Last week we demonstrated how simple 4fps thumbnail contact sheets offer an incredibly powerful way of previewing unenriched television news. In that example we looked at a single broadcast from state-owned television channel RUSSIA1. Here we repeat this process for several additional programs across three Russian channels to explore how it performs. For each broadcast, we compute three different contact sheets:
- 160 Pixel 1/4FPS. The broadcast is sampled at a fixed framerate of exactly one frame every 4 seconds. Each frame is 160 pixels wide, making it compact enough to easily survey an entire broadcast in seconds, though fine detail is lost and text becomes illegible.
- 500 Pixel 1/4FPS. The broadcast is sampled at a fixed framerate of exactly one frame every 4 seconds. Each frame is 500 pixels wide, making it difficult to rapidly survey the broadcast, but making text legible. Segments of interest from the 160 pixel contact sheet can be referenced here to see fine detail like text.
- 160 Pixel Avg Frame. FFMPEG's built-in thumbnail generation filter batches the video into sequences of 100 frames and for each batch computes the color histogram of each frame, averages them together to derive the average histogram of that sequence, then selects the frame that is closest to the average and thus most "representative" of that sequence of frames. This enhances the temporal representativeness of the fixed frame rate previews by largely filtering out isolated interstitial frames or motion bursts, ensuring that for each sequence of 100 frames, the thumbnail selected best represents the average imagery of that sequence.
Below you fill find a small selection of Russian television news broadcasts and the three contact sheets described above.
1TV: April 26, 2022 3:30-4:01AM MSK
1TV: April 26, 2022 4-4:31AM MSK
NTV: April 25, 2022 4:30-5:00PM MSK
NTV: April 25, 2022 7:00-7:30PM MSK
RUSSIA1: April 25, 2022 5:30-6:00PM MSK
RUSSIA1: April 25, 2022 6:00-6:31PM MSK
