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企业邮箱邮箱_白嫖云服务器_百度视频推广_做网页设计的软件

时间:2025/7/10 18:05:26来源:https://blog.csdn.net/Jzj1234555/article/details/145593501 浏览次数:0次
企业邮箱邮箱_白嫖云服务器_百度视频推广_做网页设计的软件

LE AUDIO录音的优势

经典蓝牙TWS耳机录音一般采用的方案都是利用耳机麦克风拾音,然后通过ADC模数转换成数字信号PCM,DSP会将PCM数据经过音频编码(如SBC,LC3等)保存在本地,或者可以启用SPP协议实时传输至手机端。然后经典蓝牙TWS耳机实际上只有主耳与手机端建立ACL连接,副耳是采用监听方式,如果需要实时录音势必只有主耳能录音,副耳无法录音(无法传输数据至手机),这样就成了单声道录音。
而如果采用LE AUDIO方式的话,因为主副耳都与手机有ACL链路连接,各自录音也可以通过各自的CIS通道传输至手机,这样就可以进行双耳立体声录音了。

下面我们结合一个实例从HCI层来分析完整的LE AUDIO双耳立体声录音的协议流程:

LE AUDIO录音协议流程

LE连接建立

手机先与主耳建立BR连接,然后CTKD获得LTK后直接进行SMP Key Distribution,接着双方建立LE连接:在这里插入图片描述在这里插入图片描述

开启LE AUDIO相关ATT Primary Service查询

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  1. ATT Read By Group Type Transaction (3’846 - Max Handle, Primary Service: Battery, Volume Control, Coordinated Set Identification)
  2. ATT Read By Group Type Transaction (18’176 - Max Handle, Primary Service: Microphone Control, Audio Stream Control, Broadcast Audio Scan)
  3. ATT Read By Group Type Transaction (20’480 - Max Handle, Primary Service: Published Audio Capability, Common Audio, Telephony and Media Audio)

开启Primary service下特征值的查询

  1. ATT Read By Type Transaction (17’408 - 17’663, Characteristic Declaration: [17’410=Volume State, Read, Notify], [17’413=Volume Control Point, Write], [17’415=Volume Flags, Read, Notify])
  2. ATT Read By Type Transaction (17’920 - 18’175, Characteristic Declaration: [17’922=Set Identity Resolving Key, Read, Notify], [17’925=Size, Read, Notify], [17’928=Lock, Read, Write, Notify])
  3. ATT Read By Type Transaction (17’928 - 18’175, Characteristic Declaration: 17’931=Rank, Read)
  4. ATT Read By Type Transaction (19’712 - 19’967, Characteristic Declaration: 19’714=Mute, Read, Write, Notify)
  5. ATT Read By Type Transaction (19’968 - 20’223, Characteristic Declaration: [19’970=ASE Control Point, Write w/o Resp, Write, Notify], [19’973=Sink ASE, Read, Notify], [19’976=Sink ASE, Read, Notify])
  6. ATT Read By Type Transaction (19’976 - 20’223, Characteristic Declaration: [19’979=Source ASE, Read, Notify], [19’982=Source ASE, Read, Notify])
  7. ATT Read By Type Transaction (20’224 - 20’479, Characteristic Declaration: [20’226=Broadcast Audio Scan Control Point, Write w/o Resp, Write], [20’228=Broadcast Receive State, Read, Notify])
  8. ATT Read By Type Transaction (20’480 - 20’735, Characteristic Declaration: [20’482=Available Audio Contexts, Read, Notify], [20’485=Supported Audio Contexts, Read, Notify], [20’488=Sink Audio Locations, Read, Write, Notify])
  9. ATT Read By Type Transaction (20’488 - 20’735, Characteristic Declaration: [20’491=Source Audio Locations, Read, Write, Notify], [20’494=Sink PAC, Read, Notify], [20’497=Source PAC, Read, Notify])
    10.ATT Read By Type Transaction (21’248 - 21’503, Include: Included=17’920, End=18’175, Service=Coordinated Set Identification)

读取Identity resolving key

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耳机进行TBS和GMCS服务查询

这里的0x1849 UUID是 Generic Media Control Service。
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  1. ATT Read By Type Transaction (110 - 146, Characteristic Declaration: [112=Bearer Provider Name, Read, Notify], [115=Bearer UCI, Read], [117=Bearer Technology, Read, Notify], [120=Bearer URI Schemes, Read, Notify], [123=Bearer List Current Calls, Read, Notify], [126=Content Control ID, Read], [128=Status Flags, Read, Notify], [131=Call State, Read, Notify], [134=Call Control Point, Write w/o Resp, Write, Notify], [137=Call Control Point Optional Opcodes, Read], [139=Termination Reason, Notify], [142=Incoming Call, Read, Notify], [145=Call Friendly Name, Read, Notify])
  2. ATT Read By Type Transaction (60 - 97, Characteristic Declaration: [62=Media Player Name, Read, Notify], [65=Track Changed, Notify], [68=Track Title, Read, Notify], [71=Track Duration, Read, Notify], [74=Track Position, Read, Write w/o Resp, Write, Notify], [77=Playback Speed, Read, Write w/o Resp, Write, Notify], [80=Seeking Speed, Read, Notify], [83=Playing Order, Read, Write w/o Resp, Write, Notify], [86=Playing Orders Supported, Read], [88=Media State, Read, Notify], [91=Media Control Point, Write w/o Resp, Write, Notify], [94=Media Control Point Supported, Read, Notify], [97=Content Control ID, Read])

手机和副耳进行LE连接配对

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副耳会和主耳共用相同的service和特征值,所以后面副耳无需再做查询。

读取主副耳的PAC

  1. ATT Read (Available Audio Contexts: Unspecified, Conversational, Media, Game, Instructional, Voice assistants, Live, Sound effects, Notifications, Ringtone, Alerts, Emergency alarm, Unspecified, Conversational, Media, Game, Instructional, Voice assistants, Live, Sound effects, Notifications, Ringtone, Alerts, Emergency alarm)
  2. ATT Read (Supported Audio Contexts: Unspecified, Conversational, Media, Game, Instructional, Voice assistants, Live, Sound effects, Notifications, Ringtone, Alerts, Emergency alarm, Unspecified, Conversational, Media, Game, Instructional, Voice assistants, Live, Sound effects, Notifications, Ringtone, Alerts, Emergency alarm)
  3. ATT Read (Sink PAC: N=1, Coding Format=LC3, Company ID=0, Vendor Specific Codec ID=0, Type=Supported Sampling Frequencies, 16000 Hz, 24000 Hz, 32000 Hz, 48000 Hz, Type=Supported Frame Durations, 7.5 ms, 10 ms, Type=Supported Octets Per Codec Frame, Min=26, Max=155, Type=Preferred Audio Contexts, Conversational, Media)
  4. ATT Read (Source PAC: N=1, Coding Format=LC3, Company ID=0, Vendor Specific Codec ID=0, Type=Supported Sampling Frequencies, 16000 Hz, 32000 Hz, 48000 Hz, Type=Supported Frame Durations, 7.5 ms, 10 ms, Type=Supported Octets Per Codec Frame, Min=26, Max=155, Type=Preferred Audio Contexts, Conversational, Media)

对主副耳进行ASCS code & qos config

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创建主副耳的CIS

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  1. 在ASCS code config之后,手机会发起HCI LE Set CIG Parameters和HCI Configure Data Path。
  2. 在ASCS Enable Type=Stream audio context ,Live 之后创建2路CIS。
  3. 手机发起设置HCI LE Setup ISO Data Path

手机发起主副耳录音

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