Ma muli o ka hana nui ʻana o nā smartphones me ka ʻole o ka leo leo 3.5 mm, ua lilo nā headphone Bluetooth uea i ke ala nui no ka lehulehu e hoʻolohe i ke mele a kamaʻilio ma ke ʻano headset.
Manufacturers o ka uwea mea 'aʻole kākau mau kiko'ī kiko'ī huahana, a me 'atikala e pili ana i Bluetooth leo ma ka Internet mea contradictory, i kekahi manawa hewa, mai kamaʻilio e pili ana i nā hiʻona a pau, a pinepine kope i ka ia 'ike i ole i ka mea maoli.
E ho'āʻo kākou e hoʻomaopopo i ka protocol, nā mana o nā pūʻulu Bluetooth OS, nā headphone a me nā mea ʻōlelo, nā codec Bluetooth no ke mele a me ka haʻiʻōlelo, e ʻike i ka mea e pili ana i ka maikaʻi o ke kani i hoʻouna ʻia a me ka latency, e aʻo pehea e hōʻiliʻili a hoʻokaʻawale i ka ʻike e pili ana i nā codec kākoʻo a me nā mea hana ʻē aʻe. nā mea hiki.

Aku; DR:

• SBC - codec maʻamau
• Loaʻa i nā headphone i kā lākou equalizer a me ka hoʻoponopono hope no kēlā me kēia codec
• ʻAʻole maikaʻi ka aptX e like me ka mea i hoʻolaha ʻia
• ʻO LDAC ke kūʻai aku nei i ka bullshit
• ʻAʻole maikaʻi ka maikaʻi o ke kelepona
• Hiki iā ʻoe ke hoʻokomo i nā encoder leo C i kāu polokalamu kele pūnaewele ma ka hōʻuluʻulu ʻana iā lākou i WebAssembly ma o emscripten, a ʻaʻole lākou e lohi nui.

Mele ma o Bluetooth

Hoʻoholo ʻia ka ʻāpana hana o Bluetooth e nā profiles - nā kikoʻī o nā hana kikoʻī. Hoʻohana ka hoʻoheheʻe ʻana i nā mele Bluetooth i kahi kiʻekiʻe kiʻekiʻe A2DP unidirectional hoʻouna leo leo. Ua lawe ʻia ka maʻamau A2DP ma 2003 a ʻaʻole i loli nui mai ia manawa.
I loko o ka ʻaoʻao, 1 codec koi o ka paʻakikī helu haʻahaʻa haʻahaʻa SBC, i hana ʻia no Bluetooth, a ua hoʻohālikelike ʻia nā mea hou aʻe 3. Hiki nō hoʻi ke hoʻohana i nā codec undocumented o kāu hoʻokō ponoʻī.

ʻO Iune 2019 mākou i loko o ka xkcd comic me 14 A2DP codecs:

• SBC ← hoʻonohonoho ʻia ma A2DP, kākoʻo ʻia e nā mea hana āpau
• MPEG-1/2 Layer 1/2/3 ← hoʻohālikelike ʻia ma A2DP: ʻike ʻia MP3, hoʻohana ʻia i ka TV kikohoʻe MP2, a ʻike ʻole ʻia MP1
• MPEG-2/4 AAC ← hoʻonohonoho ʻia ma A2DP
• ATTRAC ← codec kahiko mai Sony, i hoʻopaʻa ʻia ma A2DP
• ʻO LDAC ← codec hou mai Sony
• aptX ← codec mai ka makahiki 1988
• aptXHD ← like me aptX, me nā koho hoʻopāpā ʻokoʻa wale nō
• aptX Latency Haahaa ← codec ʻokoʻa loa, ʻaʻohe hoʻokō polokalamu
• aptX Adaptive ← kekahi codec mai Qualcomm
• Aliʻi wikiwiki ← pseudo codec, hoʻololi SBC bidirectional
• HWA LHDC ← codec hou mai Huawei
• Samsung HD ← kākoʻo ʻia e nā mea hana 2
• Samsung Scalable ← kākoʻo ʻia e nā mea hana 2
• Samsung UHQ-BT ← kākoʻo ʻia e nā mea hana 3

No ke aha mākou e pono ai i nā codecs i nā mea a pau, ke nīnau nei ʻoe, i ka wā e loaʻa ai iā Bluetooth EDR, ka mea e hiki ai iā ʻoe ke hoʻoili i ka ʻikepili ma ka wikiwiki o 2 a me 3 Mbit / s, a no ka uncompressed ʻelua-kanal 16-bit PCM, 1.4 Mbit / s lawa?

Hoʻoili ʻikepili ma o Bluetooth

ʻElua ʻano o ka hoʻoili ʻikepili ma Bluetooth: Asynchronous Connection Less (ACL) no ka hoʻoili asynchronous me ka ʻole o ka hoʻokumu ʻana i ka pilina, a me Synchronous Connection Oriented (SCO), no ka hoʻoili like ʻana me ke kūkākūkā pili mua.
Lawe ʻia ka hoʻouna ʻana me ka hoʻohana ʻana i kahi papahana hoʻokaʻawale manawa a koho i kahi kaila hoʻouna no kēlā me kēia ʻeke (Frequency-Hop/Time-Division-Duplex, FH/TDD), no ka mea, ua māhele ʻia ka manawa i 625-microsecond intervals i kapa ʻia nā slots. Hoʻouna ʻia kekahi o nā mea hana ma nā slot helu like, a ʻo kekahi i nā slot helu ʻokoʻa. Hiki i ka ʻeke i hoʻouna ʻia ke noho i 1, 3 a i ʻole 5 mau slots, e pili ana i ka nui o ka ʻikepili a me ke ʻano o ka hoʻouna ʻana, i kēia hihia, lawe ʻia ka hoʻouna ʻana e hoʻokahi hāmeʻa ma nā ʻāpana like ʻole a hiki i ka hopena o ka hoʻouna ʻana. Ma ka huina, hiki ke loaʻa a hoʻouna ʻia i nā ʻeke 1600 i kēlā me kēia kekona, inā e noho kēlā me kēia o lākou i 1 slot, a hoʻouna nā mea ʻelua a loaʻa kekahi mea me ka ʻole o ka pau ʻana.

ʻO 2 a me 3 Mbit/s no EDR, hiki ke ʻike ʻia ma nā hoʻolaha a ma ka pūnaewele Bluetooth, ʻo ia ka palena kiʻekiʻe o ka hoʻololi ʻana i ke kahawai o nā ʻikepili āpau i ka huina (me nā poʻomanaʻo ʻenehana o nā protocol āpau kahi e hoʻopili ʻia ai ka ʻikepili), ma nā ʻaoʻao ʻelua. i ka manawa like. E ʻokoʻa loa ka wikiwiki o ka hoʻoili ʻikepili maoli.

No ka hoʻouna ʻana i ke mele, hoʻohana ʻia kahi ʻano asynchronous, aneane e hoʻohana mau i nā ʻeke e like me 2-DH5 a me 3-DH5, e lawe ana i ka nui o ka ʻikepili ma ke ʻano EDR o 2 Mbit/s a me 3 Mbit/s, kēlā me kēia, a noho 5 manawa. -kaʻana like.

Hōʻike kikoʻī o ka hoʻouna ʻana me ka hoʻohana ʻana i 5 mau māka e kekahi mea a me 1 slot e kekahi (DH5/DH1):


Ma muli o ke kumu o ka mahele manawa o nā nalu, koi ʻia mākou e kali i kahi manawa 625-microsecond manawa ma hope o ka hoʻouna ʻana i kahi ʻeke inā ʻaʻole lawe ka lua o nā mea i kekahi mea iā mākou a i ʻole e hoʻouna i kahi ʻeke liʻiliʻi, a ʻoi aku ka manawa inā e hoʻouna ka lua. i loko o nā ʻeke nui. Inā ʻoi aku ma mua o hoʻokahi mea i hoʻopili ʻia i ke kelepona (no ka laʻana, nā headphone, nā wati a me ke kūpeʻe kino), a laila e kaʻana like ka manawa hoʻoili ma waena o lākou āpau.

ʻO ka pono e hoʻopili i nā leo i nā protocol transport kūikawā L2CAP a me AVDTP e lawe i 16 bytes mai ka nui o ka nui o ka uku leo ​​i hoʻouna ʻia.

