What does this equation mean?

Video inherits the same per-tile arithmetic and multiplies it by time. Google is again the most specific vendor to check, because Gemini’s video-understanding documentation breaks the rate down by component: at default media resolution, each sampled frame (taken at one frame per second) costs about 258 tokens and the accompanying audio track costs about 32 tokens per second, for a documented total of “approximately 300 tokens per second of video.” At the model’s low-resolution setting, the same second costs about 100 tokens — 66 for the frame plus 32 for audio [ 6 ] . In the notation above, that is $N_{\mathrm{tok}}(\mathrm{video}) = t \left( f \cdot \tau_{\mathrm{frame}} + \tau_{\mathrm{audio}} \right)$. where t is duration in seconds, f the sampling rate, and $\tau_{\mathrm{frame}}$ , $\tau_{\mathrm{audio}}$ the per-frame and per-second-of-audio token costs Google publishes. A minute of default-resolution video comes to roughly 18,000 tokens — about 2.7 cents at Gemini 3.5 Flash’s input rate, or about 1.35 cents at Gemini 3.7 Flash’s [ 6 , 4 ] . That is understanding a minute of footage: having the model watch it once and answer questions about it.