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Equation 7 · Part 5 · What Multimodal AI Actually Costs, Modality by Modality

Symbol tau_audio

Ntok(video)=t(f⋅τframe+τaudio),N_{\mathrm{tok}}(\mathrm{video}) = t \left( f \cdot \tau_{\mathrm{frame}} + \tau_{\mathrm{audio}} \right),
τaudio\tau_{\mathrm{audio}}

What this part means

the per-frame and per-second-of-audio token costs Google publishes.

Its job in the formula

tauau_audio is one of the signed contributions combined to compute the quantity on the left.

Where the article explains it

where t is duration in seconds, f the sampling rate, and τframe\tau_{\mathrm{frame}} , τaudio\tau_{\mathrm{audio}} the per-frame and per-second-of-audio token costs Google publishes.

The passage around this formula

…the same second costs about 100 tokens — 66 for the frame plus 32 for audio [ 6 ] . In the notation above, that is Ntok(video)=t(f⋅τframe+τaudio)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 τframe\tau_{\mathrm{frame}} , τaudio\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…

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the surrounding passage

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