamphindikati, ngati aliyense wa iwo ali ndi 1 kagawo, ndipo zida zonse zimafalitsa ndikulandila china chake popanda kuyimitsa.
2 ndi 3 Mbit/s ya EDR, yomwe ingapezeke muzolengeza ndi pa webusayiti ya Bluetooth, ndizomwe zimasamutsa tchanelo cha data yonse yonse (kuphatikiza mitu yaukadaulo yama protocol onse omwe deta iyenera kuyikidwa), mbali ziwiri. nthawi imodzi. Liwiro lenileni losamutsa deta lidzasiyana kwambiri.
Kutumiza nyimbo, njira ya asynchronous imagwiritsidwa ntchito, pafupifupi nthawi zonse kugwiritsa ntchito mapaketi ngati 2-DH5 ndi 3-DH5, omwe amanyamula kuchuluka kwa data mu EDR mode ya 2 Mbit / s ndi 3 Mbit / s, motsatana, ndikukhala nthawi 5. -kugawana mipata.
Kuyimilira kwapang'onopang'ono pogwiritsa ntchito mipata 5 ndi chipangizo chimodzi ndi kagawo kamodzi ndi china (DH1/DH5):
Chifukwa cha mfundo ya kugawanika kwa nthawi ya ma airwaves, timakakamizika kudikirira nthawi ya 625-microsecond pambuyo potumiza paketi ngati chipangizo chachiwiri sichikutumiza chirichonse kwa ife kapena kutumiza paketi yaying'ono, ndi nthawi yochulukirapo ngati chipangizo chachiwiri chikutumiza. m'mapaketi akuluakulu. Ngati zida zopitilira chimodzi zilumikizidwa ndi foni (mwachitsanzo, mahedifoni, mawotchi ndi chibangili cholimbitsa thupi), ndiye kuti nthawi yosinthira imagawidwa pakati pa onsewo.
Kufunika kophatikizira zomvera mumayendedwe apadera a L2CAP ndi AVDTP kumatenga ma byte 16 kuchokera pamlingo womwe ungatheke wamawu operekedwa.
Mtundu wa phukusi
Chiwerengero cha mipata
Max. kuchuluka kwa ma byte mu paketi
Max. chiwerengero cha ma byte cha A2DP payload
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
1414 ndi 1429 kbps sizokwanira kufalitsa ma audio osakhazikika muzochitika zenizeni, ndi phokoso la 2.4 GHz komanso kufunika kotumiza deta ya utumiki. EDR 3 Mbit / s imafuna mphamvu yotumizira ndi phokoso pamlengalenga, choncho, ngakhale mumayendedwe a 3-DH5, kufalitsa kwa PCM omasuka sikutheka, padzakhala kusokoneza kwakanthawi kochepa, ndipo chirichonse chidzangogwira ntchito patali. mamita awiri.
M'malo mwake, ngakhale 990 kbit/s audio stream (LDAC 990 kbit/s) ndizovuta kufalitsa.
Tiyeni tibwerere ku ma codecs.
Mtengo wa SBC
Codec yofunikira pazida zonse zomwe zimathandizira muyezo wa A2DP. Codec yabwino komanso yoyipa kwambiri nthawi yomweyo.
Zitsanzo pafupipafupi
Kuzama pang'ono
Bitrate
Thandizo la encoding
Thandizo la decoding
16, 32, 44.1, 48 kHz
16 pang'ono
10-1500 kbps
Zida zonse
Zida zonse
SBC ndi codec yosavuta komanso yothamanga kwambiri, yokhala ndi mtundu wakale wa psychoacoustic (kubisa mawu abata okha), pogwiritsa ntchito adaptive pulse code modulation (APCM).
Mafotokozedwe a A2DP amalimbikitsa mbiri ziwiri kuti zigwiritsidwe ntchito: Middle Quality ndi High Quality.
Codec ili ndi zoikamo zambiri zomwe zimakupatsani mwayi wowongolera kuchedwa kwa algorithmic, kuchuluka kwa zitsanzo mu chipika, kugawa pang'onopang'ono, koma pafupifupi kulikonse magawo omwe akulimbikitsidwa pamatchulidwe amagwiritsidwa ntchito: Joint Stereo, 8 frequency band, 16 midadada mu. chimango audio, Loudness pang'ono kugawa njira.
SBC imathandizira kusintha kwamphamvu kwa Bitpool parameter, yomwe imakhudza mwachindunji bitrate. Ngati ma airwaves atsekedwa, mapaketi atayika, kapena zipangizo zili patali kwambiri, gwero la audio likhoza kuchepetsa Bitpool mpaka kulankhulana kubwerere mwakale.
Ambiri opanga mahedifoni amayika mtengo wapamwamba wa Bitpool ku 53, womwe umalepheretsa bitrate kukhala 328 kilobits pamphindikati mukamagwiritsa ntchito mbiri yovomerezeka.
Ngakhale wopanga mahedifoni ayika mtengo wapamwamba wa Bitpool pamwamba pa 53 (zitsanzo zotere zimapezeka, mwachitsanzo: Beats SoloΒ³, JBL Everest Elite 750NC, Apple AirPods, zomwe zimapezekanso pa olandila ndi mayunitsi amutu wamagalimoto), ndiye kuti OS ambiri sangalole. kugwiritsa ntchito kuchuluka kwa ma bitrate chifukwa chokhazikitsa malire amtengo wamkati mu stacks za Bluetooth.
Kuphatikiza apo, opanga ena amayika mtengo wapamwamba wa Bitpool kukhala wotsika pazida zina. Mwachitsanzo, kwa Bluedio T ndi 39, kwa Samsung Gear IconX ndi 37, yomwe imapereka kusamveka bwino.
Zoletsa zopanga za opanga ma stacks a Bluetooth mwina zidayamba chifukwa chosagwirizana ndi zida zina zomwe zili ndi mitengo yayikulu ya Bitpool kapena mbiri yofananira, ngakhale atanena kuti awathandizira, komanso kuyezetsa kosakwanira pakutsimikizira. Zinali zosavuta kuti olemba ma stacks a Bluetooth adzichepetse okha kuti agwirizane ndi mbiri yovomerezeka, m'malo mopanga nkhokwe za zipangizo zolakwika (ngakhale tsopano amachita izi kwa ntchito zina zolakwika).
SBC imagawira ma quantization bits kuma band pafupipafupi motsika mpaka-mmwamba, okhala ndi zolemera zosiyanasiyana. Ngati bitrate yonse idagwiritsidwa ntchito pamayendedwe otsika ndi apakati, ma frequency apamwamba "adzadulidwa" (padzakhala chete m'malo mwake).
