Random black frames during looping playback

This is most likely due to using non-approved/tested SD cards. Some SD cards have inconsistent timing when reading sectors, which combined with the lack of significant buffers and processing power of the embedded DMXking products can cause these artifacts. For error-free operation you should only use cards from the approved list. As a workaround you can enable the option "Hold Last Frame", but note that there will still be a short delay.