ʻAno pūʻolo
Ka helu o nā kau
Max. ka helu o nā bytes i loko o ka ʻeke
Max. ka helu o nā bytes o A2DP uku
Max. A2DP uku 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

ʻAʻole lawa ka 1414 a me 1429 kbps i ka hoʻouna ʻana i nā leo i hoʻopaʻa ʻole ʻia i nā kūlana maoli, me ka leo walaʻau 2.4 GHz a me ka pono e hoʻouna i ka ʻikepili lawelawe. Ke koi nei ʻo EDR 3 Mbit/s i ka mana hoʻouna a me ka walaʻau ma ka lewa, no laila, ʻoiai ma ke ʻano 3-DH5, ʻaʻole hiki ke hoʻouna ʻia ka PCM ʻoluʻolu, e mau ana nā manawa pōkole, a e hana wale nā ​​mea āpau ma kahi mamao o kahi. mau mika.
I ka hoʻomaʻamaʻa, ʻo kahi kahawai leo 990 kbit/s (LDAC 990 kbit/s) paʻakikī ke hoʻouna.

E hoʻi kāua i nā codecs.

SBC

Pono ka Codec no nā mea hana a pau e kākoʻo ana i ka maʻamau A2DP. ʻO ka codec maikaʻi loa a maikaʻi ʻole i ka manawa like.

Laʻana pinepine
Hohonu hohonu
Bitrate
Kākoʻo hoʻopāpā
Kākoʻo decoding

16, 32, 44.1, 48 kHz
16 bit
10-1500 kbps
ʻO nā mea hana a pau
ʻO nā mea hana a pau

ʻO SBC kahi codec maʻalahi a wikiwiki hoʻi, me kahi kumu hoʻohālike psychoacoustic kahiko (hoʻopili wale ʻia nā leo mālie), me ka adaptive pulse code modulation (APCM).
Manaʻo ka ʻōlelo kikoʻī A2DP i ʻelua ʻaoʻao no ka hoʻohana ʻana: Middle Quality a High Quality.


He nui nā hoʻonohonoho o ka codec e hiki ai iā ʻoe ke hoʻomalu i ka lohi algorithmic, ka helu o nā laʻana i loko o kahi poloka, ka bit distribution algorithm, akā kokoke i nā wahi āpau e hoʻohana ʻia nā ʻāpana like i ʻōlelo ʻia ma ka kikoʻī: Joint Stereo, 8 frequency bands, 16 blocks in he kiʻi leo, ke ʻano hoʻohele haʻahaʻa haʻahaʻa.
Kākoʻo ʻo SBC i ka hoʻololi ikaika ʻana o ka ʻāpana Bitpool, e pili pono ana i ka bitrate. Inā paʻa nā hawewe lewa, nalowale nā ​​ʻeke, a i ʻole nā ​​mea hana ma kahi mamao loa, hiki i ke kumu leo ​​ke hoʻemi i ka Bitpool a hiki i ka hoʻi ʻana o ke kamaʻilio maʻamau.

Hoʻonohonoho ka hapa nui o nā mea hana headphone i ka waiwai Bitpool kiʻekiʻe loa i 53, kahi e kaupalena ʻia ai ka bitrate i 328 kilobits i kekona ke hoʻohana nei i ka ʻaoʻao i ʻōlelo ʻia.
ʻOiai inā ua hoʻonohonoho ka mea hana headphone i ka waiwai Bitpool kiʻekiʻe ma luna o 53 (ʻike ʻia kēlā mau hiʻohiʻona, no ka laʻana: Beats Solo³, JBL Everest Elite 750NC, Apple AirPods, loaʻa pū kekahi ma kekahi mau mea hoʻokipa a me nā ʻāpana poʻo kaʻa), a laila ʻaʻole ʻae ka hapa nui o OS. ka hoʻohana ʻana i nā bitrates i hoʻonui ʻia ma muli o ka hoʻonohonoho ʻana i ka palena waiwai kūloko i nā pūʻulu Bluetooth.
Hoʻohui hou, hoʻonohonoho kekahi mau mea hana i ka waiwai Bitpool kiʻekiʻe i haʻahaʻa no kekahi mau mea hana. No ka laʻana, no Bluedio T ʻo ia ka 39, no Samsung Gear IconX ʻo ia ka 37, e hāʻawi ana i ka maikaʻi leo maikaʻi ʻole.

ʻO nā mea paʻa i hana ʻia ma ka ʻaoʻao o nā mea hoʻomohala o nā pūʻulu Bluetooth i kū mai ma muli o ka like ʻole o kekahi mau mea me nā waiwai Bitpool nui a i ʻole atypical profiles, ʻoiai inā hōʻike lākou i ke kākoʻo no lākou, a ʻaʻole lawa ka hoʻāʻo ʻana i ka wā hōʻoia. ʻOi aku ka maʻalahi o nā mea kākau o Bluetooth stacks e kaupalena iā lākou iho i ka ʻae ʻana i ka ʻaoʻao i ʻōlelo ʻia, ma mua o ka hoʻokumu ʻana i nā ʻikepili o nā mea hana hewa (ʻoiai ke hana nei lākou i kēia no nā hana hana hewa ʻole).

Hoʻokaʻawale ikaika ʻo SBC i nā bit quantization i nā alapine ma ke kumu haʻahaʻa a kiʻekiʻe, me nā kaupaona ʻokoʻa. Inā hoʻohana ʻia ka bitrate a pau no nā alapine haʻahaʻa a me waena, e "ʻoki ʻia" nā alapine kiʻekiʻe (ʻo ia ka hāmau).

Laʻana SBC 328 kbps. Aia ma luna ka mea kumu, ma lalo ka SBC, e hoʻololi pinepine ana ma waena o nā mele. Ke hoʻohana nei ka leo i ka waihona wikiō i ka FLAC lossless compression codec. ʻAʻole hoʻohana ʻia ka hoʻohana ʻana i ka FLAC i loko o kahi pahu mp4, no laila ʻaʻole i hōʻoiaʻiʻo ʻia e pāʻani kāu polokalamu kele pūnaewele, akā pono ia e hana i nā mana hou loa o ka desktop Chrome a me Firefox. Inā ʻaʻohe kani, hiki iā ʻoe ke hoʻoiho i ka faila a wehe iā ia i loko o kahi mea pāʻani wikiō piha.
ZZ Top - Kanaka ʻaʻahu ʻaʻahu

Hōʻike ka spectrogram i ka manawa o ka hoʻololi ʻana: ʻoki ʻo SBC i nā leo mālie ma luna o 17.5 kHz, a ʻaʻole e hoʻokaʻawale i nā bits no ka hui ma luna o 20 kHz. Loaʻa ka spectrogram piha ma ke kaomi ʻana (1.7 MB).

ʻAʻole au i lohe i kekahi ʻokoʻa ma waena o ka mea kumu a me SBC ma kēia ala.

E lawe i kahi mea hou a hoʻohālike i ka leo e loaʻa me ka hoʻohana ʻana i nā headphone Samsung Gear IconX me Bitpool 37 (ma luna - ka hōʻailona kumu, ma lalo - SBC 239 kbps, leo ma FLAC).
ʻO ka manaʻo hoʻomāʻewaʻewa - Hoʻike

Lohe au i ka pahū ʻana, ka liʻiliʻi o ka stereo a me ka leo "clunking" maikaʻi ʻole i nā alapine kiʻekiʻe o nā leo.

ʻOiai he codec maʻalahi loa ʻo SBC, hiki ke hoʻonohonoho ʻia no ka latency haʻahaʻa, hāʻawi i ka maikaʻi leo maikaʻi loa i nā bitrates kiʻekiʻe (452+ kbps) a maikaʻi loa no ka hapa nui o nā poʻe ma ke ʻano High Quality (328 kbps), ma muli o kēlā. ʻAʻole hōʻike ka maʻamau A2DP i nā profile paʻa (akā hāʻawi wale i nā ʻōlelo aʻoaʻo), ua hoʻonohonoho nā mea hoʻomohala stack i nā palena kūlohelohe ma Bitpool, ʻaʻole i hōʻike ʻia nā ʻāpana o ka leo i hoʻouna ʻia ma ka interface mea hoʻohana, a me nā mea hana headphone e hoʻonohonoho i kā lākou mau hoʻonohonoho ponoʻī a ʻaʻole loa. hōʻike i ka waiwai Bitpool i nā kikoʻī ʻenehana o ka huahana, ua lilo ka codec i kaulana no kona ʻano haʻahaʻa haʻahaʻa, ʻoiai ʻaʻole kēia he pilikia me ka codec e like me ia.
Hoʻopili pololei ka ʻāpana Bitpool i ka bitrate i loko o hoʻokahi ʻaoʻao. Hiki i ka Bitpool 53 waiwai ke hāʻawi i ka bitrate o 328 kbps me ka ʻōlelo kiʻekiʻe kiʻekiʻe i manaʻo ʻia, a me 1212 kbps me Dual Channel a me 4 mau alapine, ʻo ia ke kumu o nā mea kākau OS, ma ka hoʻohui ʻana i nā kapu ma Bitpool, kau palena a ma luna. Bitrate. E like me kaʻu e ʻike ai, ua kū mai kēia kūlana ma muli o kahi hemahema o ka maʻamau A2DP: pono e kūkākūkā i ka bitrate, ʻaʻole ʻo Bitpool.

