SK-AM62A-LP: Continuous Audio Playback Fails

Hello Suren. Thank you for your help, but we are not trying to play sound files at the same time. We are trying to play one file and then immediately play the next one. 

That is what the aplay example is doing. It plays one file and then immediately plays the next one using the same device.  This fails on the AM62x with the 6.1 kernel.

You should be able to reproduce this error on your EVM.  My expectation is that it would play the sound and then play it again without the underflow error.

-Bob

Hi Bob,

Are you testing with the latest SDK 9.1 release for AM62A?

I just ran this command on my AM62A board and didn't see any issues playing files one after the other with a single aplay command.

root@am62axx-evm:/home# aplay piano2.wav piano2.wav piano2.wav piano2.wav 16_48k_PerfectTest.wav piano2.wav 16_48k_PerfectTest.wav piano2.wav
Playing WAVE 'piano2.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Playing WAVE 'piano2.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Playing WAVE 'piano2.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Playing WAVE 'piano2.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Playing WAVE '16_48k_PerfectTest.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Playing WAVE 'piano2.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Playing WAVE '16_48k_PerfectTest.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Playing WAVE 'piano2.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
[ 9980.643752] ti-udma 485c0100.dma-controller: chan1 teardown timeout!
root@am62axx-evm:/home#

Best Regards,

Suren

Suren,

Testing on the AM62A evm (SK-AM62A-LP) with a freshly flashed SDK 9.1 image.

Note that i'm using the alsa Noise.wav since it's already on the filesystem. Not sure where to get your piano2.wav or 16_48k_PerfectTest.wav

root@am62axx-evm:/opt/edgeai-gst-apps# uname -a
Linux am62axx-evm 6.1.46-g247b2535b2 #1 SMP PREEMPT Wed Dec  6 17:54:04 UTC 2023 aarch64 aarch64 aarch64 GNU/Linux
root@am62axx-evm:/opt/edgeai-gst-apps# aplay /usr/share/sounds/alsa/Noise.wav /usr/share/sounds/alsa/Noise.wav /usr/share/sounds/alsa/Noise.wav /usr/share/sounds/alsa/Noise.wav
Playing WAVE '/usr/share/sounds/alsa/Noise.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
Playing WAVE '/usr/share/sounds/alsa/Noise.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
[   82.906866] davinci-mcasp 2b10000.audio-controller: Transmit buffer underflow
underrun!!! (at least 0.349 ms long)
[   82.936810] davinci-mcasp 2b10000.audio-controller: Transmit buffer underflow
underrun!!! (at least 0.029 ms long)
[   82.978049] davinci-mcasp 2b10000.audio-controller: Transmit buffer underflow
Playing WAVE '/usr/share/sounds/alsa/Noise.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Mono
aplay: set_params:1416: Unable to install hw params:
ACCESS:  RW_INTERLEAVED
FORMAT:  S16_LE
SUBFORMAT:  STD
SAMPLE_BITS: 16
FRAME_BITS: 16
CHANNELS: 1
RATE: 48000
PERIOD_TIME: 125000
PERIOD_SIZE: 6000
PERIOD_BYTES: 12000
PERIODS: 4
BUFFER_TIME: 500000
BUFFER_SIZE: 24000
BUFFER_BYTES: 48000
TICK_TIME: 0
[   84.005417] ti-udma 485c0100.dma-controller: chan1 teardown timeout!

Download link: dr-download.ti.com/.../tisdk-edgeai-image-am62axx-evm.wic.xz

Hi Jonathan,

I was able to reproduce the issue when I removed my /etc/asound.conf file. Just to let you know if I have the /etc/asound.conf with these details, I can run any number of times without any issues. 

Contents of the /etc/asound.conf:

pcm.!default {
        type plug
        slave.pcm "dmixer"
}

pcm.dmixer  {
        type dmix
        ipc_key 1024
        slave {
                pcm "hw:0,0"
                period_time 0
                period_size 64
                buffer_size 9600
                rate 48000
        }
        bindings {
                0 0
                1 1
        }
}

ctl.dmixer {
        type hw
        card 0
}

Best Regards,

Suren

Suren, thank you for your additional attention. We will do some tests with the asound.conf change and I will follow-up here.

Suren Porwar said:

I was able to reproduce the issue when I removed my /etc/asound.conf file. Just to let you know if I have the /etc/asound.conf with these details, I can run any number of times without any issues. 

Contents of the /etc/asound.conf:

Thanks, adding the asound.conf does make the command succeed.  Above you mentioned something about having the files mixed together before playing. What does this mean and why is this necessary?  I would have thought aplay should be able to stop and start playing a different file without having to mix them.

Any idea if the asound.conf will have any effect on audio played through QT, we will dig into it ourselves but curious if you knew. My grasp on alsa and pulseaudio is pretty rusty.

Hi Jonathan,

If you don't want to use the asound.conf approach to specify the period-size and buffer-size, you can apply the below patch in the linux kernel, compile and rebuild the kernel Image. 

I have verified with the below patch, I was able to run multiple files without any issues.

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/791/1581.underrun_5F00_crash_5F00_fix.patch

Hope this helps.

Best Regards,

Suren

I tested the patch and it does allow aplay to play multiple files in a row.

The patch is nice and simple, though I wonder why it's in common code and why this issue doesn't crop up with other platforms like the 57x. I suppose there could be a regression in the kernel, since I don't have a 5.10/6.1 kernel to test on my 57x right at this moment.