Chitsanzo SBC 328 kbps. Pamwamba ndi choyambirira, pansi ndi SBC, nthawi ndi nthawi kusinthana pakati pa mayendedwe. The zomvetsera mu kanema wapamwamba ntchito FLAC lossless psinjika codec. Kugwiritsa ntchito FLAC mu chidebe cha mp4 sikuli kovomerezeka, kotero sikukutsimikiziridwa kuti msakatuli wanu azisewera, koma ziyenera kugwira ntchito m'mawonekedwe atsopano a Chrome ndi Firefox. Ngati mulibe phokoso, mukhoza kukopera wapamwamba ndi kutsegula mu zonse unachitikira kanema wosewera mpira.
ZZ Top - Munthu Wovala Wakuthwa
Makanema akuwonetsa nthawi yosinthira: SBC imadula nthawi ndi nthawi mawu opanda phokoso kuposa 17.5 kHz, ndipo samagawira bandi iliyonse yopitilira 20 kHz. Ma spectrogram athunthu akupezeka podina (1.7 MB).
Sindikumva kusiyana kulikonse pakati pa choyambirira ndi SBC panjirayi.
Tiyeni titenge china chatsopano ndikutsanzira zomvera zomwe zikanapezeka pogwiritsa ntchito mahedifoni a Samsung Gear IconX okhala ndi Bitpool 37 (pamwambapa - chizindikiro choyambirira, pansipa - SBC 239 kbps, audio mu FLAC).
Kudzikonda Mopanda Mizinda - Umboni
Ndikumva kung'ung'udza, kamvekedwe kakang'ono ka stereo komanso phokoso losasangalatsa la "clunking" m'mawu okwera kwambiri.
Ngakhale SBC ndi codec yosinthika kwambiri, imatha kukhazikitsidwa kuti ikhale yocheperako, imapereka mawu abwino kwambiri pama bitrate apamwamba (452+ kbps) ndipo ndiyabwino kwambiri kwa anthu ambiri omwe ali ndi High Quality (328 kbps), chifukwa muyezo wa A2DP sunatchule mbiri yokhazikika (koma imangopereka malingaliro), opanga ma stack akhazikitsa zoletsa zopangira Bitpool, magawo amawu omwe amafalitsidwa samawonetsedwa pamawonekedwe a ogwiritsa ntchito, ndipo opanga mahedifoni ali omasuka kuyika zokonda zawo ndipo samatero. kuwonetsa mtengo wa Bitpool muzolemba zaukadaulo zamtunduwu, codec idadziwika bwino chifukwa cha mawu ake otsika, ngakhale ili si vuto ndi codec.
Bitpool parameter imakhudza mwachindunji bitrate mkati mwa mbiri imodzi. Mtengo womwewo wa Bitpool 53 ukhoza kupatsa onse bitrate ya 328 kbps yokhala ndi mbiri yabwino kwambiri, ndi 1212 kbps yokhala ndi Dual Channel ndi 4 frequency band, chifukwa chake olemba OS, kuwonjezera pa zoletsa pa Bitpool, adakhazikitsa malire ndi kupitilira. Bitrate. Monga ndikuwonera, izi zidayamba chifukwa cha cholakwika cha muyezo wa A2DP: kunali koyenera kukambirana ndi bitrate, osati Bitpool.
Table yothandizira mphamvu za SBC mu OS zosiyanasiyana:
OS
Zitsanzo zothandizidwa
Malire max. Bitpool
Malire max. Bitrate
Mtundu wa Bitrate
Kusintha kwamphamvu kwa Bitpool
Windows 10
44.1 ΠΊΠΡ
53
512 kbps
328 kbps
β*
Linux (BlueZ + PulseAudio)
16, 32, 44.1, 48 kHz
64 (zolumikizira zomwe zikubwera), 53 (zolumikizira zomwe zikutuluka)
Palibe malire
328 kbps
β*
MacOS High Sierra
44.1 ΠΊΠΡ
64, kusakhulupirika 53***
Zosadziwika
328 kbps
β
Android 4.4-9
44.1/48 kHz**
53
328 kbps
328 kbps
β
Android 4.1-4.3.1
44.1, 48 kHz**
53
229 kbps
229 kbps
β
Blackberry OS 10
48 ΠΊΠΡ
53
Palibe malire
328 kbps
β
* Bitpool imangotsika, koma sichimawonjezeka, ngati zinthu zosinthira zikuyenda bwino. Kuti mubwezeretse Bitpool muyenera kusiya kusewera, dikirani masekondi angapo ndikuyambitsanso nyimboyo.
** Mtengo wokhazikika umadalira zokonda za stack zomwe zafotokozedwa polemba firmware. Mu Android 8/8.1 pafupipafupi ndi 44.1 kHz kapena 48 kHz, kutengera zosintha panthawi yophatikiza, m'mitundu ina 44.1 kHz ndi 48 kHz amathandizidwa nthawi imodzi.
*** Mtengo wa Bitpool ukhoza kuwonjezeka mu pulogalamu ya Bluetooth Explorer.
aptX ndi aptX HD
aptX ndi codec yosavuta komanso yofulumira, yopanda psychoacoustics, yogwiritsira ntchito kusintha kwa ma pulse code modulation (). Idawonekera chakumapeto kwa 1988 (tsiku lolemba ya February 1988), Bluetooth isanachitike, idagwiritsidwa ntchito makamaka pazida zamawu opanda zingwe. Panopa ili ndi Qualcomm, imafuna chilolezo komanso malipiro. Pofika chaka cha 2014: $6000 nthawi imodzi ndi β$1 pachida chilichonse, pamagulu a zida za 10000 (, p. 16).
aptX ndi aptX HD ndi ma codec omwewo, okhala ndi ma encoding osiyanasiyana.
Codec ili ndi gawo limodzi lokha - kusankha sampuli pafupipafupi. Pali, komabe, kusankha kwa nambala / mawonekedwe a mayendedwe, koma pazida zonse zomwe ndikudziwa (zidutswa 70+) ndi Stereo yokhayo yomwe imathandizidwa.
Codec
Zitsanzo pafupipafupi
Kuzama pang'ono
Bitrate
Thandizo la encoding
Thandizo la decoding
aptX
16, 32, 44.1, 48 kHz
16 pang'ono
128 / 256 / 352 / 384 kbps (malingana ndi zitsanzo)
Windows 10 (desktop ndi mafoni), macOS, Android 4.4+/7*, Blackberry OS 10
Zida zambiri zamawu (hardware)
* Zosintha mpaka 7 zimafunikira kusinthidwa kwa stack ya Bluetooth. Kodeki imagwira ntchito ngati wopanga zida za Android ali ndi chilolezo cha codec kuchokera ku Qualcomm (ngati OS ili ndi malaibulale ojambulira).
aptX imagawa ma audio mu 4 ma frequency band ndikuwawerengera ndi kuchuluka kwa ma bits nthawi zonse: 8 bits kwa 0-5.5 kHz, 4 bits kwa 5.5-11 kHz, 2 bits kwa 11-16.5 kHz, 2 bits kwa 16.5-22 kHz ( ziwerengero za chitsanzo cha 44.1 kHz).