Papa papa o ke kākoʻo no nā mana SBC ma nā OS like ʻole:

Kaukau
Kākoʻo ʻia nā helu laʻana
Ka palena max. Bitpool
Ka palena max. Bitrate
Kaʻawelike maʻamau
Bitpool hoʻololi hoʻololi

Windows 10
44.1 ā
53
512 kbps
328 kbps
✓*

Linux (BlueZ + PulseAudio)
16, 32, 44.1, 48 kHz
64 (no nā pilina e komo mai ana), 53 (no nā pilina i waho)
ʻAʻohe palena
328 kbps
✓*

macOS High Sierra
44.1 ā
64, paʻamau 53***
ʻAʻohe maopopo
328 kbps
✗

Android 4.4-9
44.1/48 kHz**
53
328 kbps
328 kbps
✗

Android 4.1-4.3.1
44.1, 48 kHz**
53
229 kbps
229 kbps
✗

Blackberry OS 10
48 ā
53
ʻAʻohe palena
328 kbps
✗

* Hoʻemi wale ʻo Bitpool, akā ʻaʻole e hoʻonui maʻalahi, inā maikaʻi nā kūlana hoʻoili. No ka hoʻihoʻi ʻana iā Bitpool pono ʻoe e hoʻōki i ka pāʻani, kali i ʻelua mau kekona a hoʻomaka hou i ka leo.
** ʻO ka waiwai paʻamau e pili ana i nā hoʻonohonoho hoʻonohonoho i kuhikuhi ʻia i ka wā e hōʻuluʻulu ai i ka firmware. Ma ka Android 8/8.1 ka alapine he 44.1 kHz a i ʻole 48 kHz wale nō, e pili ana i nā hoʻonohonoho i ka wā o ka hōʻuluʻulu ʻana, ma nā ʻano ʻē aʻe 44.1 kHz a me 48 kHz i kākoʻo ʻia i ka manawa like.
*** Hiki ke hoʻonui ʻia ka waiwai Bitpool ma ka polokalamu Bluetooth Explorer.

aptX a me aptX HD

ʻO aptX kahi codec maʻalahi a wikiwiki hoʻi, me ka ʻole o psychoacoustics, me ka hoʻohana ʻana i ka modulation pulse code modulation adaptive (ADPCM). Hōʻike ʻia ma kahi o 1988 (lā waiho ʻana Palapala Sila Nui i hoʻopaʻa ʻia ma Pepeluali 1988), ma mua o ka Bluetooth, ua hoʻohana mua ʻia i nā lako leo uila uila. Loaʻa iā Qualcomm i kēia manawa, koi i ka laikini a me nā royalties. Mai ka makahiki 2014: $6000 i hoʻokahi manawa a ≈$1 no kēlā me kēia mea, no nā pūʻulu a hiki i 10000 mau mea hana (kumu, ka p. 16).
ʻO ka aptX a me ka aptX HD ka codec like, me nā ʻaoʻao hoʻopaʻa inoa like ʻole.

Hoʻokahi wale nō ʻāpana o ka codec - ke koho ʻana i ke alapine sampling. Aia nō naʻe ke koho o ka helu/ʻano o nā kaha, akā ma nā mea hana a pau i ʻike iaʻu (70+ mau ʻāpana) ʻo Stereo wale nō ke kākoʻo ʻia.

Codec
Laʻana pinepine
Hohonu hohonu
Bitrate
Kākoʻo hoʻopāpā
Kākoʻo decoding

aptX
16, 32, 44.1, 48 kHz
16 bit
128 / 256 / 352 / 384 kbps (ma muli o ka helu hōʻailona)
Windows 10 (desktop and mobile), macOS, Android 4.4+/7*, Blackberry OS 10
Ka laula nui o na mea leo (mea paahana)

* Pono nā mana a hiki i ka 7 ke hoʻololi i ka waihona Bluetooth. Kākoʻo ʻia ka codec inā ua laikini ka mea hana kelepona Android i ka codec mai Qualcomm (inā loaʻa i ka OS nā hale waihona puke).

Hoʻokaʻawale ʻo aptX i ka leo i 4 mau alapinepine a hoʻonui iā lākou me ka helu like o nā bits mau: 8 bits no 0-5.5 kHz, 4 bits no 5.5-11 kHz, 2 bits no 11-16.5 kHz, 2 bits no 16.5-22 kHz ( kiʻi no ka laʻana 44.1 kHz).

Ka laʻana o ka leo aptX (ma luna - ka hōʻailona kumu, ma lalo - aptX, spectrograms o nā ala hema wale nō, kani ma FLAC):

Ua ʻulaʻula iki nā kiʻekiʻe, akā ʻaʻole hiki iā ʻoe ke lohe i ka ʻokoʻa.

Ma muli o ka hāʻawi paʻa ʻana o nā bit quantization, ʻaʻole hiki i ke codec ke "hoʻololi i nā bits" i nā alapine e pono ai lākou. ʻAʻole like me SBC, ʻaʻole e "ʻoki" ʻo aptX i nā alapine, akā e hoʻohui i ka leo quantization iā lākou, e hōʻemi ana i ka nui o ka leo.

ʻAʻole pono e manaʻo ʻia ʻo ka hoʻohana ʻana, no ka laʻana, ʻo 2 bits i kēlā me kēia hui e hōʻemi i ka laulā dynamic i 12 dB: ADPCM hiki i ka 96 dB o ka laulā dynamic ʻoiai ke hoʻohana ʻana i 2 quantization bits, akā no kahi hōʻailona wale nō.
Mālama ʻo ADPCM i ka ʻokoʻa helu ma waena o ka laʻana o kēia manawa a me ka laʻana aʻe, ma kahi o ka mālama ʻana i ka waiwai piha e like me ka PCM. ʻAe kēia iā ʻoe e hōʻemi i nā koi no ka helu o nā bits e pono ai e mālama i ka ʻike like (me ka ʻole o ka nalowale) a i ʻole ka ʻike like (me kahi hapa pōʻai liʻiliʻi). No ka hōʻemi ʻana i nā hewa pōʻai, hoʻohana ʻia nā pākaukau coefficient.
I ka hana ʻana i ka codec, ua helu nā mea kākau i nā coefficients ADPCM ma kahi hoʻonohonoho o nā faila leo mele. ʻO ka hoʻokokoke ʻana o ka hōʻailona leo i ka hoʻonohonoho mele i kūkulu ʻia ai nā papa ʻaina, ʻoi aku ka liʻiliʻi o nā hewa quantization (noise) aptX e hana ai.

Ma muli o kēia, ʻoi aku ka maikaʻi o nā hoʻokolohua synthetic ma mua o ke mele. Ua hana au i kahi laʻana synthetic kūikawā kahi e hōʻike ai aptX i nā hopena maikaʻi ʻole - he hawewe sine me ke alapine o 12.4 kHz (ma luna - ka hōʻailona kumu, ma lalo - aptX. Audio ma FLAC. E hoʻohaʻahaʻa i ka leo!):

Kiʻi kikoʻī:


Hiki ke lohe ʻia nā walaʻau.

Eia nō naʻe, inā e hana ʻoe i kahi hawewe sine me kahi amplitude liʻiliʻi i ʻoi aku ka mālie, e ʻoi aku ka mālie o ka walaʻau, e hōʻike ana i kahi ākea ākea:

No ka lohe ʻana i ka ʻokoʻa ma waena o ke mele mele kumu a me ka mele i hoʻopaʻa ʻia, hiki iā ʻoe ke hoʻohuli i kekahi o nā hōʻailona a hoʻohui i nā ala mele ma ke kahawai. ʻO kēia ala, ma ka laulā, hewa, a ʻaʻole ia e hāʻawi i nā hopena kūpono me nā codec paʻakikī, akā no ka ADPCM ua kūpono loa ia.
Ka ʻokoʻa ma waena o ke kumu a me ka aptX
Aia ke kumu o ka ʻokoʻa huinahā like o nā hōʻailona ma ke kiʻekiʻe o -37.4 dB, ʻaʻole nui ia no ia mele i hoʻopaʻa ʻia.

aptXHD

ʻAʻole ʻo ka aptX HD he codec kūʻokoʻa - he ʻano hoʻopāʻālua i hoʻomaikaʻi ʻia o ka codec aptX. Hoʻololi nā hoʻololi i ka helu o nā bits i hoʻokaʻawale ʻia no ka hoʻopili ʻana i nā pae alapine: 10 mau bits no 0-5.5 kHz, 6 mau bits no 5.5-11 kHz, 4 mau bits no 11-16.5 kHz, 4 bits no 16.5-22 kHz (helu no 44.1 kHz) .

