Looking to record a world record stream, need help with file size

Hello, we are looking to record an upcoming charity world record stream, and if it all goes well the recording will be roughly 40 hours long. We are aware that this file will be extremely large. Does anyone know anything we can do to try and reduce file size? We want to record in the best quality we can while keeping the file size reasonable. We have a 5TB external hardrive we will be using to save the file on.



Active Member
If you record what you're streaming (using the "use stream encoder" encoder setting for recording), you're recording exactly what is sent for streaming. This is usually constant bitrate (CBR), so you can compute exactly how big that file will be:

size = duration * bitrate

For example, if you're streaming 40 hours with bitrate 10000 (which is 10000 kbps):
size = 40 hours * 10000 kbps
which is:
size = 40 * 3600 seconds * 10000 kbit / second
1 byte is 8 bit, so 10000 kbit/second are 10000 / 8 byte / second = 1250 kB/second.
size = 40 * 3600 seconds * 1250 kB/second
size = 40 * 3600 * 1250 kB
size = 180.000.000 kB = 180.000 MB = 180 GB

If you record with a second encoder session (use Nvenc or x264 as encoder for recording with a quality based rate control such as CQ or CRF or simply the simple output mode, instead of (use stream encoder)) that results in a average bitrate of perhaps 50000, multiply the file size accordingly. The actual average bitrate for quality based rate controls depends on the recording settings and on the footage, so you should do test recordings and see what average bitrate actually comes out of the test video.


You might look in the Resources section here for a script that can break (stop-start) the recordings at set intervals. You could then find a program that watches the folder your recordings are created in and move them to a large backup drive or network storage as each is completed. The only downfall is a slight glitch at the file breaks when you recombine them in a video editing program.


I shudder at the thought of editing a 180GB file. Many small files would be much easier to handle.