Adapter to power motorcycle-mounted camera

Device (preferrably existing): Adapter for external DC power source for motorcycle-mounted camera

I am probably one of many people who want their motorcycle-mounted video camera to be externally-powered from the 12V motorcycle battery and not from the camera's battery. If anyone knows of a product or wants to develop one, please reply.

My specifications:
Camera: Canon PowerShot S410 Camera
Its battery: NB-1LH, 3.7V, 840mAh (Li-ion)
Its auto charger (recharges the battery but does not interface the camera!): CBC-NB1

Links:
Canon PowerShot S410 Camera
Canon Powershot-S410 Review: Overview

Electronic switch-mode DC to DC converters (more efficient than linear converter)
DC-to-DC converter - Wikipedia, the free encyclopedia

Others:

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https://www.electro-tech-online.com/threads/camera-external-power-supply.30310/

evCommuter

The simplest way would probably be to use an LM317 or equivalent linear adjustable voltage regulator. Connect the input pin to the motorcycle positive battery terminal and the ground pin to the negative battery terminal. Then set the output to 3.7V and connect the output pin to the positive connector in the camera's battery compartment and connect the negative connector in the camera's battery compartment to the LM317 ground pin. You would probably benefit from some caps at the input and output of the 317 as well.