Formula
The two streams share the card:
seconds = card bytes × 8 / (video Mbps × 1,000,000 + audio kbps × 1,000)
The video duration page uses one bitrate for a file that already exists. This page plans a card.
Assumptions
- The card size is decimal gigabytes and is empty.
- Both bitrates stay constant.
- Audio may be zero.
Worked example
A 64 GB card at 50 Mbps of video and 320 kbps of audio records for 2:49:35.
Input definitions
- Video bitrate
- Megabits per second of the picture.
- Audio bitrate
- Kilobits per second of the sound, added to the picture.
Limitations
This is a planning figure from the numbers you type. It is not a measurement of a network, a camera, a printer, or a power supply.
Questions
Why not add 320 to 50?
They are different units. 320 kilobits is 0.32 megabits, and the formula adds them after converting.
What if the file is already recorded?
Use the duration page with the file size and one average bitrate.