I have a Samsung Galaxy S21-U running Android 14 and Termux 0.118.1 (retrieved from F-Droid on 2024.08.22) with TigerVNC 1.10.1-41. TigerVNC and associated required packages retrieved via apt in termux: I followed these steps to bring up an xfce4 desktop environment via tigervnc.

Clear instructions for getting sound output are harder to find.

1. The following solutions successfully played MP3 files over USB-C speakers:
   • The command play-audio from this answer (mpg123 and play produce no output, but see [2] below);
   • These instructions on reddit for the mpv command;
   • I cannot get output over the phone speakers from either of the above.
2. The VNC subset of this answer does not work for me
   • A virtual pulseaudio sink auto_null.monitor exists.
   • The commands play and mpg123 seem to attach to this sink.
   • With the above inputs attached, the sink auto_null.monitor switches state from SUSPENDED to RUNNING.
   • With audio playing, the xfce4 volume control panel shows the volume fluctuating.
   • No sound is emitted over either the phone or USB-C speakers.

Further research

This reddit thread contains some links.

• There is a comment which others say does not work. For me, specifically, the error from those commands is User-configured server at 127.0.0.1, refusing to start/autospawn. I gather this is connected to the existing configuration set to achieve [1] and [2] above, but am not sure about the safe/correct steps to redress it.
• There is a link to LinuxDroidMaster's Termux-Desktops github. The approach I'm using is consistant with what they call a termux native desktop. I couldn't find mention of sound beyond a passing pkg install pulseaudio line, but let me know if there's more there.
• There is a link to these instructions, which seem to assume the proot installation approach has been followed. It seems to download a .sh file, but its content appears to be binary and I do not know how to extract it into a human-readable form to understand what it is doing.

This reddit user is strugging with a chroot termux setup

• Their posted solution may contain important clues even though I am not using a chroot setup. I get the same User-configured server at 127.0.0.1, refusing to start/autospawn error when I enter their commands, but presumably I need to go back and undo something in the setup for failed solutions [1] and [2]] to tidy things up.

Another reddit thread

• The only reply suggests using termux-media-player play from the termux-api package. This produces no sound for me, from either the phon or USBC speaker, when run from either the termux terminal or the xfce4 VNC session.

Pursuing the User-configured server at 127.0.0.1, refusing to start/autospawn error,

• I ran apt remove pulseaudio --purge, noted the packages this would remove in the console output of said command, and then reinstalled all these packages along with pulseaudio.
• This cleared user edits to configuration files in ~/../usr/etc/pulse/. I browsed for other suspicious *rc* and *profile* file names that might contain leftover configuration and found none.
• I opened a fresh shell to clean out any export VARNAM=FOO cruft.
• pulseaudio --start runs.
• I typed pulseaudio -k and export PULSE_SERVER=127.0.0.1
• Now pulseaudio --start prints the (presumably desired) refusing to start/autospawn error.
• I returned to termux and ran pactl load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1 auth-anonymous=1
• At this point, /u/allanrps reported

  You should now be able to return to the chroot environment and play audio. The clients will connect to the pulse server running in termux and you will have sound!

  But, no sound is heard (although pulseaudio controls register audio being sent).

Edit 1 2024.08.23

I suspect that:

• Even when given permissions to play audio, the Termux app does not have access to the phone's speakers (unless perhaps on rooted devices with chroot?). It can only natively export sound over USB-C audio devices.
• Most of the tutorials for the VNC desktop environments use pulseaudio, and the instructions above are not for routing pulseaudio output to external USB-C speakers.
• The commands play-audio and mpv do something else to access USB-C speakers via termux (bypassing pulseaudio), which is why they work.
• There is probably a way to get apps talking to pulseaudio in the xfce4 session to play to USB-C speakers as well, but exact methods are TBD.
• In principle there is no reason a pulseaudio server with access to the phone speakers could not be incorporated into the termux app. Indeed, I imagine there may be forks or newer versions that do this. But, it is not (AFAICT) implemented in the F-Droid version.
• For playback through phone speakers using termux on a non-rooted device, one needs a third Android app to serve a network pulseaudio sink, and connect termux to this as if it were a remote machine. I need to ensure that the pulseaudio client settings in termux are set correctly to match the pulseaudio server app started on Android. I will attempt this with PulseAudio Rtp Receiver version 1.0.6 .

These are the default server settings for PulseAudio Rtp Receiver version 1.0.6 installed from F-Droid on 2024.08.23:

IP: 224.0.0.56
Port: 4010
MTU: 320
Max Latency (ms): 300
Channel Count: 2
Channel Mask: 0
SampleRate: 48000
framesPerBurst: 192

That default IP 224.0.0.56 is probably nonsense. I changed it to 127.0.0.1 in the PulseAudio Rtp Receiver GUI and restarted the server. Per this reddit comment, I tried running

export PULSE_SERVER=224.0.0.1:4010

(with and without the port), but it did not work. Neither did the pactl load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1 auth-anonymous=1 command from [2]. I got Could not open device: error 5 when subsequently using the play command for all of the above.

Based on the first comment reply here I added the following lines to /data/data/com.termux/files/usr/etc/pulse/default.pa:

load-module module-null-sink sink_name=rtp format=s16be channels=2 rate=48000 sink_properties="device.description='RTP Multicast Sink'"
load-module module-rtp-send source=rtp.monitor destination_ip=127.0.0.1 port=4010 loop=1

I started a fresh shell and ran

pulseaudio -k
pulseaudio --start
play ......

With some success, I can now see PulseAudio Rtp Receiver receiving data! Still, no sound. As it turns out, PulseAudio Rtp Receiver does not have permissions to access speakers, has never requested it, and has no way to trigger a request for this permission. Well, its FOSS. Getting closer!

Question

I want to see if I can get the pulseaudio command play to emit over the phone speakers. Has anyone achieved this?