Codec
Laʻana pinepine
Hohonu hohonu
Bitrate
Kākoʻo hoʻopāpā
Kākoʻo decoding

aptXHD
16, 32, 44.1, 48 kHz
24 bits
192 / 384 / 529 / 576 kbps (ma muli o ka helu hōʻailona)
Android 8++
Kekahi mau leo ​​leo (mea paʻakikī)

* Pono nā mana a hiki i ka 7 ke hoʻololi i ka waihona Bluetooth. Kākoʻo ʻia ka codec inā ua laikini ka mea hana kelepona Android i ka codec mai Qualcomm (inā loaʻa i ka OS nā hale waihona puke).

ʻOi aku ka liʻiliʻi ma mua o ka aptX: pono e koi i ka laikini kaʻawale mai Qualcomm, a me nā uku laikini kaʻawale.

E hana hou i ka laʻana me ka hawewe sine ma 12.4 kHz:


ʻOi aku ka maikaʻi ma mua o ka aptX, akā naʻe ʻoi aku ka walaʻau.

aptX Latency Haahaa

He codec mai Qualcomm ʻaʻohe mea like me ka aptX maʻamau a me ka aptX HD, e hoʻoholo ana i ka ʻike liʻiliʻi mai ka poʻe i komo i kāna hoʻomohala ʻana. Hoʻolālā ʻia no ka hoʻoili leo haʻahaʻa haʻahaʻa haʻahaʻa haʻahaʻa (nā kiʻiʻoniʻoni, nā pāʻani), kahi hiki ʻole ke hoʻoponopono ʻia ka lohi leo e nā polokalamu. ʻAʻohe mea i ʻike ʻia nā polokalamu hoʻokō o nā encoders a me nā decoders; kākoʻo wale ʻia lākou e nā transmitters, receivers, headphones and speakers, akā ʻaʻole na nā smartphones a me nā kamepiula.

Laʻana pinepine
Bitrate
Kākoʻo hoʻopāpā
Kākoʻo decoding

44.1 ā
276/420 kbps
ʻO kekahi mau mea hoʻouna (mea paʻahana)
Kekahi mau leo ​​leo (mea paʻakikī)

AAC

ʻO AAC, a i ʻole Advanced Audio Coding, he codec computationally complex me kahi kumu hoʻohālike psychoacoustic koʻikoʻi. Hoʻohana nui ʻia no ka leo ma ka Pūnaewele, ka lua o ka kaulana ma hope o MP3. Koi i ka laikini a me nā uku aliʻi: $15000 i hoʻokahi manawa (a i ʻole $1000 no nā hui me ka liʻiliʻi o 15 mau limahana) + $0.98 no nā mea hana 500000 mua (kumu).
Hoʻonohonoho ʻia ka codec i loko o nā kikoʻī MPEG-2 a me MPEG-4, a kūʻē i ka manaʻo kuhihewa maʻamau, ʻaʻole ia no Apple.

Laʻana pinepine
Bitrate
Kākoʻo hoʻopāpā
Kākoʻo decoding

8 - 96 kHz
8 - 576 kbps (no ka stereo), 256 - 320 kbps (maʻamau no Bluetooth)
macOS, Android 7++, iOS
Ka laula nui o na mea leo (mea paahana)

* ma nā polokalamu wale nō i uku nā mea hana i nā uku laikini

Hoʻohana ʻo iOS a me macOS i kā Apple encoder AAC maikaʻi loa i kēia manawa e hoʻopuka i ka leo leo kiʻekiʻe loa. Hoʻohana ʻo Android i ka lua kiʻekiʻe kiʻekiʻe Fraunhofer FDK AAC encoder, akā hiki ke hoʻohana i nā lako like ʻole i kūkulu ʻia i loko o ka paepae (SoC) me ka maikaʻi hoʻopāpā ʻike ʻole. Wahi a nā hoʻokolohua hou ma ka pūnaewele SoundGuys, ʻokoʻa loa ka maikaʻi hoʻopāpā AAC o nā kelepona Android like ʻole:

ʻO ka hapa nui o nā leo leo uila ʻole he 320 kbps no ka AAC, kākoʻo kekahi i 256 kbps. Kakaʻikahi loa nā bitrates ʻē aʻe.
Hāʻawi ʻo AAC i ka maikaʻi maikaʻi ma 320 a me 256 kbps bitrates, akā pili ia ka nalowale o ka hoʻopili ʻana o ka maʻiʻo i hoʻopili mua ʻia, akā naʻe, paʻakikī ke lohe i nā ʻokoʻa me ka mea kumu ma IOS ma ka bitrate o 256 kbps me ka nui o nā hoʻopili ʻana, me ka hoʻopili hoʻokahi, no ka laʻana, MP3 320 kbps i AAC 256 kbps, hiki ke mālama ʻia nā poho.
E like me nā codec Bluetooth ʻē aʻe, hoʻokaʻawale mua ʻia kekahi mele a laila hoʻopili ʻia e ke codec. I ka hoʻolohe ʻana i ke mele ma ke ʻano AAC, ua unuhi mua ʻia e ka OS, a laila hoʻopili hou ʻia i AAC no ka hoʻouna ʻana ma o Bluetooth. Pono kēia no ka hui ʻana i nā kahawai leo he nui, e like me ke mele a me nā leka hoʻomaopopo hou. ʻAʻole ʻokoʻa ʻo iOS. Ma ka Pūnaewele hiki iā ʻoe ke ʻike i nā ʻōlelo he nui ʻaʻole i unuhi ʻia ke mele ma iOS ma ka format AAC ke hoʻouna ʻia ma o Bluetooth, ʻaʻole ia he ʻoiaʻiʻo.

MP1/2/3

Aia nā codec o ka ʻohana MPEG-1/2 Part 3 i ka MP3 kaulana a hoʻohana nui ʻia, ka MP2 liʻiliʻi loa (hoʻohana nui ʻia i ka TV kikohoʻe a me ka lekiō), a me ka MP1 ʻike ʻole loa.

ʻAʻole kākoʻo ʻia nā codecs MP1 a me MP2 kahiko: ʻAʻole hiki iaʻu ke loaʻa i nā headphone a i ʻole nā ​​pūʻulu Bluetooth e hoʻopili a hoʻololi paha iā lākou.
Kākoʻo ʻia ʻo MP3 decoding e kekahi mau headphone, akā ʻaʻole kākoʻo ʻia ka hoʻopili ʻana ma nā ʻōnaehana hana hou. Me he mea lā hiki i ka ʻaoʻao ʻekolu ʻo BlueSoleil stack no Windows ke hoʻopili i ka MP3 inā hoʻololi lima ʻoe i ka faila hoʻonohonoho, akā noʻu ke kau ʻana iā ia e alakaʻi iā BSoD ma Windows 10. Ka hopena - ʻaʻole hiki ke hoʻohana ʻia ke codec no ka leo Bluetooth.
Ma mua, ma 2006-2008, ma mua o ka hoʻolaha ʻana o ka maʻamau A2DP i nā polokalamu, hoʻolohe nā kānaka i nā mele MP3 ma ka headset Nokia BH-501 ma o ka polokalamu MSI BluePlayer, i loaʻa ma Symbian a me Windows Mobile. I kēlā manawa, ua ʻae ka ʻōnaehana OS o nā smartphones i ke komo ʻana i nā hana haʻahaʻa haʻahaʻa, a ma Windows Mobile ua hiki ke hoʻokomo i nā pūʻulu Bluetooth ʻaoʻao ʻekolu.

Ua pau ka patent hope loa o ka codec MP3; ʻaʻole koi ka hoʻohana ʻana i ka codec i nā uku laikini mai ʻApelila 23, 2017.

Inā lawe ʻia ka patent lōʻihi loa i ʻōlelo ʻia ma nā kuhikuhi i ʻōlelo ʻia ma ke ʻano he ana, a laila lilo ka ʻenehana MP3 i ka patent-free ma ʻAmelika Hui Pū ʻIa ma ʻApelila 16, 2017 i ka wā i pau ai ka US Patent 6,009,399, i paʻa a lawelawe ʻia e Technicolor.

