RPI 4: Arecord the audio stream from the phone through Bluezalsa

[Arika-Lei]

Problem

My test board is Raspberry 4, l try to use Bluezalsa to arecord the audio stream from the phone, but something errors happened:

root@raspberrypi:/home/pi# arecord -D bluealsa:DEV=A4:CC:B3:7C:24:27 -f S16_le -c 2 -r 44100 test.wav [2152] D: ../../../src/asound/bluealsa-pcm.c:1473: Getting BlueALSA PCM: CAPTURE A4:CC:B3:7C:24:27 a2dp [2152] D: ../../../src/asound/bluealsa-pcm.c:1222: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Setting constraints Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo [2152] D: ../../../src/asound/bluealsa-pcm.c:561: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Initializing HW [2152] D: ../../../src/asound/bluealsa-pcm.c:581: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Couldn't open PCM: Device or resource busy arecord: set_params:1416: Unable to install hw params: ACCESS: RW_INTERLEAVED FORMAT: S16_LE SUBFORMAT: STD SAMPLE_BITS: 16 FRAME_BITS: 32 CHANNELS: 2 RATE: 44100 PERIOD_TIME: 125000 PERIOD_SIZE: (5512 5513) PERIOD_BYTES: 22050 PERIODS: 4 BUFFER_TIME: 500000 BUFFER_SIZE: 22050 BUFFER_BYTES: 88200 TICK_TIME: 0 [2152] D: ../../../src/asound/bluealsa-pcm.c:471: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Closing

Reproduction steps

l installed 'bluez-alsa-utils' from Debian. l reboot RPI 4, and then connect the bluetooth from my phone (The bluetooth audio codec l choose SBC). Then, l try 'arecord‘ command to capture the audio stream from my phone, but not success. Then l try 'bluealsa-aplay -l' to confirm the device and my phone has been recognized.

root@raspberrypi:/home/pi# bluealsa-aplay -l List of PLAYBACK Bluetooth Devices List of CAPTURE Bluetooth Devices hci0: A4:CC:B3:7C:24:27 [Redmi], trusted phone A2DP (SBC): S16_LE 2 channels 44100 Hz

Setup

• bluez-alsa-utils is already the newest version (4.0.0-2).
• the version of BlueALSA (bluealsa --version): v4.0.0
• the version of BlueZ (bluetoothd --version): 5.66
• the version of ALSA (aplay --version): version 1.2.8

Additional context

l didn't setup my local .asoundrc file and it is empty in my asound.conf, is there something wrong with that?

[Arika-Lei]

l stop the bluealsa-aplay service, capture is OK! But when l replay the recorded audio file, it sounds like...fast forward? (Music on the phone has played almost 20 seconds, recorded file is just 2 seconds)

[borine]

l didn't setup my local .asoundrc file and it is empty in my asound.conf

Those files are not necessary, and it is usually easier to debug without them, so that is OK.

But when l replay the recorded audio file, it sounds like...fast forward?

If you have the ffmpeg package installed, please post the output of

ffprobe -hide_banner test.wav

or if not, then the output of

file test.wav
ls -l test.wav

where test.wav is the file created by

arecord -D bluealsa:DEV=A4:CC:B3:7C:24:27 -f S16_le -c 2 -r 44100 test.wav

[Arika-Lei]

It's very nice of you to reply so fast.

that is the result of the command: root@raspberrypi:/home/pi# file test.wav test.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, stereo 44100 Hz

root@raspberrypi:/home/pi# ls -l test.wav -rw-r--r-- 1 root root 5644332 Jun 18 09:39 test.wav

root@raspberrypi:/home/pi# ffprobe -hide_banner test.wav [wav @ 0x55a7f5beb0] Estimating duration from bitrate, this may be inaccurate Input #0, wav, from 'test.wav': Duration: 00:00:32.00, bitrate: 1411 kb/s Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, 2 channels, s16, 1411 kb/s

