我使用的是Baytrail intel z3735平板电脑。我正在尝试使用Linux内核版本3.16 / 4.2.0运行ubuntu 14.04 / 15.04。当我播放音频文件时，音频数据会转储到音频接收器，但扬声器没有音频。我能够检测到声卡如下...
sanj@sanj:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: bytrt5640 [byt-rt5640], device 0: Audio rt5640-aif1-0 []
Subdevices: 1/1
Subdevice #0: subdevice #0
sanj@sanj:~$
音频接收节点：
sanj@sanj:~$ pactl list sinks
Sink #0
State: SUSPENDED
Name: alsa_output.platform-byt-rt5640.analog-stereo
Description: byt-rt5640 Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 48000Hz
Channel Map: front-left,front-right
Owner Module: 6
Mute: no
Volume: front-left: 99957 / 153% / 11.00 dB, front-right: 99957 / 153% / 11.00 dB
balance 0.00
Base Volume: 41350 / 63% / -12.00 dB
Monitor Source: alsa_output.platform-byt-rt5640.analog-stereo.monitor
Latency: 0 usec, configured 0 usec
Flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY
Properties:
alsa.resolution_bits = "16"
device.api = "alsa"
device.class = "sound"
alsa.class = "generic"
alsa.subclass = "generic-mix"
alsa.name = ""
alsa.id = "Audio rt5640-aif1-0"
alsa.subdevice = "0"
alsa.subdevice_name = "subdevice #0"
alsa.device = "0"
alsa.card = "0"
alsa.card_name = "byt-rt5640"
alsa.long_card_name = "byt-rt5640"
alsa.driver_name = "snd_soc_sst_byt_rt5640_mach"
device.bus_path = "platform-byt-rt5640"
sysfs.path = "/devices/platform/80860F28:00/byt-rt5640/sound/card0"
device.string = "hw:0"
device.buffering.buffer_size = "96000"
device.buffering.fragment_size = "48000"
device.access_mode = "mmap+timer"
device.profile.name = "analog-stereo"
device.profile.description = "Analog Stereo"
device.description = "byt-rt5640 Analog Stereo"
module-udev-detect.discovered = "1"
device.icon_name = "audio-card"
Ports:
analog-output-speaker: Speakers (priority: 10000)
analog-output-headphones: Headphones (priority: 9000)
Active Port: analog-output-speaker
Formats:
pcm
音频源节点：
sanj@sanj:~$ pactl list sources
Source #0
State: SUSPENDED
Name: alsa_output.platform-byt-rt5640.analog-stereo.monitor
Description: Monitor of byt-rt5640 Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 48000Hz
Channel Map: front-left,front-right
Owner Module: 6
Mute: no
Volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
Base Volume: 65536 / 100% / 0.00 dB
Monitor of Sink: alsa_output.platform-byt-rt5640.analog-stereo
Latency: 0 usec, configured 0 usec
Flags: DECIBEL_VOLUME LATENCY
Properties:
device.description = "Monitor of byt-rt5640 Analog Stereo"
device.class = "monitor"
alsa.card = "0"
alsa.card_name = "byt-rt5640"
alsa.long_card_name = "byt-rt5640"
alsa.driver_name = "snd_soc_sst_byt_rt5640_mach"
device.bus_path = "platform-byt-rt5640"
sysfs.path = "/devices/platform/80860F28:00/byt-rt5640/sound/card0"
device.string = "0"
module-udev-detect.discovered = "1"
device.icon_name = "audio-card"
Formats:
pcm
Source #1
State: SUSPENDED
Name: alsa_input.platform-byt-rt5640.analog-stereo
Description: byt-rt5640 Analog Stereo
Driver: module-alsa-card.c
Sample Specification: s16le 2ch 48000Hz
Channel Map: front-left,front-right
Owner Module: 6
Mute: no
Volume: front-left: 93554 / 143% / 9.27 dB, front-right: 93554 / 143% / 9.27 dB
balance 0.00
Base Volume: 65536 / 100% / 0.00 dB
Monitor of Sink: n/a
Latency: 0 usec, configured 0 usec
Flags: HARDWARE DECIBEL_VOLUME LATENCY
Properties:
alsa.resolution_bits = "16"
device.api = "alsa"
device.class = "sound"
alsa.class = "generic"
alsa.subclass = "generic-mix"
alsa.name = ""
alsa.id = "Audio rt5640-aif1-0"
alsa.subdevice = "0"
alsa.subdevice_name = "subdevice #0"
alsa.device = "0"
alsa.card = "0"
alsa.card_name = "byt-rt5640"
alsa.long_card_name = "byt-rt5640"
alsa.driver_name = "snd_soc_sst_byt_rt5640_mach"
device.bus_path = "platform-byt-rt5640"
sysfs.path = "/devices/platform/80860F28:00/byt-rt5640/sound/card0"
device.string = "hw:0"
device.buffering.buffer_size = "96000"
device.buffering.fragment_size = "48000"
device.access_mode = "mmap+timer"
device.profile.name = "analog-stereo"
device.profile.description = "Analog Stereo"
device.description = "byt-rt5640 Analog Stereo"
module-udev-detect.discovered = "1"
device.icon_name = "audio-card"
Ports:
analog-input: Analog Input (priority: 10000)
Active Port: analog-input
Formats:
pcm
sanj@sanj:~$
为了测试音频是否即将到来，我正在使用来自不同终端的pulseaudio命令 paplay 和 parecord 。由于源0是汇聚节点0的源监控节点，因此我从中捕获了音频。
sanj@sanj:~$ paplay Dhaakad.wav
sanj@sanj:~$ parecord -d 0 > test.wav
然后我在PC上用大胆测试了捕获的音频文件 test.wav 并且播放正常。我无法弄清楚为什么音频不是来自扬声器。我还尝试使用 alsamixer 更改音频设置，但没有任何效果。