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

Laʻana pinepine
Bitrate
Kākoʻo hoʻopāpā
Kākoʻo decoding

16 - 48 kHz
8 - 320 kbps
ʻAʻole i kākoʻo ʻia ma nā wahi āpau
Kekahi mau leo ​​leo (mea paʻakikī)

ʻO LDAC

He codec hou a hoʻoikaika ikaika ʻia ʻo "Hi-Res" mai Sony, e kākoʻo ana i nā helu hoʻohālike a hiki i 96 kHz a me 24-bit bitrate, me nā bitrates a hiki i 990 kbps. Hoʻolaha ʻia ʻo ia ma ke ʻano he codec audiophile, ma ke ʻano he pani no nā codec Bluetooth e kū nei. Loaʻa iā ia ka hana o ka hoʻoponopono bitrate adaptive, e pili ana i nā kūlana hoʻolaha lekiō.

LDAC encoder (lildac) ua hoʻokomo ʻia i loko o ka pūʻolo Android maʻamau, no laila ua kākoʻo ʻia ka hoʻopili ʻana ma kekahi kelepona Android e hoʻomaka ana me ka mana OS 8. ʻAʻole loaʻa nā polokalamu decoders manuahi, ʻaʻole i loaʻa ka kikoʻī codec i ka lehulehu, akā naʻe, i ka nānā mua ʻana i ka encoder, ua like ke ʻano o loko o ka codec. ATRAC9 - Hoʻohana ʻia ka codec a Sony ma PlayStation 4 a me Vita: hana ʻelua i ka domain frequency, hoʻohana i ka discrete cosine transform (MDCT) i hoʻololi ʻia a me ke kaomi ʻana me ka Huffman algorithm.

Hāʻawi ʻia ke kākoʻo LDAC e nā headphones mai Sony. Loaʻa ka hiki ke hoʻokaʻawale i ka LDAC i kekahi manawa ma nā headphone a me nā DAC mai nā mea hana ʻē aʻe, akā kakaikahi loa.

Laʻana pinepine
Bitrate
Kākoʻo hoʻopāpā
Kākoʻo decoding

44.1 - 96 kHz
303/606/909 kbit/s (no 44.1 a me 88.2 kHz), 330/660/990 kbit/s (no 48 a me 96 kHz)
Android 8 +
ʻO kekahi mau headphone Sony a me kekahi mau mea hana mai nā mea hana ʻē aʻe (mea paʻahana)

Hoʻopilikia ʻo Marketing LDAC ma ke ʻano he codec Hi-Res i kāna ʻenehana ʻenehana: he mea lapuwale ke hoʻolilo i ka bitrate ma ka hoʻouna ʻana i nā alapine hiki ʻole ke lohe ʻia i ka pepeiao o ke kanaka a hoʻonui i ka hohonu bit, ʻoiai ʻaʻole lawa ka hoʻouna ʻana i ka maikaʻi CD (44.1/16) me ka pohō ʻole. . ʻO ka mea pōmaikaʻi, ʻelua mau ʻano hana o ka codec: ka hoʻoili leo CD a me ka hoʻouna leo Hi-Res. I ka hihia mua, ʻo 44.1 kHz/16 bits wale nō i hoʻouna ʻia ma luna o ka lewa.

No ka mea, ʻaʻole i loaʻa manuahi ka polokalamu LDAC decoder, ʻaʻole hiki ke hoʻāʻo i ka codec me ka ʻole o nā polokalamu ʻē aʻe e wehe i ka LDAC. E like me nā hopena o ka hoʻāʻo LDAC ma kahi DAC me kāna kākoʻo, kahi i hoʻopili ʻia e nā ʻenekini SoundGuys.com ma o kahi puka kikohoʻe a hoʻopaʻa i ka leo hoʻopuka ma nā hōʻailona hoʻāʻo, LDAC 660 a me 990 kbps ma ke ʻano CD-quality mode e hāʻawi i kahi hōʻailona-i- ʻoi aku ka maikaʻi ma mua o ka aptX HD.

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

Kākoʻo pū ʻo LDAC i nā bitrates ikaika ma waho o nā moʻolelo i hoʻokumu ʻia - mai 138 kbps a 990 kbps, akā e like me kaʻu e haʻi aku ai, hoʻohana wale ʻo Android i nā profiles standardized 303/606/909 a me 330/660/990 kbps.

Nā codec ʻē aʻe

ʻAʻole hoʻohana nui ʻia nā codec A2DP ʻē aʻe. ʻO kā lākou kākoʻo ʻaneʻane pau ʻole a loaʻa paha ma kekahi mau hiʻohiʻona o nā headphone a me nā smartphones.
ʻAʻole i hoʻohana ʻia ka codec ATRAC i hoʻopaʻa ʻia ma A2DP ma ke ʻano he codec Bluetooth ʻoiai ʻo Sony ponoʻī, Samsung HD, Samsung Scalable a me Samsung UHQ-BT codecs i kākoʻo liʻiliʻi loa mai ka hoʻouna ʻana a me ka loaʻa ʻana o nā polokalamu, a he mea hou loa ʻo HWA LHDC a kākoʻo wale ʻia ʻekolu. (?) mea hana.

Kākoʻo codec no nā mea kani

ʻAʻole nā ​​mea hana a pau e hoʻopuka i ka ʻike pololei e pili ana i nā codecs i kākoʻo ʻia e kekahi mau headphone uea ʻole, nā mea ʻōlelo, nā mea hoʻokipa a i ʻole nā ​​​​mea hoʻouna. I kekahi manawa, ʻo ke kākoʻo no kekahi codec wale nō no ka hoʻouna ʻana, akā ʻaʻole no ka hoʻokipa (pili no nā transmitters-receivers i hui pū ʻia), ʻoiai ke haʻi wale nei ka mea hana i "kākoʻo", me ka ʻole o nā memo (manaʻo wau ʻo ka laikini kaʻawale o nā encoders a me nā decoders o kekahi ʻO nā codec ka hewa no kēia). Ma nā polokalamu liʻiliʻi loa, ʻaʻole paha ʻoe e ʻike i ke kākoʻo aptX i haʻi ʻia.

ʻO ka mea pōʻino, ʻaʻole hōʻike nā interface o ka hapa nui o nā ʻōnaehana hana i ka codec i hoʻohana ʻia ma nā wahi āpau. Loaʻa ka ʻike e pili ana i kēia ma Android, e hoʻomaka ana mai ka mana 8, a me macOS. Eia naʻe, i loko o kēia mau OS, ʻo kēlā mau codec wale nō i kākoʻo ʻia e ke kelepona/kamepiula a me nā headphone e hōʻike ʻia.

Pehea ʻoe e ʻike ai i nā codec i kākoʻo ʻia e kāu kelepona? E hoʻopaʻa a hoʻopaʻa i ka hoʻokuʻu ʻana i nā kaʻa me nā ʻāpana kūkākūkā A2DP!
Hiki ke hana i kēia ma Linux, macOS a me Android. Ma Linux hiki iā ʻoe ke hoʻohana iā Wireshark a i ʻole hcidump, ma macOS hiki iā ʻoe ke hoʻohana i ka Bluetooth Explorer, a ma ka Android hiki iā ʻoe ke hoʻohana i ka hana hoʻopakele ʻo Bluetooth HCI dump, i loaʻa i nā mea hoʻomohala. E loaʻa iā ʻoe kahi dump ma ka format btsnoop, hiki ke hoʻouka ʻia i loko o ka Wireshark analyzer.
E hoʻolohe: hiki ke loaʻa i kahi hoʻolei kūpono ma ka hoʻopili ʻana mai kāu kelepona/kamepiula i nā headphone/speakers (ʻaʻohe mea ʻakaʻaka paha ke kani ʻana)! Hiki i nā headphone ke hoʻokumu i kahi pilina me ke kelepona, a laila e noi lākou i kahi papa inoa o nā codecs mai ke kelepona, ʻaʻole hoʻi. No ka hōʻoia ʻana i ka hoʻopaʻa ʻia ʻana o ka hoʻolei pololei, wehe mua i ka mea hana a laila hoʻopaʻa i kāu kelepona me nā poʻo poʻo i ka wā e hoʻopaʻa ana i ka dump.

E hoʻohana i kēia kānana hōʻike e kānana i nā kaʻa pili ʻole:

btavdtp.signal_id

ʻO ka hopena, pono ʻoe e ʻike i kahi mea like me kēia:

Hiki iā ʻoe ke kaomi i kēlā me kēia mea ma ke kauoha GetCapabilities e nānā i nā kikoʻī kikoʻī o ke codec.

ʻAʻole ʻike ʻo Wireshark i nā mea hōʻike codec āpau, no laila pono e hoʻokaʻawale ʻia kekahi mau codecs me ka lima, e nānā ana i ka papa ʻike ma lalo.

