Question

Question 3 Coding of a video
Answer this question using your chosen YouTube video.
a) For the chosen video, is there a lot of temporal redundancy between the frames?
In your opinion, does the temporal redundancy in this video make it possible to obtain a
very high compression? Explain assuming compression with MPEG, as seen in
the lesson.
b) Is the chosen video encoded in progressive format? Explain your answer.
c) (1 point) Does the video contain block effects? Explain why there is presence or
absence of block effects.

Answer 1

1. Temporal redundancy is present when there is large similarity between two successive frames of a video. Yes, for the chosen video , there is a significant temporal redundancy between frames. high compressing a video with lot of temporal redundancy is possible(although other features like spatial redundancy, spectral redundancy etc should also be considered). There are some non-redundant information to which human eyes are quite insensitive. Human eyes do not distinguish between two video sequences one of them encoded at 30 frames per second and the other at 60 frames per second. In addition, they are more sensitive to the variation of luminance than chrominance information. Video encodres exploit this fact .

Starts with an I-frame • Ends with frame right before next I-frame • “Open” ends in B-frame, “Closed” in Pframe – (What is the difference?) • MPEG Encoding parameter, but ‘typical’: – I B B P B B P B B I – I B B P B B P B B P B B I • Why not have all P and B

b. When the video is paused and zoom during motion, and then viewed frame by frame, there appears comb like pattern, suggestiing that the video is interlaced.

c.Yes there is block effect as in cases of high compression ratios, the BDCT method results in the block boundaries being visible in the reconstructed image.