Chitsanzo cha aptX audio (pamwamba - siginecha yoyambirira, pansi - aptX, mawonedwe amakanema akumanzere okha, amamveka mu FLAC):
Kukwera kunakhala kofiira pang'ono, koma simunamve kusiyana kwake.
Chifukwa cha kugawa kokhazikika kwa ma quantization bits, codec siyingasinthe "ma bits" kupita ku ma frequency omwe amawafuna kwambiri. Mosiyana ndi SBC, aptX "sidzadula" ma frequency, koma idzawonjezera phokoso la quantization kwa iwo, kuchepetsa kusinthasintha kwamawu.
Sitiyenera kuganiziridwa kuti kugwiritsa ntchito, mwachitsanzo, ma bits a 2 pa gulu kumachepetsa kusinthasintha kwa 12 dB: ADPCM imalola mpaka 96 dB yamtundu wamtundu wamtundu ngakhale pogwiritsa ntchito 2 quantization bits, koma ndi chizindikiro china.
ADPCM imasunga kusiyana kwa manambala pakati pa zitsanzo zamakono ndi chitsanzo chotsatira, m'malo mosunga mtengo wathunthu monga PCM. Izi zimakuthandizani kuti muchepetse zofunikira pa kuchuluka kwa ma bits ofunikira kuti musunge zomwezo (popanda kutayika) kapena pafupifupi zofanana (ndi cholakwika chaching'ono chozungulira). Kuti muchepetse zolakwika zozungulira, matebulo a coefficient amagwiritsidwa ntchito.
Popanga codec, olembawo adawerengera ma coefficients a ADPCM pa seti ya mafayilo amawu a nyimbo. Kuyandikira kwa siginecha yamawu ndikuyimba kwa nyimbo zomwe matebulo adamangidwapo, zolakwika zochepa za quantization (phokoso) aptX imapanga.
Chifukwa cha izi, kuyesa kopanga nthawi zonse kumabweretsa zotsatira zoyipa kuposa nyimbo. Ndinapanga chitsanzo chapadera chomwe aptX amawonetsa zotsatira zoipa - sine wave yokhala ndi ma frequency a 12.4 kHz (pamwambapa - chizindikiro choyambirira, pansipa - aptX. Audio mu FLAC. Tsitsani voliyumu!):
Spectrum graph:
Phokoso limamveka bwino.
Komabe, ngati mupanga sine wave yokhala ndi matalikidwe ang'onoang'ono kuti ikhale chete, phokosolo lidzakhalanso lopanda phokoso, kusonyeza kusinthasintha kwakukulu:
Kuti mumve kusiyana pakati pa nyimbo yoyambira ndi yopanikizidwa, mutha kutembenuza siginecha imodzi ndikuwonjezera mayendedwe a nyimbo ndi tchanelo. Njirayi, mwachizoloΕ΅ezi, ndiyolakwika, ndipo sizingapereke zotsatira zabwino ndi ma codec ovuta kwambiri, koma makamaka kwa ADPCM ndizoyenera.
Mizu imatanthawuza kusiyana kwakukulu kwa ma siginecha ali pamlingo wa -37.4 dB, womwe suli wochuluka panyimbo zotere.
aptXHD
aptX HD si codec yoyimirira - ndi mbiri yabwino ya aptX codec. Zosinthazo zidakhudza kuchuluka kwa ma bits omwe amaperekedwa pamasinthidwe afupipafupi: ma bits 10 a 0-5.5 kHz, 6 bits a 5.5-11 kHz, 4 bits a 11-16.5 kHz, 4 bits a 16.5-22 kHz (manambala a 44.1 kHz). .
Codec
Zitsanzo pafupipafupi
Kuzama pang'ono
Bitrate
Thandizo la encoding
Thandizo la decoding
aptXHD
16, 32, 44.1, 48 kHz
24 biti
192 / 384 / 529 / 576 kbps (malingana ndi zitsanzo)
Android 8+*
Zida zina zomvera (hardware)
* Zosintha mpaka 7 zimafunikira kusinthidwa kwa stack ya Bluetooth. Kodeki imagwira ntchito ngati wopanga zida za Android ali ndi chilolezo cha codec kuchokera ku Qualcomm (ngati OS ili ndi malaibulale ojambulira).
Zocheperako kuposa aptX: zikuwoneka kuti zimafunikira chilolezo chosiyana ndi Qualcomm, komanso ndalama zolekanitsa zalayisensi.
Tiyeni tibwereze chitsanzo ndi sine wave pa 12.4 kHz:
Zabwino kwambiri kuposa aptX, komabe phokoso pang'ono.
aptX Low Latency
Codec yochokera ku Qualcomm yomwe ilibe kanthu kofanana ndi aptX yokhazikika ndi aptX HD, kutengera chidziwitso chochepa cha anthu omwe akukhudzidwa ndi chitukuko chake. Zapangidwira kuti zizitha kutumizirana ma audio otsika (makanema, masewera), pomwe kuchedwa kwa mawu sikungasinthidwe ndi mapulogalamu. Palibe kukhazikitsidwa kwa mapulogalamu odziwika a ma encoder ndi ma decoder; amathandizidwa ndi ma transmitter, olandila, mahedifoni ndi okamba, koma osati ndi mafoni ndi makompyuta.
Zitsanzo pafupipafupi
Bitrate
Thandizo la encoding
Thandizo la decoding
44.1 ΠΊΠΡ
276/420 kbps
Ma transmitter ena (hardware)
Zida zina zomvera (hardware)
AAC
AAC, kapena Advanced Audio Coding, ndi codec yovuta kwambiri yokhala ndi psychoacoustic model. Amagwiritsidwa ntchito kwambiri pamawu pa intaneti, achiwiri kutchuka pambuyo pa MP3. Imafunika chilolezo ndi malipiro: $ 15000 nthawi imodzi (kapena $ 1000 kwa makampani omwe ali ndi antchito osakwana 15) + $ 0.98 pazida zoyamba za 500000 ().
The codec ndi standardized mkati MPEG-2 ndi MPEG-4 specifications, ndipo mosiyana ndi maganizo olakwika, si wa Apple.
