My iPod has audio noise when playing videos

I used HandBrake to convert my videos into MP4 format, which should be playable on my iPod nano 7th generation. The video imports and plays normally, but there's an issue with the left audio channel where it produces random noise.

I initially thought the problem was with the video file itself, but when I connected my iPod nano 7 to my computer via iTunes and played the video stored on the iPod's internal memory, everything played back perfectly without any noise.

Additionally, when I play music and quickly drag the progress bar, I notice a very brief noise, which is so short that it's almost unnoticeable unless you listen carefully.

The video format details are as follows: H.264, 720 x 576, 30 fps, Baseline. The audio format details are: AAC-LC, 128kbps, 48kHz.

I've checked my headphones and they are working fine. I've also tried restarting my iPod, using different format conversion software, and even importing the video using another computer, but the problem still persists. =(

Currently, my iPod hasn't suffered any severe impacts or water damage, and the battery hasn't been replaced since I bought it.

I suspect the issue might be due to battery aging, as when charging, it doesn't show the charging process animation but directly displays the fully charged state animation (although this could be by design). I can't think of any other reason for this problem. I'm hoping someone can help me resolve this issue. :)