How to prevent a pop noise when video playback starts/stops when i.MX6Q output audio to HDMI.

[satoshishimoda]

Hi community,

I have a question about i.MX6DQ Yocto BSP.

Pop noise is occurred when start video playback and finish playback if the video and audio is output to HDMI display.

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[Board]

MCIMX6Q-SDB

[BSP]

L3.10.17_1.0.0-ga

[Procedure]

1. Set bootargs "video=mxcfb0:dev=hdmi,1920x1080@60,bpp=32" to use HDMI display.

2. Boot L3.10.17_1.0.0-ga BSP.

3. Play a video with following command.

gplay test.mp4

4. Pop noise is output from HDMI display.

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[Question]

Could you let me know how to prevent this pop noise?

Best Regards,

Satoshi Shimoda

[jamesbone]

Hello Satoshi San,

Is the Audio Noise appear in the headphones? because there is no audio output on the HDMI? right? 

[satoshishimoda]

Hi jamesbone,

> Is the Audio Noise appear in the headphones?

I tested the following routes, and the audio noise appear both case.

[Route 1]

MCIMX6Q-SDP --- HDMI cable ---> HDMI display ----> speaker in HDMI display

[Route 2]

MCIMX6Q-SDP --- HDMI cable ---> HDMI display --- audio cable ---> headphone

> because there is no audio output on the HDMI? right?

I don't understand what is root cause well, but maybe so.

I think this issue cannot be resolved by the circuit in HDMI display, can it?

So could you give me advice to prevent this noise?

Best Regards,

Satoshi Shimoda

[saurabh206]

Hi Satoshi,

Did you able to fixed the Pop noise issue?

[satoshishimoda]

Hi Saurabh Patel,

Now, we always play "mute" audio and mix it by ALSA after power up Linux.

This "mute" prevents pop noise and not prevent other audio playback.

Best Regards,

Satoshi Shimoda