No sound for 2 seconds at the beginning of AVI video playback

This is normal. The HDMI default setting on the product (Default: Auto) selects the best picture frame for the TV. If the AVI video picture frame is not the best match for the TV, the product carries out an initialization procedure to select the best picture frame for the TV at the start of AVI video playback. This initialization takes around 2 seconds and the sound is muted.