Zitsanzo pafupipafupi
Bitrate
Thandizo la encoding
Thandizo la decoding
8 - 96 kHz
8 - 576 kbps (ya stereo), 256 - 320 kbps (yofanana ndi Bluetooth)
MacOS, Android 7+*, iOS
Zida zambiri zamawu (hardware)
* pokhapokha pazida zomwe opanga amalipira ndalama zololeza
iOS ndi macOS amagwiritsa ntchito encoder yapamwamba kwambiri ya Apple ya AAC kuti ipereke nyimbo zapamwamba kwambiri zomwe zingatheke. Android imagwiritsa ntchito encoder yachiwiri yapamwamba kwambiri ya Fraunhofer FDK AAC, koma imatha kugwiritsa ntchito zida zosiyanasiyana zomangidwa papulatifomu (SoC) yokhala ndi ma encoding osadziwika. , mtundu wa kabisidwe wa AAC wama foni osiyanasiyana a Android umasiyana kwambiri:
Zida zambiri zamawu opanda zingwe zimakhala ndi bitrate yopitilira 320 kbps ya AAC, zina zimangothandizira 256 kbps. Ma bitrate ena ndi osowa kwambiri.
AAC imapereka khalidwe labwino kwambiri pa 320 ndi 256 kbps bitrate, koma imayenera , komabe, ndizovuta kumva kusiyana kulikonse ndi choyambirira pa iOS pa bitrate ya 256 kbps ngakhale ndi ma encoding angapo otsatizana; ndi encoding imodzi, mwachitsanzo, MP3 320 kbps mpaka AAC 256 kbps, zotayika zitha kunyalanyazidwa.
Mofanana ndi ma codec ena a Bluetooth, nyimbo iliyonse imasinthidwa ndikusinthidwa ndi codec. Mukamvetsera nyimbo zamtundu wa AAC, imasinthidwa koyamba ndi OS, kenako imayikidwanso mu AAC kuti itumizidwe kudzera pa Bluetooth. Izi ndizofunikira pakusakaniza ma audio angapo, monga nyimbo ndi zidziwitso za uthenga watsopano. iOS ndi chimodzimodzi. Pa Intaneti mungapeze mawu ambiri kuti iOS nyimbo AAC mtundu si transcoded pamene opatsirana kudzera Bluetooth, zimene si zoona.
MP1/2/3
Ma codec a banja la MPEG-1/2 Part 3 amakhala ndi MP3 yodziwika bwino komanso yogwiritsidwa ntchito kwambiri, MP2 yocheperako (yomwe imagwiritsidwa ntchito makamaka pa TV ya digito ndi wailesi), komanso MP1 yosadziwika bwino.
Ma codec akale a MP1 ndi MP2 samathandizidwa konse: sindinapeze mahedifoni aliwonse kapena stack ya Bluetooth yomwe ingayimbire kapena kuyiyika.
Kujambula kwa MP3 kumathandizidwa ndi mahedifoni ena, koma ma encoding sagwiritsidwa ntchito pa stack iliyonse yamakono. Zikuoneka kuti gulu lachitatu BlueSoleil stack kwa Windows akhoza encode MP3 ngati inu pamanja kasinthidwe wapamwamba, koma kwa ine khazikitsa kumabweretsa BSoD pa Windows 10. Mapeto - codec kwenikweni sangathe ntchito Bluetooth audio.
M'mbuyomu, mu 2006-2008, asanafalikire muyezo wa A2DP pazida, anthu amamvetsera nyimbo za MP3 pamutu wa Nokia BH-501 kudzera pa pulogalamu ya MSI BluePlayer, yomwe idapezeka pa Symbian ndi Windows Mobile. Panthawiyo, mapangidwe a OS a mafoni a m'manja amalola mwayi wopeza ntchito zambiri zotsika, ndipo pa Windows Mobile zinali zotheka kukhazikitsa ma stacks a Bluetooth.
Patent yomaliza ya MP3 codec yatha, kugwiritsa ntchito codec sikufuna chindapusa cha chilolezo kuyambira pa Epulo 23, 2017.
Ngati chiphaso chotalika kwambiri chomwe chatchulidwa m'mawu omwe tawatchulawa chikuyesedwa ngati muyeso, ndiye kuti ukadaulo wa MP3 udakhala wopanda patent ku United States pa Epulo 16, 2017 pomwe Patent ya US 6,009,399, yosungidwa ndi kuyendetsedwa ndi Technicolor, idatha.
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Zitsanzo pafupipafupi
Bitrate
Thandizo la encoding
Thandizo la decoding
16 - 48 kHz
8 - 320 kbps
Osathandizidwa kulikonse
Zida zina zomvera (hardware)
LDAC
Kodeki yatsopano komanso yokwezedwa ya "Hi-Res" yochokera ku Sony, yomwe imathandizira kusanja mpaka 96 kHz ndi 24-bit bitrate, yokhala ndi ma bitrate mpaka 990 kbps. Imalengezedwa ngati audiophile codec, m'malo mwa ma codec a Bluetooth omwe alipo. Ili ndi ntchito yosinthira bitrate yosinthika, kutengera momwe zinthu ziliri pawailesi.
LDAC encoder () imaphatikizidwa mu phukusi lokhazikika la Android, kotero kusungitsa kumathandizira pa foni yamakono ya Android kuyambira ndi mtundu wa OS 8. Palibe ma decoder omwe amapezeka mwaufulu, mawonekedwe a codec sapezeka kwa anthu wamba, komabe, poyang'ana koyamba pa encoder, mawonekedwe amkati a codec ndi ofanana ndi - Codec ya Sony yomwe imagwiritsidwa ntchito mu PlayStation 4 ndi Vita: onse amagwira ntchito pafupipafupi, amagwiritsa ntchito kusintha kwa discrete cosine (MDCT) ndi kuphatikizika pogwiritsa ntchito algorithm ya Huffman.
Thandizo la LDAC limaperekedwa pafupifupi ndi mahedifoni ochokera ku Sony. Kutha kuzindikira LDAC nthawi zina kumapezeka pamakutu ndi ma DAC kuchokera kwa opanga ena, koma kawirikawiri.
Zitsanzo pafupipafupi
Bitrate
Thandizo la encoding
Thandizo la decoding
44.1 - 96 kHz
303/606/909 kbit/s (kwa 44.1 ndi 88.2 kHz), 330/660/990 kbit/s (kwa 48 ndi 96 kHz)
Android 8 +
Mahedifoni ena a Sony ndi zida zina zochokera kwa opanga ena (hardware)
Kutsatsa LDAC ngati Hi-Res codec kumawononga chigawo chake chaukadaulo: ndizopusa kugwiritsa ntchito ma frequency osamveka m'khutu la munthu ndikuwonjezera kuya pang'ono, pomwe sikukwanira kufalitsa CD-quality (44.1/16) popanda kutaya. . Mwamwayi, codec ali modes awiri opaleshoni: CD zomvetsera kufala ndi Hi-Res audio kufala. Poyamba, ma bits 44.1 kHz/16 okha ndi omwe amafalitsidwa pamlengalenga.
