无法通过蓝牙将音频发送到 Amazon Echo

Question

我有一台 Amazon Echo 和一台运行 Ubuntu 16.04.1 的笔记本电脑。我可以通过蓝牙成功配对设备（Echo 说Now connected to <my machine's name>），但是当我测试声音时，什么也听不到。音量足够高，其他设备可以很好地连接到 Echo。

这是dmesg输出：

$ dmesg | grep -i blue
[   12.419477] Bluetooth: Core ver 2.21
[   12.419491] Bluetooth: HCI device and connection manager initialized
[   12.419494] Bluetooth: HCI socket layer initialized
[   12.419497] Bluetooth: L2CAP socket layer initialized
[   12.419502] Bluetooth: SCO socket layer initialized
[   12.473236] Bluetooth: hci0: read Intel version: 370810011003110e00
[   12.480889] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[   12.839251] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[   13.386452] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[   13.386456] Bluetooth: BNEP filters: protocol multicast
[   13.386460] Bluetooth: BNEP socket layer initialized
[   16.473284] Bluetooth: RFCOMM TTY layer initialized
[   16.473292] Bluetooth: RFCOMM socket layer initialized
[   16.473297] Bluetooth: RFCOMM ver 1.11
[10944.651128] Bluetooth: hci0: read Intel version: 370810011003110e00
[10944.651133] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[10944.977821] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[24061.878085] Bluetooth: hci0: read Intel version: 370810011003110e00
[24061.887184] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[24062.211121] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[24072.874829] Bluetooth: hci0: read Intel version: 370810011003110e00
[24072.874835] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[24073.196858] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[45209.076985]  iwlwifi videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 serio_raw videobuf2_core btrtl btbcm btintel input_leds bluetooth snd_hda_codec_realtek(OE) snd_hda_codec_generic(OE) snd_hda_codec_hdmi(OE) v4l2_common snd_seq_midi joydev cfg80211 snd_seq_midi_event videodev media snd_hda_intel(OE) snd_hda_codec(OE) snd_hda_core(OE) snd_hwdep lpc_ich snd_pcm snd_rawmidi shpchp snd_seq mei_me mei snd_seq_device snd_timer snd elan_i2c int3403_thermal 8250_fintek soundcore 8250_dw i2c_designware_platform dw_dmac snd_soc_sst_acpi i2c_designware_core dell_smo8800 dw_dmac_core processor_thermal_device spi_pxa2xx_platform int3402_thermal int3400_thermal int340x_thermal_zone acpi_thermal_rel intel_soc_dts_iosf dell_rbtn acpi_als mac_hid acpi_pad kfifo_buf industrialio parport_pc ppdev lp parport autofs4
[55174.636122] Bluetooth: hci0: read Intel version: 370810011003110e00
[55174.646073] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[55174.970198] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[55181.295879] Bluetooth: hci0: read Intel version: 370810011003110e00
[55181.295922] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[55181.670006] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[56551.946597] Bluetooth: hci0: read Intel version: 370810011003110e00
[56551.955475] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[56552.282610] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[98502.038807] Bluetooth: hci0: read Intel version: 370810011003110e00
[98502.038816] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[98502.356833] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[107908.657215] Bluetooth: hci0: read Intel version: 370810011003110e00
[107908.657298] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[107908.985251] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[109042.464364] Bluetooth: hci0: read Intel version: 370810011003110e00
[109042.464372] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[109042.782838] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[109052.807963] Bluetooth: hci0: read Intel version: 370810011003110e00
[109052.807968] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[109053.127969] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated
[127570.876446] Bluetooth: hci0: read Intel version: 370810011003110e00
[127570.953632] Bluetooth: hci0: Intel Bluetooth firmware file: intel/ibt-hw-37.8.10-fw-1.10.3.11.e.bseq
[127571.270715] Bluetooth: hci0: Intel Bluetooth firmware patch completed and activated

Answer 1

我也有这个问题。配对并将音频发送到其他蓝牙扬声器有效。与 Amazon Echo 配对有效，但听不到任何声音。我正在使用 Ubuntu 16.04 LTS (Xenial)，它是从今天的 15.10 (Wily) 升级而来的，而后者又是从 14.04 LTS (Trusty) 升级的。（我提到这一点是因为我想知道问题是否可能特定于升级路径与全新安装。）

我认为问题与pulseaudio将设备配对为耳机而不仅仅是扬声器的事实有关。这需要a2dp，对我来说，这似乎是发生故障的地方。

例如，当我与我的 Bose SoundLink II（从 14.04 开始工作并且一直有效）配对时，dmesg显示：

Feb 28 10:57:04 n1 bluetoothd[1025]: /org/bluez/hci0/dev_00_0C_8A_58_F6_CA/fd2: fd(22) ready
Feb 28 10:57:04 n1 bluetoothd[1025]: No pending request, ignoring message
Feb 28 10:57:04 n1 kernel: [ 1053.711796] input: 00:0C:8A:58:F6:CA as /devices/virtual/input/input20

但是，当我与 Amazon Echo 配对时，dmesg报告：

Feb 28 10:59:05 n1 bluetoothd[1025]: a2dp-source profile connect failed for 50:F5:DA:A6:3F:EA: Device or resource busy
Feb 28 10:59:05 n1 bluetoothd[1025]: /org/bluez/hci0/dev_50_F5_DA_A6_3F_EA/fd3: fd(22) ready
Feb 28 10:59:05 n1 kernel: [ 1174.849178] input: 50:F5:DA:A6:3F:EA as /devices/virtual/input/input21

上面输出中的关键行是第一行，其中 a2dp 报告设备或资源繁忙。

我四处寻找解决方案，但到目前为止还没有运气。MrUser 在问题 #440386 的讨论中提出的答案表明该问题可能与“... a2dp 已移出 BlueZ 堆栈并移入 GStreamer ”有关，并且他通过自己编译pulseaudio 5.x 取得了一些成功。但是，Ubuntu 16.04.2 LTS 使用pulseaudio 8.0，而不是5.x，此外，上面的错误消息表明我的系统上的pulseaudio确实支持a2dp，但是在bluetoothd 连接设备后a2dp 由于某种原因无法访问该设备。

这让我相信问题可能是由于权限或访问权限的问题，但我不能确定。

问题 #763539和其他地方的讨论表明，切换到 HSP/HFP 模式，然后再回到 A2DP 模式可以解决问题，但这适用于 KDE（即 Kubuntu）。我曾尝试使用@pylover 提供的 a2dp.py 脚本。它运行良好，但仍然出现a2dp“设备或资源繁忙”错误并且问题没有解决。

如果可以找到时间，我将打开蓝牙调试（如Ubuntu 的 Wiki 所述）并报告我的发现。我的感觉是，这个问题是可以修复的，而且问题很简单，但准确地追踪故障点并进行更正并非易事。

如果其他人对这个问题和可能的解决方案有见解，我将不胜感激。