Abstract: Since a delaying part (14) delays transmission of a video signal, the timing at which a decoded video signal is input into a multiplex processing part (16) matches the timing at which an analysis result from an encoded information analyzing part 13 is received by the multiplex processing part (16). It is, therefore, possible to perform processing for showing the quality level of a video on the same screen, and thus a large capacity memory is unnecessary.

Abstract: A monitoring method for monitoring a video/audio signal transmitted from a transmission source to a transmission destination has a step of storing the video/audio signal transmitted from the transmission source to the transmission destination repeatedly for a predetermined time period, a step of comparing a first characteristic amount extracted from the video/audio signal before the transmission and a second characteristic amount extracted from the video/audio signal after the transmission in real time, a step of determining an error occurrence when there is a difference of a predetermined value or more between the first characteristic amount and the second characteristic amount, and a step of transmitting the stored video/audio signal to a predetermined destination when an error occurrence is determined.

Abstract: A video/audio signal transmitted from a transmission source 10 to transmission destinations 20A and 20B is stored repeatedly for a predetermined time period. Thus, for example if the video/audio signal is overwritten at predetermined timing, it is sufficient to have a small storage capacity for the video/audio signal. Also, the video/audio signal on which an error has occurred remains without being overwritten at the time of determination that an error has occurred. Accordingly, by transmitting this signal to a predetermined destination, a detailed error analysis can be made promptly on the basis of the transmitted video/audio signal.