Recording Lossless - Drive Capacity Question

[Reape_28]

Hey guys, I just have a quick question I haven't been able to figure out the answer too. I'm just curious it anyone would know the answer. If I was recording lossless and had a 4TB hard drive, how many minutes or hours of video would I be able to record before I run out of space lol. I belive lossless is about 100MB/s but that's about it

I've tried searching Google but wasn't really able to find the exact situation

Any help would be appreciated, thanks!

 

[Suslik V]

It depends on codec and number of audio/video tracks.
General calculations are begins from the question "how lossless" is your final footage is. If it is 4:2:0 chroma and TV range video then it is about twice less than 4:4:4 chroma and PC range video. How many bits in each channel (8, 10, 16 etc)? How many bits, channels, sampling rate in audio?
Uncompressed numbers
Video:
{1920(width) x 1080(height) x 8(bits, R) +
1920(width) x 1080(height) x 8(bits, G) +
1920(width) x 1080(height) x 8(bits, B)} x 60(fps) = 2 985 984 000 bit/s = ~356 MiByte/s (RGB video), ~1.22 TiByte/hour
or
{1920(width) x 1080(height) x 8(bits, Y) +
960(width/2) x 540(height/2) x 8(bits, U) +
960(width/2) x 540(height/2) x 8(bits, V)} x 60(fps) = 1 492 992 000 bit/s = ~178 MiByte/s (YUV video, 4:2:0), ~0.61 TiByte/hour

Audio:
48000(Hz, sample rate) x 2 (channels) * 16 (bit per channel) = 1 536 000 bit/s = ~0.18 MiByte/s (1 track), ~0.00063 TiByte/hour
48000(Hz, sample rate) x 2 (channels) * 32 (bit per channel) = 3 072 000 bit/s = ~0.37 MiByte/s (1 track), ~0.00126 TiByte/hour

Compression ratio of the encoder can be from 2 to some huge number that depends on encoder and footage itself, so there you don't see right numbers in any threads on the forum and anywhere.

See also:

How to: Produce mathematically lossless video with alpha channel transparency in OBS Studio

Please note: if your goal is to produce visually lossless, high quality video, this isn't the place. With this, you'd be spending approximately 1932 gigabytes for 1 hour of recording at 1080p 60fps rawvideo (~4294967 Kbps). This has been...

obsproject.com

 

[koala]

Depending on the resolution you intend to record, it may be a spinning disk is not fast enough to permanently sustain the data rate required for recording lossless. The maximum data rate of a spinning disk is variable and depends on which cylinder data is being written: outer cylinders are faster than inner cylinders. Even if the data rate for the outer cylinders is sufficient, it may be not sufficient for inner cylinders.
A local SSD drive is recommended Not a spinning disk.

How to check how long your disk will last with your material:

• perform a representative test recording of the stuff you intend to record of about a minute
• in Windows Explorer, open the recording's file properties and look at the details tab. Locate the total bitrate. For a test recording of mine with resolution 1920x1080, it's shown 278839 kBit/s.
• to convert to kByte/s, divide by 8: 278839 kBit/s / 8 = 34854.87 kByte/s
• to convert kByte/s to MByte/s, divide by 1024: 34854.87 / 1024 = 34.038 MByte/s

This means, I'm writing about 34 MByte per second for this setup. If you want to check how long a 4 TByte disk lasts with that, keep in mind 4 TByte is 4,000 GByte is 4,000,000 MByte. So this disk will last 4,000,000 MByte / 34 MByte/s = 117,647 seconds
117,647 seconds are 117647 / 3600 = 32.68 hours or 32 hours 40 minutes.

If you're recording a different kind of footage or a different resolution or frame rate than me, you get a different data rate, so you need to make your own test. You cannot rely on my 34 MByte/s example for your situation.

 

[Reape_28]

Thanks for the info guys. I should have given more detail. I'd most likely be using the UT video codec that OBS uses for lossless and be recording at 1080/60fps 4.2.0. I've done a few tests and depending on the game my average bitrate is usually between 80-100MB/s using default settings which I'm fine with