and that is the process: root@raspberrypi:/home/pi# arecord -D bluealsa:DEV=A4:CC:B3:7C:24:27 -f S16_le -c 2 -r 44100 test.wav [2381] D: ../../../src/asound/bluealsa-pcm.c:1473: Getting BlueALSA PCM: CAPTURE A4:CC:B3:7C:24:27 a2dp [2381] D: ../../../src/asound/bluealsa-pcm.c:1222: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Setting constraints Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo [2381] D: ../../../src/asound/bluealsa-pcm.c:561: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Initializing HW [2381] D: ../../../src/asound/bluealsa-pcm.c:600: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: FIFO buffer size: 16384 frames [2381] D: ../../../src/asound/bluealsa-pcm.c:605: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Selected HW buffer: 4 periods x 22048 bytes <= 88200 bytes [2381] D: ../../../src/asound/bluealsa-pcm.c:636: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Initializing SW [2381] D: ../../../src/asound/bluealsa-pcm.c:636: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Initializing SW [2381] D: ../../../src/asound/bluealsa-pcm.c:677: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Prepared [2381] D: ../../../src/asound/bluealsa-pcm.c:636: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Initializing SW [2381] D: ../../../src/asound/bluealsa-pcm.c:388: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Starting [2383] D: ../../../src/asound/bluealsa-pcm.c:231: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Starting IO loop: 7 ^CAborted by signal Interrupt... arecord: pcm_read:2221: read error: Interrupted system call [2381] D: ../../../src/asound/bluealsa-pcm.c:424: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Stopping [2383] D: ../../../src/asound/bluealsa-pcm.c:167: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: IO thread cleanup [2381] D: ../../../src/asound/bluealsa-pcm.c:615: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Freeing HW [2381] D: ../../../src/asound/bluealsa-pcm.c:471: /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source: Closing

[borine]

arecord always writes a WAV file header of 44 bytes (i.e. no content metadata), followed by the PCM audio frames. So your file contains (5644332 - 44) bytes of audio frames.

The frame size for 2ch s16_le is 4 bytes, so your file contains ((5644332 - 44) / 4) PCM frames.

So, sampled at 44100 frames per second, your file contains 32 seconds of audio.

I can only assume that your playback application is playing it at the wrong speed if it is only taking 2 seconds to play it!

[Arika-Lei]

l'm sorry for that l had a new record today. The playback application also displays almost 32 seconds, but actually l have played maybe 1m10s on my phone. l have played the 32 seconds audio file, and the speed looks like fast->normal->fast... l cannot say the exact playtime now because l have broken the environment...

Today l tried to install bluez-alsa from Github, so l remove the 'bluez-alsa-utils' from Debian. After l installed FDK-AAC from Github, l tried the following steps:

download the current code git clone https://github.com/Arkq/bluez-alsa.git cd bluez-alsa

configure build environment only after all dependencies are done autoreconf --install --force mkdir build cd build

based on existing Moode build scripts with aac enabled ../configure --disable-hcitop --with-alsaplugindir=/usr/lib/arm-linux-gnueabihf/alsa-lib --enable-aac

compile and install make sudo make install

reboot and test sudo reboot

Problem root@raspberrypi:/home/pi# sudo systemctl enable bluealsa.service Failed to enable unit: Unit file bluealsa.service does not exist. root@raspberrypi:/home/pi# sudo systemctl enable bluealsa-aplay.service Failed to enable unit: Unit file bluealsa-aplay.service does not exist. root@raspberrypi:/home/pi# sudo systemctl start bluealsa.service Failed to start bluealsa.service: Unit bluealsa.service not found.

l cannot start the bluealsa.service and bluealsa-aplay.service :(

Additional context First command l tried: root@raspberrypi:/home/pi# ls /usr/lib/arm-linux-gnueabihf/alsa-lib libasound_module_ctl_bluealsa.a libasound_module_pcm_bluealsa.a libasound_module_ctl_bluealsa.la libasound_module_pcm_bluealsa.la libasound_module_ctl_bluealsa.so libasound_module_pcm_bluealsa.so

Second command l tried: root@raspberrypi:/home/pi# sudo bluealsa -i hci0 -p a2dp-source -p a2dp-sink bluealsa: W: UUID already registered in BlueZ [hci0]: 0000110A-0000-1000-8000-00805F9B34FB bluealsa: W: UUID already registered in BlueZ [hci0]: 0000110B-0000-1000-8000-00805F9B34FB

Third command l tried: root@raspberrypi:/home/pi# sudo systemctl daemon-reload

Forth command l tried: root@raspberrypi:/home/pi# ls /usr/lib/systemd/system/bluealsa.service ls: cannot access '/usr/lib/systemd/system/bluealsa.service': No such file or directory root@raspberrypi:/home/pi# ls /etc/systemd/system/bluealsa.service ls: cannot access '/etc/systemd/system/bluealsa.service': No such file or directory