Popeza pulogalamu ya LDAC decoder sichipezeka mwaulere, ndizosatheka kuyesa codec popanda zida zowonjezera zomwe zimatsitsa LDAC. Malinga ndi zotsatira za kuyesa kwa LDAC pa DAC ndi chithandizo chake, chomwe mainjiniya a SoundGuys.com adalumikiza kudzera pa digito ndikujambula mawu otuluka pazizindikiro zoyesa, LDAC 660 ndi 990 kbps mumayendedwe amtundu wa CD imapereka chidziwitso-ku- chiΕ΅erengero cha phokoso bwinoko pang'ono kuposa cha aptX HD.
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LDAC imathandiziranso ma bitrate osinthika kunja kwa mbiri yokhazikitsidwa - kuchokera pa 138 kbps mpaka 990 kbps, koma momwe ndingadziwire, Android imangogwiritsa ntchito mbiri yokhazikika 303/606/909 ndi 330/660/990 kbps.
Ma codec ena
Ma codec ena a A2DP sagwiritsidwa ntchito kwambiri. Thandizo lawo mwina silinakhalepo kapena likupezeka pamitundu ina ya mahedifoni ndi mafoni.
Codec ya ATRAC yokhazikika mu A2DP sinagwiritsidwepo ntchito ngati Bluetooth codec ngakhale ndi Sony okha, Samsung HD, Samsung Scalable ndi Samsung UHQ-BT codec ali ndi chithandizo chochepa kwambiri kuchokera ku makina otumizira ndi kulandira, ndipo HWA LHDC ndi yatsopano kwambiri ndipo imathandizidwa katatu. (?) zipangizo.
Thandizo la codec pazida zomvera
Sikuti opanga onse amasindikiza zidziwitso zolondola za ma codec omwe amathandizidwa ndi mahedifoni opanda zingwe, okamba, olandila kapena ma transmitters. Nthawi zina zimachitika kuti kuthandizira kwa codec inayake ndikungotumiza, koma osati kulandila (koyenera kwa olandila ophatikizika), ngakhale wopanga amangolengeza "thandizo", popanda zolemba (ndikuganiza kuti kupatsidwa chilolezo chosiyana ndi ma encoder ndi ma decoder ena. ma codecs ndi omwe amachititsa izi). Pazida zotsika mtengo, simungapeze chithandizo cha aptX chomwe chalengezedwa.
Tsoka ilo, mawonekedwe a machitidwe ambiri ogwiritsira ntchito sawonetsa codec yomwe imagwiritsidwa ntchito kulikonse. Zambiri za izi zimapezeka mu Android, kuyambira mtundu 8, ndi macOS. Komabe, ngakhale mu ma OS awa, ma codec okhawo omwe amathandizidwa ndi foni/kompyuta ndi mahedifoni ndiwo aziwonetsedwa.
Kodi mungadziwe bwanji ma codec omwe chipangizo chanu chimathandizira? Jambulani ndikusanthula kutayira kwa magalimoto ndi magawo a zokambirana za A2DP!
Izi zitha kuchitika pa Linux, macOS ndi Android. Pa Linux mutha kugwiritsa ntchito Wireshark kapena hcidump, pa macOS mutha kugwiritsa ntchito Bluetooth Explorer, ndipo pa Android mutha kugwiritsa ntchito njira yosungira ya Bluetooth HCI, yomwe imapezeka pazida zopanga mapulogalamu. Mudzalandira kutayira mu mtundu wa btsnoop, womwe ukhoza kukwezedwa mu Wireshark analyzer.
Samalani: kutaya koyenera kungapezeke polumikiza kuchokera ku foni/kompyuta yanu kupita ku mahedifoni/zokamba (zilibe kanthu kuti zingamveke zoseketsa bwanji)! Mahedifoni amatha kukhazikitsa kulumikizana ndi foni, pomwe amapempha mndandanda wa ma codec kuchokera pafoni, osati mosemphanitsa. Kuti muwonetsetse kuti kutayira koyenera kwajambulidwa, choyamba sinthani chipangizocho ndikuphatikiza foni yanu ndi mahedifoni mukujambula.
Gwiritsani ntchito zosefera zotsatirazi kuti musefe kuchuluka kwa magalimoto osayenera:
btavdtp.signal_idChifukwa chake, muyenera kuwona zofanana ndi izi:
Mutha kudina chinthu chilichonse mu lamulo la GetCapabilities kuti muwone tsatanetsatane wa codec.
Wireshark sadziwa zizindikiritso zonse za codec, kotero ma codec ena amayenera kusinthidwa pamanja, kuyang'ana patebulo lozindikiritsa pansipa:
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 aptXKuti ndisasanthula zotayira pamanja, ndidapanga ntchito yomwe imangosanthula zonse zokha:
Kufananiza ma codecs. Ndi codec iti yabwino?
Codec iliyonse ili ndi zabwino zake ndi zovuta zake.
aptX ndi aptX HD amagwiritsa ntchito mbiri zolimba zomwe sizingasinthidwe popanda kusintha encoder ndi decoder. Wopanga mafoni kapena wopanga mahedifoni sangasinthe zinthu za bitrate kapena aptX encoding. Mwiniwake wa codec, Qualcomm, amapereka encoder yofotokozera ngati laibulale. Mfundo izi ndi mphamvu ya aptX - mumadziwa pasadakhale kuti mupeza phokoso lanji, popanda "buts".
SBC, mosiyana, ili ndi magawo ambiri osinthika, dynamic bitrate (encoder ikhoza kuchepetsa parameter ya bitpool ngati ma airwaves ali otanganidwa), ndipo alibe mbiri yolimba, koma "zapakatikati" zovomerezeka ndi "zapamwamba" zomwe zinali anawonjezera ku A2DP specifications mu 2003 chaka. "Makhalidwe apamwamba" salinso apamwamba kwambiri masiku ano, ndipo ma stacks ambiri a Bluetooth samakulolani kugwiritsa ntchito magawo bwino kuposa mbiri ya "high quality", ngakhale kuti palibe zoletsa zamakono pa izi.
Bluetooth SIG ilibe encoder ya SBC ngati laibulale, ndipo opanga amazikhazikitsa okha.