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

I ʻole e nānā pono i nā dumps me ka lima, ua hana wau i kahi lawelawe e hoʻopaʻa maʻalahi i nā mea āpau: btcodecs.valdikss.org.ru

Hoʻohālikelike o nā codecs. ʻO wai ka codec ʻoi aku ka maikaʻi?

Loaʻa i kēlā me kēia codec kona mau pono a me nā hemahema.
Hoʻohana ʻo aptX a me aptX HD i nā ʻaoʻao paʻakikī i hiki ʻole ke hoʻololi ʻia me ka ʻole o ka hoʻololi ʻana i ka encoder a me ka decoder. ʻAʻole hiki i ka mea hana kelepona a i ʻole ka mea hana headphone ke hoʻololi i nā kumu hoʻopili bitrate a i ʻole aptX. Hāʻawi ka mea nona ka codec, Qualcomm, i kahi encoder kuhikuhi ma ke ʻano o kahi waihona. ʻO kēia mau ʻoiaʻiʻo ka ikaika o aptX - ʻike mua ʻoe i ke ʻano o ke kani āu e loaʻa ai, me ka ʻole o nā "akā".

ʻO SBC, ʻokoʻa, he nui nā ʻāpana configurable, dynamic bitrate (hiki i ka encoder ke hōʻemi i ka ʻāpana bitpool inā paʻa nā ea), a ʻaʻohe ona profile paʻakikī, ʻo ka "medium quality" a me ka "high quality" i ʻōlelo ʻia. i hoʻohui ʻia i ka kikoʻī A2DP ma 2003 makahiki. ʻAʻole ʻoi aku ka kiʻekiʻe o ka "kiʻekiʻe kiʻekiʻe" e nā kūlana hou, a ʻaʻole ʻae ka hapa nui o nā pūʻulu Bluetooth iā ʻoe e hoʻohana i nā ʻāpana ʻoi aku ka maikaʻi ma mua o ka "kiʻekiʻe kiʻekiʻe" profile, ʻoiai ʻaʻohe palena ʻenehana no kēia.
ʻAʻole loaʻa iā Bluetooth SIG kahi encoder SBC ma ke ʻano he waihona, a hoʻokō nā mea hana iā lākou iho.
ʻO kēia nā nāwaliwali o SBC - ʻaʻole maopopo i ka maikaʻi o ke kani e manaʻo ʻia mai kahi hāmeʻa. Hiki iā SBC ke hana i nā leo haʻahaʻa haʻahaʻa a kiʻekiʻe loa, akā ʻaʻole hiki ke loaʻa ka mea hope me ka ʻole o ka hoʻopau ʻana a i ʻole ke kāpae ʻana i nā palena hana o nā pūʻulu Bluetooth.

ʻO ke kūlana me AAC he mea kānalua: ma kekahiʻaoʻao, pono ka codec e hoʻopuka i ka maikaʻi iʻikeʻoleʻia mai ka mea mua, akā i ka hoʻomaʻamaʻaʻana, e hoʻoholo ana i nā ho'āʻo o ka SoundGuys laboratory ma nā polokalamu Android likeʻole,ʻaʻole i hōʻoia kēia. ʻO ka mea nui, aia ka hewa me nā encoder leo haʻahaʻa haʻahaʻa i kūkulu ʻia i loko o nā chipset kelepona like ʻole. Maikaʻi ka hoʻohana ʻana i ka AAC ma nā polokalamu Apple wale nō, a ma ka Android e kaupalena iā aptX a me LDAC.

ʻOi aku ka maikaʻi o nā lako paʻa e kākoʻo ana i nā codec ʻē aʻe, no ka mea, ʻaʻole kūpono ke uku ʻana i nā uku laikini no ka hoʻohana ʻana i kēlā mau codec. I kaʻu mau hoʻāʻo ʻana, kani maikaʻi loa ʻo SBC i nā lako pono.

Ua hana au i kahi lawelawe pūnaewele e hoʻopili i ka leo iā SBC, aptX a me aptX HD i ka manawa maoli, pololei ma ka polokalamu kele pūnaewele. Me ia, hiki iā ʻoe ke hoʻāʻo i kēia mau codec leo me ka ʻole o ka hoʻouna ʻana i ka leo ma o Bluetooth, ma nā headphone uea, nā mea haʻiʻōlelo, a me kāu mele punahele, a hoʻololi pū i nā ʻāpana hoʻopili pololei i ka wā e pāʻani ana i ka leo:
btcodecs.valdikss.org.ru/sbc-encoder
Hoʻohana ka lawelawe i nā hale waihona puke coding SBC mai ka papahana BlueZ a me libopenaptx mai ffmpeg, i hui pū ʻia i WebAssembly a me JavaScript mai C, ma o emscripten, e holo i ka polokalamu kele pūnaewele. ʻO wai ka mea hiki ke moeʻuhane i ka wā e hiki mai ana!

Eia he mea like e like me kēia:

E nānā i ka loli ʻana o ka pae walaʻau ma hope o 20 kHz no nā codec like ʻole. ʻAʻole i loaʻa i ka faila MP3 kumu nā alapine ma luna o 20 kHz.

E ho'āʻo e hoʻololi i nā codec a ʻike inā lohe ʻoe i ka ʻokoʻa ma waena o ka mea kumu, SBC 53 Joint Stereo (ke kūlana maʻamau a maʻamau loa), a me aptX/aptX HD.

Hiki iaʻu ke lohe i ka ʻokoʻa ma waena o nā codec i nā headphone!

ʻO ka poʻe i lohe ʻole i ka ʻokoʻa ma waena o nā codecs i ka wā o ka hoʻāʻo ʻana ma o ka lawelawe pūnaewele, ʻōlelo lākou lohe lākou i ka wā e hoʻolohe ai i nā mele ma nā headphone uea. Auwe, ʻaʻole kēia he hoʻohenehene a i ʻole kahi hopena placebo: lohe maoli ʻia ka ʻokoʻa, akā ʻaʻole ma muli o nā ʻokoʻa. codecs.

ʻO ka hapa nui o nā chipsets leo Bluetooth i hoʻohana ʻia i nā hāmeʻa hoʻokipa kelepona ua lako me kahi Digital Signal Processor (DSP), kahi e hoʻokō ai i kahi equalizer, compander, stereo expander, a me nā mea ʻē aʻe i hoʻolālā ʻia e hoʻomaikaʻi (a hoʻololi paha) i ke kani. Hiki i nā mea hana o nā lako Bluetooth ke hoʻonohonoho i ka DSP no kēlā me kēia codec kaʻawale, a i ka wā e hoʻololi ai i waena o nā codecs, e noʻonoʻo ka mea hoʻolohe ke lohe nei lākou i kahi ʻokoʻa o ka hana o nā codecs, ʻoiai ke hoʻolohe nei lākou i nā hoʻonohonoho DSP like ʻole.

ʻO DSP Kalimba ka paipu hoʻoheheʻe leo i nā pahu i hana ʻia e CSR/Qualcomm

E ho'ā i nā hana DSP like ʻole no kēlā me kēia codec a me nā mea hoʻopuka

Hele mai kekahi mau mea waiwai me ka lako polokalamu e hiki ai iā ʻoe ke hoʻonohonoho i nā hoʻonohonoho DSP, akā ʻaʻole hiki i nā headphone haʻahaʻa haʻahaʻa loa, a ʻaʻole hiki i nā mea hoʻohana ke hoʻopau me ka lima.

Nā hiʻohiʻona hana o nā mea hana

Loaʻa ka mana hou o ka maʻamau A2DP "ka hoʻomalu leo ​​piha" hana - ka mana o ka leo o ka mīkini me ka hoʻohana ʻana i nā kauoha kūikawā o ka protocol AVRCP, ka mea e hoʻoponopono ai i ka loaʻa ʻana o ka pae puka, ma kahi o ka hoʻemi ʻana i ka leo o ke kahawai leo. Inā hoʻololi ʻoe i ka leo ma kāu mau poʻo, ʻaʻole like ka hoʻololi ʻana me ka leo ma kāu kelepona, a laila ʻaʻole kākoʻo kāu headphone a kelepona paha i kēia hiʻohiʻona. I kēia hihia, kūpono ke hoʻolohe mau i ke mele me ka nui o ka leo ma ke kelepona, hoʻoponopono i ka leo maoli me nā pihi headphone - i kēia hihia, ʻoi aku ka maikaʻi o ka hōʻailona hōʻailona a me ka maikaʻi o ka leo. inā paha ʻoi aku ka kiʻekiʻe.
I ka ʻoiaʻiʻo, aia nā kūlana kaumaha. Ma kaʻu mau headphone RealForce OverDrive D1 no SBC, ua hoʻohuli ʻia kahi compander ikaika, a me ka hoʻonui ʻana i ka leo e alakaʻi i ka piʻi ʻana o ke kiʻekiʻe o nā leo mālie, ʻoiai ʻaʻole loli ka leo o nā leo nui (ua hoʻopaʻa ʻia ka hōʻailona). Ma muli o kēia, pono ʻoe e hoʻonohonoho i ka leo ma ka kamepiula ma kahi o ka hapalua, ma ia hihia ʻaʻohe hopena hoʻoemi.
Wahi a kaʻu mau ʻike, kākoʻo nā headphone āpau me nā codec hou i ka hana hoʻokele leo piha, ʻike ʻia ʻo ia kekahi o nā koi no ka hōʻoia codec.

