A receiving device performs an action that results in a corrective measure being taken to address a picture quality issue detected in real time in the frames currently being displayed on a television or other device. The receiving device or a remote system compares indications of video frames currently being displayed to stored video frames for that program to detect macroblocking or a frozen video frame. The macroblocking or a frozen video frame may also or instead be detected by image analysis of the frames currently being displayed. If macroblocking or a frozen video frame is detected in the frames currently being displayed, the set-top box may switch to an alternative video source, change to a standard definition channel broadcasting the same video program or perform other corrective actions.