Izi ndi zofooka za SBC - sizidziwikiratu kuti ndimtundu wanji womwe ungayembekezere kuchokera ku chipangizo china. SBC imatha kutulutsa zomvera zotsika komanso zapamwamba kwambiri, koma zomalizazi sizingatheke popanda kuletsa kapena kupitilira malire opangira ma stacks a Bluetooth.
Zomwe zili ndi AAC ndizosamveka: kumbali imodzi, mwachidziwitso codec iyenera kutulutsa khalidwe losasiyanitsidwa ndi choyambirira, koma pochita, kuweruza ndi mayesero a labotale ya SoundGuys pazida zosiyanasiyana za Android, izi sizikutsimikiziridwa. Mwachidziwikire, vuto liri ndi ma encoder omvera amtundu wotsika kwambiri omwe amapangidwa mumitundu yosiyanasiyana yamafoni. Ndizomveka kugwiritsa ntchito AAC pazida za Apple zokha, komanso pa Android kuti muchepetse ku aptX ndi LDAC.
Zida za Hardware zomwe zimathandizira ma codec ena zimakhala zapamwamba kwambiri, chifukwa chazida zotsika mtengo kwambiri, sizomveka kulipira chiphaso cha chilolezo kuti mugwiritse ntchito ma codec amenewo. M'mayeso anga, SBC imamveka bwino kwambiri pazida zabwino.
Ndidapanga ntchito yapaintaneti yomwe imasunga mawu ku SBC, aptX ndi aptX HD munthawi yeniyeni, pasakatuli. Ndi iyo, mutha kuyesa ma codec awa osatumiza mawu kudzera pa Bluetooth, pamutu uliwonse wama waya, zokamba, ndi nyimbo zomwe mumakonda, komanso kusintha magawo amawu mukamasewera mawu:
Ntchitoyi imagwiritsa ntchito malaibulale a SBC coding kuchokera ku projekiti ya BlueZ ndi libopenaptx kuchokera ku ffmpeg, zomwe zimaphatikizidwa mu WebAssembly ndi JavaScript kuchokera ku C, kudzera pa emscripten, kuti ziyendetse mu msakatuli. Ndani angalote za tsogolo lotere!
Nazi zomwe zikuwoneka:
Onani momwe phokoso limasinthira pambuyo pa 20 kHz pama codec osiyanasiyana. Fayilo yoyambirira ya MP3 ilibe ma frequency opitilira 20 kHz.
Yesani kusintha ma codec ndikuwona ngati mukumva kusiyana pakati pa choyambirira, SBC 53 Joint Stereo (mbiri yodziwika bwino), ndi aptX/aptX HD.
Ndimamva kusiyana kwa ma codec Π ΠΠ Π Π Β° Π‘ΡΠ‘ Π Π Π ΡΠ ΡΠ Β° Π‘ ...!
Anthu omwe samamva kusiyana pakati pa ma codec pakuyesedwa kudzera pa intaneti amati amamva akamamvera nyimbo pamakutu opanda zingwe. Tsoka, izi si nthabwala kapena zotsatira za placebo: kusiyana kumamveka kwenikweni, koma sikumayambitsidwa ndi kusiyana. kodi.
Ma chipset omvera ambiri a Bluetooth omwe amagwiritsidwa ntchito pazida zolandirira opanda zingwe ali ndi Digital Signal processor (DSP), yomwe imagwiritsa ntchito chofanana, compander, stereo expander, ndi zinthu zina zomwe zimapangidwira kukonza (kapena kusintha) phokoso. Opanga zida za Bluetooth amatha kukonza DSP pa codec iliyonse padera, ndipo posinthana pakati pa ma codec, womvera angaganize kuti akumva kusiyana pakati pa machitidwe a codec, pamene kwenikweni akumvetsera ku machitidwe osiyanasiyana a DSP.
DSP Kalimba audio processing pipeline in chips opangidwa ndi CSR/Qualcomm
Yambitsani ntchito zosiyanasiyana za DSP pa codec iliyonse ndikutulutsa padera
Zida zina zamtengo wapatali zimabwera ndi mapulogalamu omwe amakulolani kuti musinthe makonda a DSP, koma mahedifoni otsika mtengo kwambiri satero, ndipo ogwiritsa ntchito sangathe kuzimitsa makina omvera pambuyo pake.
Zomwe zimagwira ntchito pazida
Mtundu wamakono wamtundu wa A2DP uli ndi "Absolute volume control" ntchito - Kuwongolera voliyumu ya chipangizocho pogwiritsa ntchito malamulo apadera a protocol ya AVRCP, yomwe imayang'anira phindu la gawo lotulutsa, m'malo mochepetsera kuchuluka kwa mawu omvera. Ngati musintha voliyumu pamakutu anu, kusinthako sikukugwirizana ndi voliyumu ya foni yanu, ndiye kuti mahedifoni anu kapena foni sizigwirizana ndi izi. Pankhaniyi, n'zomveka nthawi zonse kumvetsera nyimbo ndi voliyumu pazipita pa foni, kusintha voliyumu yeniyeni ndi mabatani chomverera m'makutu - pamenepa, chiΕ΅erengero cha chizindikiro ndi phokoso adzakhala bwino ndi khalidwe audio. ziyenera kukhala apamwamba.
Kunena zoona, pali mikhalidwe yomvetsa chisoni. Pamakutu anga a RealForce OverDrive D1 a SBC, compander yamphamvu imatsegulidwa, ndipo kuwonjezereka kwa voliyumu kumabweretsa kuwonjezeka kwa phokoso la phokoso, pamene phokoso la phokoso silimasintha (chizindikirocho chikukakamizidwa). Chifukwa cha izi, muyenera kuyika voliyumu pakompyuta mpaka theka, pomwe palibe kukakamiza.
Malinga ndi zomwe ndawonera, mahedifoni onse okhala ndi ma codec owonjezera amathandizira ntchito yowongolera voliyumu, mwachiwonekere ichi ndi chimodzi mwazofunikira pakuzindikiritsa ma codec.
Ma headphones ena amathandizira kulumikiza zipangizo ziwiri nthawi imodzi. Izi zimakupatsani mwayi, mwachitsanzo, kumvera nyimbo kuchokera pakompyuta yanu ndikulandila mafoni kuchokera pafoni yanu. Komabe, muyenera kudziwa kuti munjira iyi ma codec ena amazimitsidwa ndipo SBC yokha ndiyomwe imagwiritsidwa ntchito.