Kākoʻo kekahi mau headphone ka hoʻohui ʻana i ʻelua mau mea hana i ka manawa like. ʻAe kēia iā ʻoe, no ka laʻana, e hoʻolohe i nā mele mai kāu kamepiula a loaʻa nā kelepona mai kāu kelepona. Eia naʻe, pono ʻoe e ʻike ma kēia ʻano, ua pio nā codec ʻē aʻe a hoʻohana wale ʻia ʻo SBC.

AVDTP 1.3 Hoʻopaneʻe ka hana hōʻike hiki i nā headphone ke kamaʻilio i ka lohi i ka mea hoʻouna i hoʻokani maoli ʻia ke kani. ʻAe kēia iā ʻoe e hoʻoponopono i ka hoʻonohonoho ʻana o ka leo me ka wikiō i ka nānā ʻana i nā faila wikiō: inā he pilikia me ka hoʻouna ʻana i ka lekiō, ʻaʻole e lohi ka leo ma hope o ka wikiō, akā ma ke ʻano ʻē, e hoʻolōʻihi ʻia ke wikiō e ka mea pāʻani wikiō a hiki i ka hoʻonohonoho hou ʻia ka leo a me ka wikiō.
Kākoʻo ʻia ka hana e nā headphone he nui, Android 9+ a me Linux me PulseAudio 12.0+. ʻAʻole au i ʻike i ke kākoʻo no kēia hiʻohiʻona ma nā kahua ʻē aʻe.

Kūkākūkā ʻelua ʻaoʻao ma o Bluetooth. Hoʻouna leo.

No ka hoʻouna ʻana i ka leo ma Bluetooth, hoʻohana ʻia ʻo Synchronous Connection Oriented (SCO) - hoʻouna ʻia me ka kūkākūkā mua o ka pilina. Hāʻawi ke ʻano iā ʻoe e hoʻouna i ke kani a me ka leo ma ke ʻano, me ka hoʻouna ʻana a me ka loaʻa ʻana o nā wikiwiki, me ke kali ʻole no ka hōʻoia ʻana o ka hoʻouna ʻana a me ka hoʻouna hou ʻana i nā ʻeke. Hoʻemi kēia i ka lohi holoʻokoʻa o ka hoʻouna ʻana i ka leo ma luna o ka lekiō, akā ke kau nei i nā palena koʻikoʻi i ka nui o ka ʻikepili i hoʻouna ʻia i kēlā me kēia manawa, a hoʻopilikia i ka maikaʻi.
Ke hoʻohana ʻia kēia ʻano, hoʻouna ʻia nā leo a me nā leo me ka maikaʻi like.
ʻO ka mea pōʻino, e like me 2019, maikaʻi ʻole ka maikaʻi o ka leo ma luna o Bluetooth, a ʻaʻole maopopo i ke kumu o ka hana ʻole ʻana o ka Bluetooth SIG.

CVSD

Ua hoʻohālikelike ʻia ka codec haʻiʻōlelo CVSD maʻamau i ka makahiki 2002, a ua kākoʻo ʻia e nā mea kelepona Bluetooth bidirectional āpau. Hāʻawi ia i ka hoʻouna leo leo me ke alapine sampling o 8 kHz, e pili ana i ka maikaʻi o ke kelepona uea maʻamau.

He laʻana o ka hoʻopaʻa ʻana i kēia codec.

mSBC

Ua hoʻohālikelike ʻia ka codec mSBC hou aʻe i ka makahiki 2009, a i ka makahiki 2010 ua ʻike mua ʻia nā chips e hoʻohana ana iā ia no ka hoʻouna leo. Kākoʻo nui ʻia ka mSBC e nā mea like ʻole.
ʻAʻole kēia he codec kūʻokoʻa, akā he SBC maʻamau mai ka maʻamau A2DP, me kahi ʻaoʻao hoʻopili paʻa: 16 kHz, mono, bitpool 26.

He laʻana o ka hoʻopaʻa ʻana i kēia codec.

ʻAʻole maikaʻi, akā ʻoi aku ka maikaʻi ma mua o CVSD, akā he mea hoʻonāukiuki ke hoʻohana no ka kamaʻilio pūnaewele, ʻoiai ke hoʻohana nei ʻoe i nā headphone e kamaʻilio i loko o ka pāʻani - e hoʻouna ʻia ka leo o ka pāʻani ma kahi helu sampling o 16 kHz.

Ua hoʻoholo ka hui FastStreamCSR e hoʻomohala i ka manaʻo o ka hoʻohana ʻana iā SBC. No ka hoʻopau ʻana i nā palena o ka protocol SCO a hoʻohana i nā bitrates kiʻekiʻe, ua hele ʻo CSR i kahi ala ʻē aʻe - ua hoʻolauna lākou i ke kākoʻo no nā leo SBC ʻelua ala i ka A2DP one-way transmission standard, standardized encoding profiles, a kapa ʻia ʻo "FastStream".

Hoʻouna ʻo FastStream i ka leo stereo ma 44.1 a i ʻole 48 kHz me ka bitrate o 212 kbps i nā mea haʻiʻōlelo, a me ka mono, 16 kHz, me ka bitrate o 72 kbps i hoʻohana ʻia e hoʻouna i nā leo mai ka microphone (ʻoi aku ka maikaʻi ma mua o mSBC). ʻOi aku ka maikaʻi o ia mau ʻāpana no ka kamaʻilio ʻana i nā pāʻani pūnaewele - ʻoi aku ka maikaʻi o ke kani o ka pāʻani a me nā interlocutors.

He laʻana o ka hoʻopaʻa ʻana i kēia codec (+ kani mai ka microphone, e like me mSBC).

Ua hele mai ka hui me kahi koʻokoʻo hoihoi, akā ma muli o ke kūʻē ʻana i ka maʻamau A2DP, kākoʻo wale ʻia ia i kekahi o nā transmitters o ka ʻoihana (e hana ana ma ke kāleka leo USB, ʻaʻole he mea Bluetooth), akā ʻaʻole ia. loaʻa ke kākoʻo ma nā pūʻulu Bluetooth, ʻoiai ʻaʻole liʻiliʻi ka helu o nā headphone me ke kākoʻo FastStream.

I kēia manawa, kākoʻo ʻo FastStream i ka OS wale nō ma ke ʻano he papa no Linux PulseAudio mai ka mea hoʻomohala ʻo Pali Rohár, ʻaʻole i komo i ka lālā nui o ka papahana.

aptX Latency Haahaa

Mahalo nui iā ʻoe, kākoʻo pū ʻo aptX Low Latency i ka leo bidirectional, e hoʻokō ana i ke kumu like me FastStream.
ʻAʻole hiki ke hoʻohana i kēia hiʻohiʻona o ka codec ma nā wahi a pau - ʻaʻohe kākoʻo no ka hoʻololi ʻana i ka Latency haʻahaʻa ma kekahi OS a i ʻole ma kekahi pūʻulu Bluetooth i ʻike iaʻu.

Bluetooth 5, Kahiko a me ka ikehu haahaa

Ua nui ka huikau e pili ana i nā kikoʻī Bluetooth a me nā mana ma muli o ka loaʻa ʻana o ʻelua mau kūlana kūpono ʻole ma lalo o ka hōʻailona like, ua hoʻohana nui ʻia ia mau mea ʻelua no nā kumu like ʻole.

ʻElua mau ʻokoʻa Bluetooth like ʻole: Bluetooth Classic a me Bluetooth Low Energy (LE, ʻike ʻia ʻo Bluetooth Smart). Aia kekahi protocol ʻekolu, ʻo Bluetooth High Speed, akā ʻaʻole ia i laha ʻia a ʻaʻole hoʻohana ʻia i nā polokalamu ʻohana.

Hoʻomaka me Bluetooth 4.0, hoʻololi i ka kikoʻī e pili ana i ka Bluetooth Low Energy, a ua loaʻa i ka mana Classic nā hoʻomaikaʻi liʻiliʻi wale nō.

