Testing system for a video and audio reproduction system , comprising: a data source with video and audio data for reproduction by the video and audio reproduction system , the video and audio data comprising unique marks (5, 65 - 67, 7, 46 - 53, 71 - 73) in every video frame (4, 30 - 37, 62 - 64) and every audio frame (6, 38 - 45, 68 - 70) ; a recording unit , configured to record a video stream and an audio stream generated by the video and audio reproduction system by reproducing the video and audio data ; and a test processor , configured to extract the unique marks (5, 65 - 67, 7, 46 - 53, 71 - 73) from the recorded video stream and the recorded audio stream , and to verify if respective unique marks (5, 65 - 67, 7, 46 - 53, 71 - 73) of simultaneous video frames (4, 30 - 37, 62 - 64) and audio frames (6, 38 - 45, 68 - 70) have been recorded by the recording unit simultaneously; wherein an audio frame (6, 38 - 45, 68 - 70) is an audio sequence with the length of a respective video frame (4, 30 - 37, 62 - 64) and the unique marks (7, 46 - 53, 71 - 73) in the audio frames (6, 38 - 45, 68 - 70) comprise a sinusoidal sound wave of a respective frequency; wherein the frequencies of the sinusoidal sound waves range from a minimum frequency to a maximum frequency; wherein the frequencies of the sinusoidal sound waves of two consecutive audio frames (6, 38 - 45, 68 - 70) are spaced apart by a first threshold value; wherein the frequencies of the sinusoidal sound waves increase sequentially by the first threshold value until the maximum frequency is reached and then fall back to the minimum frequency plus a second threshold value, and wherein the second threshold value increases with every repetition of the frequency sequence by its starting value. a data source with video and audio data for reproduction by the video and audio reproduction system , the video and audio data comprising unique marks (5, 65 - 67, 7, 46 - 53, 71 - 73) in every video frame (4, 30 - 37, 62 - 64) and every audio frame (6, 38 - 45, 68 - 70) ; a recording unit , configured to record a video stream and an audio stream generated by the video and audio reproduction system by reproducing the video and audio data ; and a test processor , configured to extract the unique marks (5, 65 - 67, 7, 46 - 53, 71 - 73) from the recorded video stream and the recorded audio stream , and to verify if respective unique marks (5, 65 - 67, 7, 46 - 53, 71 - 73) of simultaneous video frames (4, 30 - 37, 62 - 64) and audio frames (6, 38 - 45, 68 - 70) have been recorded by the recording unit simultaneously; wherein an audio frame (6, 38 - 45, 68 - 70) is an audio sequence with the length of a respective video frame (4, 30 - 37, 62 - 64) and the unique marks (7, 46 - 53, 71 - 73) in the audio frames (6, 38 - 45, 68 - 70) comprise a sinusoidal sound wave of a respective frequency; wherein the frequencies of the sinusoidal sound waves range from a minimum frequency to a maximum frequency; wherein the frequencies of the sinusoidal sound waves of two consecutive audio frames (6, 38 - 45, 68 - 70) are spaced apart by a first threshold value; wherein the frequencies of the sinusoidal sound waves increase sequentially by the first threshold value until the maximum frequency is reached and then fall back to the minimum frequency plus a second threshold value, and wherein the second threshold value increases with every repetition of the frequency sequence by its starting value. <EOS>