AVDTP 1.3 Kuchedwa Kufotokozera ntchito amalola mahedifoni kuti afotokoze kuchedwa kwa chipangizo chotumizira chomwe chimayimbidwa. Izi zimakupatsani mwayi wosinthira kusinthasintha kwamawu ndi kanema mukamawonera mafayilo amakanema: ngati pali zovuta pakufalitsa pawailesi, mawuwo sakhala kumbuyo kwa kanemayo, koma m'malo mwake, kanemayo amachedwetsedwa ndi wosewera mpaka zomvera ndi kanema ndi synchronized kachiwiri.
Ntchitoyi imathandizidwa ndi mahedifoni ambiri, Android 9+ ndi Linux yokhala ndi PulseAudio 12.0+. Sindikudziwa kuthandizira izi pamapulatifomu ena.
Kuyankhulana kwapawiri kudzera pa Bluetooth. Kutumiza kwa mawu.
Pakutumiza kwa mawu mu Bluetooth, Synchronous Connection Oriented (SCO) imagwiritsidwa ntchito - kufalitsa kolumikizana ndi kukambirana koyambirira kwa kulumikizana. Njirayi imakupatsani mwayi wofalitsa mawu ndi mawu mosamalitsa, ndikutumiza ndi kulandira ma symmetrical, osadikirira kutsimikiziridwa kwapaketi ndikutumizanso mapaketi. Izi zimachepetsa kuchedwa konse kwa kufalikira kwamawu pawayilesi, koma zimayika zoletsa zazikulu pa kuchuluka kwa data yomwe imatumizidwa pagawo la nthawi, ndikusokoneza mtunduwo.
Njirayi ikagwiritsidwa ntchito, mawu onse amawu ndi ma audio amafalitsidwa ndi mtundu womwewo.
Tsoka ilo, pofika chaka cha 2019, mawu abwino pa Bluetooth akadali osauka, ndipo sizikudziwika chifukwa chake Bluetooth SIG sikuchitapo kanthu.
CVSD
Codec yoyambira ya CVSD idakhazikitsidwa mu 2002, ndipo imathandizidwa ndi zida zonse zoyankhulirana za Bluetooth. Amapereka mauthenga omvera ndi mafupipafupi a 8 kHz, omwe amafanana ndi mafoni amtundu wamba.
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Zithunzi za mSBC
Ma codec owonjezera a mSBC adasinthidwa mu 2009, ndipo mu 2010 tchipisi tomwe timagwiritsa ntchito pofalitsa mawu zidawonekera kale. mSBC imathandizidwa kwambiri ndi zida zosiyanasiyana.
Iyi si codec yodziyimira payokha, koma SBC yokhazikika yochokera muyeso ya A2DP, yokhala ndi mbiri yokhazikika: 16 kHz, mono, bitpool 26.
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Osati zanzeru, koma zabwino kwambiri kuposa CVSD, komabe ndizosautsa kugwiritsa ntchito kulumikizana pa intaneti, makamaka mukamagwiritsa ntchito mahedifoni kuti mulankhule pamasewera - zomvera zamasewera zimaperekedwanso pazitsanzo za 16 kHz.
Kampani ya FastStreamCSR idaganiza zopanga lingaliro logwiritsa ntchito SBC. Kuti adutse malire a protocol ya SCO ndikugwiritsa ntchito ma bitrate apamwamba, CSR idapita njira ina - adayambitsa chithandizo chanjira ziwiri za SBC munjira imodzi yotumizira ma audio ya A2DP, mbiri yokhazikika ya encoding, ndikuyitcha "FastStream".
FastStream imatumiza mawu omvera a stereo pa 44.1 kapena 48 kHz okhala ndi bitrate ya 212 kbps kwa olankhula, ndipo mono, 16 kHz, yokhala ndi bitrate ya 72 kbps imagwiritsidwa ntchito kutumizira ma audio kuchokera pa maikolofoni (yabwinoko pang'ono kuposa mSBC). Magawo oterowo ndi oyenerera bwino kulumikizana pamasewera a pa intaneti - phokoso lamasewera ndi ophatikizana adzakhala apamwamba kwambiri.
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Kampaniyo idabwera ndi ndodo yosangalatsa, koma chifukwa chotsutsana ndi muyezo wa A2DP, imathandizidwa ndi ma transmitters ena akampani (omwe amagwira ntchito ngati khadi la audio la USB, osati chipangizo cha Bluetooth), koma sichimatero. landirani chithandizo mu stacks Bluetooth.ngakhale kuchuluka kwa mahedifoni okhala ndi FastStream thandizo sikochepa.
Pakadali pano, thandizo la FastStream mu OS ndilokha kuchokera kwa wopanga mapulogalamu Pali RohΓ‘r, yemwe sanaphatikizidwe munthambi yayikulu ya pulogalamuyi.
aptX Low Latency
Chodabwitsa ndichakuti, aptX Low Latency imathandiziranso mawu omvera, kugwiritsa ntchito mfundo yofanana ndi FastStream.
Sizingatheke kugwiritsa ntchito mbali iyi ya codec kulikonse - palibe chithandizo cha Low Latency decoding mu OS iliyonse kapena mu stack iliyonse ya Bluetooth yomwe ndikudziwa.
Bluetooth 5, Classic ndi Low Energy
Pakhala pali chisokonezo chochuluka kuzungulira mafotokozedwe a Bluetooth ndi matembenuzidwe chifukwa cha kukhalapo kwa miyezo iwiri yosagwirizana pansi pa mtundu womwewo, womwe umagwiritsidwa ntchito kwambiri pazinthu zosiyanasiyana.
Pali ma protocol awiri osiyana, osagwirizana ndi Bluetooth: Bluetooth Classic ndi Bluetooth Low Energy (LE, yomwe imadziwikanso kuti Bluetooth Smart). Palinso protocol yachitatu, Bluetooth High Speed, koma sifalikira ndipo sikugwiritsidwa ntchito pazida zapakhomo.
Kuyambira ndi Bluetooth 4.0, kusintha kwazomwe zimakhudzidwa makamaka ndi Bluetooth Low Energy, ndipo mtundu wa Classic udangowonjezera pang'ono.
