USBX Audio - Speaker does not play true stereo

[audio]

I am using a UX_Device_Audio2.0-based project on H7. 

1. When I play a stereo file (actually dual mono), the right channel plays correctly, but the left channel contains a mix of left + right.
2. When I play mono file, the right channel is much louder while the left is extremely quiet.

Could this be a codec configuration issue (mixer/settings), a USB audio packet scheduling problem, or something else? I can't seem to find a fix yet. 

[LCE]

> Could this be a codec configuration issue (mixer/settings), a USB audio packet scheduling problem, or something else?

Yes, yes, and yes.

Hard to guess without any info - except that it doesn't work.

[audio]

LOL - that's funny, thanks for the laugh.

This can be tested with base example from STM32 - I just tested it on H753i-eval board.

[LCE]

... which surely everybody has and uses it that way?

;) 

At least we have one more info now.

[AScha.3]

>This can be tested 

- I dont have this board.

- what sample rate you set ? Try 48k 16b stereo. (USB /UAC1 only working correct at 48k...afaik. Maybe UAC2 can do more...but i never tried, lost interest /too much to learn and check and program then )

- what you set/tried at host side ? + host is...Win/mixer , Linux/Alsa , pulse.., pipe ..or ?

[FBL]

Hi @audio 

Thank you for providing your feedback regarding this issue. 

Did you play test signals from PC :a left-only /right-only sine, a dual-mono tone ?..

 To better isolate the root cause, do you reproduce using this example Projects\STM32H743I-EVAL\Examples\SAI\SAI_AudioPlayback and can you log a few frames of what you receive into a small array and inspect via debugger or UART . 

Your symptoms are more likely coming from codec mixer /analog routing or digital channel mapping (USB buffer to SAI) rather than USB packet scheduling.

[audio · Accepted solution]

Hello @FBL 

The issue was the cable. It was mixing two channels together thus not giving a true stereo output. 

Once I changed the cable, it worked as normal. 

Thanks.