Fifth command l tried: root@raspberrypi:/home/pi# service --status-all [ - ] alsa-utils [ - ] apparmor [ + ] bluetooth [ - ] console-setup.sh [ + ] cron [ + ] cups [ + ] cups-browsed [ + ] dbus [ + ] dphys-swapfile [ + ] fake-hwclock [ - ] fio [ - ] hwclock.sh [ - ] keyboard-setup.sh [ + ] kmod [ + ] lightdm [ + ] networking [ - ] nfs-common [ - ] plymouth [ + ] plymouth-log [ + ] procps [ + ] raspi-config [ - ] rpcbind [ - ] rsync [ - ] saned [ + ] ssh [ - ] sudo [ + ] triggerhappy [ + ] udev [ - ] x11-common

Setup the version of BlueALSA (bluealsa --version): v4.2.0-16-gdd85a7b the version of BlueZ (bluetoothd --version): 5.66 the version of ALSA (aplay --version): version 1.2.8

[borine]

based on existing Moode build scripts

You have not said what OS you are using, but if you are using Moode then please seek help from the Moode maintainers - from what you have said above it appears that Moode does not use the BlueALSA systemd unit files; I guess they must use their own, so you will have to make sure you have them installed.

If you are not using Moode, then its probably best not to use their build scripts because they are clearly specialized for the Moode environment. Instead, follow the guidance on the wiki - the configure options for using systemd are explained there. If you need AAC support I suggest you try

../configure --enable-systemd --enable-aac 

... and also, please make sure you do not have pulseaudio or pipewire running.

[Arika-Lei]

The OS l am using is Raspberry Pi 4 64bit under Debian. l was not aware that l had used another environment (till today l get to know what Moode is). Fortunately, l follow the right way, bluealsa starts again, and has AAC, aptX, LDAC installed! (../configure --enable-systemd --enable-aac --enable-aptx --with-libopenaptx --enable-aptx-hd --enable-ldac)

Available BT audio codecs: a2dp-source: SBC, AAC, aptX, aptX-HD, LDAC a2dp-sink: SBC, AAC, aptX, aptX-HD hfp-*: CVSD

Unfortunately, the same problem happens again, AAC is much better than SBC, fast foward just sometimes happened. (root@raspberrypi:/home/pi# arecord -D bluealsa:DEV=A4:CC:B3:7C:24:27 -f S16_le -c 2 -r 44100 test.wav) SBC: phone played likely 1min, record file is 8 seconds, and the file size is 1455212 AAC: phone played likely 1min, record file is 38 seconds, and the file size is 6879020

Maybe the better codec, the better record? l have no ideas... Although l have setup aptX, apX-HD, it doesn't work when l choose Qualcomm aptX or aptX-HD on my phone. (No capture device)

l will keep trying...

[Arika-Lei]

root@raspberrypi:/home/pi# ../configure --enable-systemd --enable-aac --enable-aptx --with-libopenaptx --enable-aptx-hd --enable-ldac --enable-cli --with-systemdbluealsaargs="-S -p a2dp-source -p a2dp-sink -c ldac -c aptx -c aptx-hd"

l try to configure like that, but aptx or ldac is still not effective

root@raspberrypi:/home/pi# bluealsa-cli info /org/bluealsa/hci0/dev_A4_CC_B3_7C_24_27/a2dpsnk/source Device: /org/bluez/hci0/dev_A4_CC_B3_7C_24_27 Sequence: 2 Transport: A2DP-sink Mode: source Running: false Format: S16_LE Channels: 2 Sampling: 44100 Hz Available codecs: SBC AAC Selected codec: SBC Delay: 15.0 ms DelayAdjustment: 0.0 ms SoftVolume: true Volume: L: 127 R: 127 Muted: L: false R: false

It seems like my phone doesn't have the ability of aptx and ldac, so l need to find other ways to solve the input stream.

[Arika-Lei]

l try to set my RPI 4's WIFI from 2.4GHz to 5GHz, and then everything becomes OK. l have no ideas about the relationship between the RPI 4's WIFI and the Bluetooth capture.

[Arika-Lei]

As my phone is the source mode, when l select APTX or APTX-HD on it, after bluealsa-aplay on my RPI 4, can't recognize the capture bluetooth devices. But when l choose SBC or AAC from my phone, my RPI 4 can show the bluetooth address of my phone. If bluealsa-h, APTX and APTX-HD are supported for a2dp-source and a2dp-sink. Besides, when l select APTX or APTX-HD on my phone, l can hear the music from the headphone connected with RPI 4.