Mndandanda wa zosintha pakati pa Bluetooth 4.2 ndi Bluetooth 5:
9 KUSINTHA KUCHOKERA V4.2 MPAKA 5.0
9.1 NKHANI ZATSOPANO
Zatsopano zingapo zatulutsidwa mu Bluetooth Core Specification 5.0 Release. Mbali zazikulu zowonjezeretsa ndi:
β’ Slot Availability Mask (SAM)
β’ 2 Msym/s PHY ya LE
β’LE Long Range
β’ Kutsatsa Kwapamwamba Kosalumikizidwa
β’ Zowonjezera Zotsatsa za LE
β’ LE Channel Selection Algorithm #2
9.1.1 Zowonjezeredwa mu CSA5 - Zophatikizidwa mu v5.0
β’ Mphamvu Zapamwamba Zotulutsa
Source: (Chithunzi patsamba 291)
Kusintha kumodzi kokha kunakhudza mtundu wa Classic mkati mwa dongosolo la Bluetooth 5: adawonjezera chithandizo chaukadaulo wa Slot Availability Mask (SAM), wopangidwa kuti apititse patsogolo kulekanitsa kwa wailesi. Zosintha zina zonse zimangokhudza Bluetooth LE (ndi Mphamvu Yapamwamba Yotulutsanso).
onse Zida zomvera zimagwiritsa ntchito Bluetooth Classic yokha. Ndizosatheka kulumikiza mahedifoni ndi olankhula kudzera pa Bluetooth Low Energy: palibe muyezo wotumizira ma audio pogwiritsa ntchito LE. Muyezo wa A2DP, womwe umagwiritsidwa ntchito potumiza mawu apamwamba kwambiri, umagwira ntchito kudzera pa Bluetooth Classic, ndipo palibe analogi mu LE.
Kutsiliza - kugula zida zomvera ndi Bluetooth 5 chifukwa cha mtundu watsopano wa protocol ndizopanda pake. Bluetooth 4.0/4.1/4.2 m'mawu omvera adzagwira ntchito chimodzimodzi.
Ngati kulengeza kwa mahedifoni atsopano kumatchula kuchuluka kwa magwiridwe antchito ndikuchepetsa kugwiritsa ntchito mphamvu chifukwa cha Bluetooth 5, ndiye kuti muyenera kudziwa kuti mwina sakumvetsetsa kapena akusocheretsani. Palibe zodabwitsa, chifukwa ngakhale opanga tchipisi ta Bluetooth pazolengeza zawo amasokonezeka chifukwa cha kusiyana kwa mtundu watsopano wa muyezo, ndipo tchipisi ta Bluetooth 5 timathandizira mtundu wachisanu wa LE, ndikugwiritsa ntchito 4.2 ya Classic.
Kuchedwa kufalitsa mawu
Kuchuluka kwa kuchedwa (kuchedwa) kwamawu kumatengera zinthu zambiri: kukula kwa buffer mu stack ya audio, mu stack ya Bluetooth ndi chipangizo chosewera opanda zingwe, komanso kuchedwa kwa codec.
Kuchedwa kwa ma codec osavuta monga SBC, aptX ndi aptX HD ndi ochepa kwambiri, 3-6 ms, omwe amatha kunyalanyazidwa, koma ma codec ovuta monga AAC ndi LDAC angayambitse kuchedwa koonekera. AAC algorithmic latency ya 44.1 kHz ndi 60 ms. LDAC - pafupifupi 30 ms (kutengera kusanthula mozama kwa code code. Ndikhoza kulakwitsa, koma osati zambiri.)
Zotsatira zake zimatengera kwambiri chipangizo chosewera, chipset ndi buffer. Pamayeso, ndinalandira kufalikira kwa 150 mpaka 250 ms pazida zosiyanasiyana (ndi SBC codec). Ngati tikuganiza kuti zida zomwe zimathandizira ma codec owonjezera aptX, AAC ndi LDAC zimagwiritsa ntchito zida zapamwamba komanso kakulidwe kakang'ono ka bafa, timapeza ma latency awa:
SBC: 150-250ms
aptX: 130-180 ms
AAC: 190-240 ms
LDAC: 160-210 ms
Ndiroleni ndikukumbutseni: aptX Low Latency sichimagwiritsidwa ntchito pamakina ogwiritsira ntchito, ndichifukwa chake latency yotsika imatha kupezeka ndi cholumikizira + cholandila kapena chophatikizira + mahedifoni / speaker, ndipo zida zonse ziyenera kuthandizira codec iyi.
Chipangizo cha Bluetooth, certification, ndi logo nkhani
Kodi mungasiyanitse bwanji chipangizo chamtundu wapamwamba kwambiri kuchokera ku luso lotsika mtengo? M'mawonekedwe, choyamba!
Kwa mahedifoni otsika mtengo achi China, okamba ndi olandila:
- Mawu akuti "Bluetooth" akusowa m'bokosi ndi chipangizo, "Wireless" ndi "BT" amagwiritsidwa ntchito nthawi zambiri
- Chizindikiro cha Bluetooth chikusowa pa bokosi kapena chipangizo
- Palibe buluu wonyezimira wa LED
Kusowa kwa zinthu izi kukuwonetsa kuti chipangizocho sichinatsimikizidwe, zomwe zikutanthauza kuti mwina ndi chotsika komanso chovuta. Mwachitsanzo, zomverera m'makutu za Bluedio sizovomerezeka ndi Bluetooth ndipo sizimatsatira ndondomeko ya A2DP. Iwo sakanadutsa certification.
Tiyeni tiwone zida zingapo ndi mabokosi kuchokera kwa iwo:
Izi zonse ndi zida zosatsimikizika. Malangizowo akhoza kukhala ndi logo ndi dzina laukadaulo wa Bluetooth, koma chofunikira kwambiri ndikuti ali pabokosi ndi / kapena chipangizocho.
Ngati mahedifoni kapena zokamba zanu zikuti "Ze bluetooth dewise yalumikizidwa bwino", izi sizikuwonetsanso mtundu wawo:
Pomaliza
Kodi Bluetooth ingalowe m'malo mwa mahedifoni okhala ndi mawaya ndi mahedifoni? Ndizotheka, koma pamtengo woyipa woyimba foni, kuchulukitsidwa kwa audio komwe kumatha kukwiyitsa pamasewera, komanso ma codec ambiri omwe amafunikira chindapusa ndikuwonjezera mtengo womaliza wa mafoni am'manja ndi mahedifoni.
Kutsatsa kwa ma codec ena ndikwamphamvu kwambiri: aptX ndi LDAC zimaperekedwa ngati zolowa m'malo mwa "SBC yakale komanso yoyipa", yomwe siili yoyipa monga momwe anthu amaganizira.
Monga momwe zinakhalira, malire opangira ma stacks a Bluetooth pa SBC bitrate akhoza kudumpha, kotero kuti SBC isakhale yotsika kwa aptX HD. Ndidachitapo kanthu m'manja mwanga ndikupanga chigamba cha LineageOS firmware:
Zambiri zitha kupezeka pamasamba ΠΈ .
Bonasi: . Fayiloyi inkatumizidwa poyera pa webusayiti ya Bluetooth, koma tsopano ikupezeka kwa mamembala a Bluetooth SIG okha.
Source: www.habr.com