Ka papa inoa o nā hoʻololi ma waena o Bluetooth 4.2 a me Bluetooth 5:

9 HOOLOLI MAI v4.2 a i 5.0

9.1 ANO HOU

Hoʻokomo ʻia kekahi mau hiʻohiʻona hou i ka Bluetooth Core Specification 5.0 Release. ʻO nā wahi nui o ka hoʻomaikaʻi ʻana:
• Māka Loa Loaʻa ʻia (SAM)
• 2 Msym/s PHY no LE
•LE Kaulana
• Kiekie Duty Cycle Non-Connectable Advertising
• Nā hoʻolaha hoʻolaha LE
• Ka Algorithm Koho Ike Kanal LE #2
9.1.1 Hoʻohui ʻia nā hiʻohiʻona ma CSA5 - Hoʻohui ʻia i v5.0
•Ka Mana Puke Kiekie

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

Hoʻokahi wale nō hoʻololi i hoʻopili i ka mana Classic i loko o ke kāʻei o ka kikoʻī Bluetooth 5: ua hoʻohui lākou i ke kākoʻo no ka ʻenehana Slot Availability Mask (SAM), i hoʻolālā ʻia e hoʻomaikaʻi i ka hoʻokaʻawale ʻana i ka lekiō. ʻO nā hoʻololi ʻē aʻe a pau e pili ana i ka Bluetooth LE wale nō (a me ka Higher Output Power pū kekahi).

a pau Hoʻohana wale nā ​​mea leo leo Bluetooth Classic wale nō. ʻAʻole hiki ke hoʻopili i nā headphone a me nā mea ʻōlelo ma o Bluetooth Low Energy: ʻaʻohe maʻamau no ka hoʻouna ʻana i ka leo me ka hoʻohana ʻana i ka LE. ʻO ka maʻamau A2DP, hoʻohana ʻia no ka hoʻouna ʻana i nā leo kiʻekiʻe, hana wale ma o Bluetooth Classic, a ʻaʻohe analogue ma LE.

Ka hopena - ke kūʻai ʻana i nā leo leo me Bluetooth 5 wale nō ma muli o ka mana hou o ka protocol he mea ʻole. ʻO Bluetooth 4.0/4.1/4.2 i ka pōʻaiapili o ka hoʻouna leo e hana like.
Inā ʻōlelo ka hoʻolaha ʻana o nā headphone hou i ka pālua o ka hana a me ka hoʻemi ʻana i ka hoʻohana ʻana i ka mana e hoʻomaikaʻi iā Bluetooth 5, a laila pono ʻoe e ʻike ʻaʻole maopopo lākou iā lākou iho a ke alakaʻi hewa nei paha iā ʻoe. ʻAʻohe mea kupanaha, no ka mea, huikau nā mea hana o Bluetooth chips i kā lākou mau hoʻolaha e pili ana i nā ʻokoʻa ma waena o ka mana hou o ka maʻamau, a kākoʻo kekahi mau ʻāpana Bluetooth 5 i ka mana ʻelima wale nō no LE, a hoʻohana i ka 4.2 no Classic.

Hoʻopaneʻe ka hoʻouna leo

ʻO ka nui o ka lohi (lag) i ka leo e pili ana i nā kumu he nui: ʻo ka nui o ka buffer i loko o ka waihona leo, i ka pūʻulu Bluetooth a me ka hāmeʻa pāʻani kelepona ponoʻī, a me ka lohi algorithmic o ke codec.

ʻO ka latency o nā codec maʻalahi e like me SBC, aptX a me aptX HD liʻiliʻi loa, 3-6 ms, hiki ke mālama ʻole ʻia, akā hiki i nā codec paʻakikī e like me AAC a me LDAC ke kumu i ka lag ʻike. ʻO ka latency algorithmic AAC no 44.1 kHz he 60 ms. LDAC - ma kahi o 30 ms (e pili ana i kahi loiloi koʻikoʻi o ke kumu kumu. Ua hewa paha wau, akā ʻaʻole nui.)

ʻO ka hopena o ka latency e hilinaʻi nui ʻia i ka hāmeʻa pāʻani, kāna chipset a me ka buffer. I ka wā o nā hoʻokolohua, loaʻa iaʻu kahi pālahalaha o 150 a 250 ms ma nā mea like ʻole (me ka codec SBC). Inā manaʻo mākou e hoʻohana ana nā hāmeʻa e kākoʻo ana i nā codec hou aptX, AAC a me LDAC i nā ʻāpana kiʻekiʻe a me ka nui buffer liʻiliʻi, loaʻa iā mākou nā latencies maʻamau:

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

E hoʻomanaʻo wau iā ʻoe: ʻaʻole kākoʻo ʻia ka aptX Low Latency i nā ʻōnaehana hana, ʻo ia ke kumu e hiki ai ke loaʻa i ka latency haʻahaʻa me kahi transmitter+receiver a i ʻole transmitter+headphones/speaker hui, a pono nā mea hana āpau e kākoʻo i kēia codec.

ʻO ka hāmeʻa Bluetooth, ka palapala hōʻoia, a me nā pilikia logo

Pehea e hoʻokaʻawale ai i kahi leo leo kiʻekiʻe mai kahi mea hana liʻiliʻi? I ka helehelena, mua loa!

No nā poʻo poʻo poʻo Pākē haʻahaʻa, nā mea ʻōlelo a me nā mea hoʻokipa:

1. Nalo ka huaʻōlelo "Bluetooth" ma ka pahu a me ka hāmeʻa, "Wireless" a me "BT" i hoʻohana pinepine ʻia.
2. Nalo ka logo Bluetooth ma ka pahu a mea paha
3. ʻAʻohe LED uila uila

ʻO ka nele o kēia mau mea e hōʻike ana ʻaʻole i hōʻoia ʻia ka hāmeʻa, ʻo ia hoʻi he haʻahaʻa haʻahaʻa a pilikia. No ka laʻana, ʻaʻole i hōʻoia ʻia nā headphone Bluedio a ʻaʻole i hoʻokō piha i ka kikoʻī A2DP. ʻAʻole lākou i hala i ka palapala hōʻoia.

E noʻonoʻo kākou i kekahi mau mea hana a me nā pahu mai iā lākou:

ʻO kēia nā mea i hōʻoia ʻole ʻia. Loaʻa paha i nā ʻōlelo aʻoaʻo kahi hōʻailona a me ka inoa o ka ʻenehana Bluetooth, akā ʻo ka mea nui loa aia lākou ma ka pahu a / a i ʻole ka hāmeʻa ponoʻī.

Inā ʻōlelo kāu poʻo poʻo a ʻōlelo paha "Hoʻohui maikaʻi ʻia ʻo Ze bluetooth dewise", ʻaʻole ia e hōʻike i ko lākou ʻano maikaʻi:

hopena

Hiki iā Bluetooth ke hoʻololi piha i nā headphone uea a me nā headset? Hiki iā ia, akā ma ke kumu kūʻai o ka maikaʻi kelepona maikaʻi ʻole, hoʻonui ʻia ka latency leo i hiki ke hoʻonāukiuki i nā pāʻani, a me ka lehulehu o nā codecs proprietary e koi ana i nā uku laikini a hoʻonui i ke kumukūʻai hope o nā smartphones a me nā headphone.

He ikaika loa ke kūʻai aku ʻana i nā codecs ʻē aʻe: ua hōʻike ʻia ʻo aptX a me LDAC ma ke ʻano he pani lōʻihi i kali ʻia no ka SBC "kahiko a maikaʻi ʻole", ʻaʻole i like ka hewa e like me ka manaʻo o ka poʻe.

E like me ka mea i ʻike ʻia, hiki ke kāpae ʻia nā palena hana o Bluetooth ma ka bitrate SBC, i ʻole e emi ka SBC i ka aptX HD. Ua lawe au i ka hana i loko o koʻu mau lima ponoʻī a ua hana i kahi papa no ka firmware LineageOS: Hoʻololi mākou i ka pūʻulu Bluetooth e hoʻomaikaʻi i ke kani ma nā headphone me ka ʻole o nā codec AAC, aptX a me LDAC

Hiki ke loaʻa nā ʻike hou aku ma nā pūnaewele Hoohui и Kaʻike leo.

Bonus: SBC reference encoder, A2DP bitstream ʻike a me nā faila hoʻāʻo. Ua hoʻolaha mua ʻia kēia faila ma ka pūnaewele Bluetooth, akā i kēia manawa aia wale nō i nā lālā o ka Bluetooth SIG.

Source: www.habr.com