Switch to PortAudio

[Cuda-Chen]

Switch to PortAudio for cross-platform and cross backend compatibility.

Yet, there are two known limitations for current sound playback implementation:

1. The sound may produce stutter effect.
2. You cannot play sound twice or the device will crash thus
   whole emulator crashes.

Testing

Preparation

1. Run make build-image to build Linux Kernel image and root filesystem.

Test Cases

play white noise

test procedures

1. Execute speaker-test in emulator shell.
2. Check the host speaker.

expected results

1. A white noise should be played by host speaker in the first round while speaker-test is executing.
2. The emulator should crash after the second round of playing white noise.

play sequence sound

test procedures

1. Execute aplay /usr/share/sounds/alsa/Front_Center.wav in emulator.
2. Check the host speaker.
3. Execute aplay /usr/share/sounds/alsa/Front_Center.wav in emulator.

expected results

1. A sound with "Front Center" speaking with stutter effect should be played in step 2.
2. The emulator should crash after step 1.

Summary by Bito

This pull request integrates PortAudio to enhance cross-platform audio playback, replacing the previous CNFA submodule. It updates the Makefile for better build configurations, addresses issues like sound loss and system crashes, and improves PCM stream handling and compatibility, while also updating documentation.

Unit tests added: False

Estimated effort to review (1-5, lower is better): 2

[jserv]

You should explain the motivation and benefit for the migration of PortAudio.

[jserv]

Build failure:

  LD	semu
/usr/bin/ld: cannot find -lpulse: No such file or directory
collect2: error: ld returned 1 exit status

[Cuda-Chen]

Build failure:

  LD	semu
/usr/bin/ld: cannot find -lpulse: No such file or directory
collect2: error: ld returned 1 exit status

Thanks for the reminder!
I am still working on this issue.

[jserv]

Prepare the instructions l for testing the PortAudio-based virtio-snd backend, including preparation of the Linux kernel image and root filesystem. The goal is to deliver the preliminary work that can be shared with and potentially expanded by additional contributors.

[Cuda-Chen]

Prepare the instructions l for testing the PortAudio-based virtio-snd backend, including preparation of the Linux kernel image and root filesystem. The goal is to deliver the preliminary work that can be shared with and potentially expanded by additional contributors.

I have added the test procedures in "Testing" section located in the first comment.

[jserv]

You cannot play sound twice or the device will crash thusnwhole emulator crashes.

Have you resolved this issue?

[Cuda-Chen]

You cannot play sound twice or the device will crash thusnwhole emulator crashes.

Have you resolved this issue?

I haven't resolve this issue, yet.

Should we resolve the issue in this PR?

[jserv]

Should we resolve the issue in this PR?

Yes, let's determine the root cause and resolve the issue causing crash.

[jserv]

Use <portaudio.h> instead.

[jserv]

Can you move the common part into an inline function?

[jserv]

@Cuda-Chen, Why did you enable Enable hrtimer in ALSA configurations?

[Cuda-Chen]

@Cuda-Chen, Why did you enable Enable hrtimer in ALSA configurations?

To make sure whether the hrtimer resolve the stuttering and sending invalid stream ID issues.

[Cuda-Chen]

Hi @jserv , I would like to summarize the current progress:

1. For stuttering effect, the root case remains unknown. It seems that the sound driver just sends the sound with stuttering effect.
2. For crash issue, it is confirmed that the sound driver sends the PCM frames with invalid stream ID. I need to come up with a solution (the current attempt needs more work). As a consequence, you may mark this PR into a draft PR.