Videotoolbox: what’s the downsides?

[FlyingTexan]

I have a large library of media and I’m starting to hit my storage limits. I also have a spare m4 base model Mac mini sitting in a drawer that doesn’t have anything to do so was debating connecting it to my router and letting it run on my library.

The question for me is what are the downsides of videotoolbox? If I have a remux 4k HDR 10bit file and I want to encode it are there pitfalls? Can it handle dark scenes, film grain, tone mapping well? I’m also curious what file sizes would look like if I’m going strictly for transparent video (VMAF 97+)?

I can’t seem to find any numbers for fps with software encoding, I know it’s vastly slower but no idea where it winds up.

 

[bogdanw]

See "Videotoolbox or CPU" https://forums.macrumors.com/threads/videotoolbox-or-cpu.2458215/

 

[FlyingTexan]

I'd read through that prior to posting. Doesn't really address the downsides of videotoolbox (I get file size isn't quite as small) but I don't see any numbers by anyone anywhere. What kind of fps I could expect, etc.

 

[!!!]

Can it handle dark scenes, film grain

Not well, in my experience.

I’m also curious what file sizes would look like if I’m going strictly for transparent video (VMAF 97+)?

About the same or worse than the remux itself. It's only really desirable to use hardware encoding if you are trying to change video formats for compatibility purposes, eg. I need H.264 for an older computer so I convert using VTB onto a spare HDD. I don't need to worry about size I'm only concerned with doing it quickly.

Doesn't really address the downsides of videotoolbox (I get file size isn't quite as small) but I don't see any numbers by anyone anywhere.

I don't have any numbers because I don't seriously encode using videotoolbox, but you will get markedly worse filesizes compared to using x265. I suspect no one else has numbers because trying to line up quality between VTB and CPU is time consuming and there's no benefit, if you are trying to meet some quality goal at some file size, use CPU. It's not even worth looking into hardware encoding.

What kind of fps I could expect

Video toolbox will give you higher FPS compared to CPU encoding, but I don't see how that's worth it unless your goal is to encode videos quickly, rather than to save space.

 

[FlyingTexan]

Wow didn't realize the file sizes were that kind of problem. But generally with something like a m4 doing cpu encoding could it do realtime?

 

[kitKAC]

Can it handle dark scenes, film grain, tone mapping well? I’m also curious what file sizes would look like if I’m going strictly for transparent video (VMAF 97+)?

Why not encode two files and compare them (one with videotoolbox and the other without)?

 

[FlyingTexan]

Why not encode two files and compare them (one with videotoolbox and the other without)?

Because I’m no expert with it and it was a lot less effort and a lot less time to just ask

 

[bzgnyc2]

Wow didn't realize the file sizes were that kind of problem. But generally with something like a m4 doing cpu encoding could it do realtime?

Unlikely. There are a lot of variables but encoding 4K video with H.265 is likely going to be in the range of 5fps on a base M4. The reason for hardware encoders is that they give 5-10x speedup. Just with some loss of quality and/or file size efficiency all else being equal.

If you have hundreds of movies in older formats, expect transcoding them to H.265 in software on an M4 will take months. Alternatives include accepting the tradeoffs of hardware encoding or perhaps offloading this to cloud resources (where you could have a flock of 4 core servers each transcoding a movie in parallel).

 

[bogdanw]

I also have a spare m4 base model Mac mini sitting in a drawer that doesn’t have anything to do so was debating connecting it to my router and letting it run on my library.

Sell the Mac mini, buy more storage 🙂
6TB $194 https://www.amazon.com/Seagate-Enterprise-Capacity-ST6000NM0095-7200RPM/dp/B01CG0DBXE/
3.5" enclosure ~$25 https://www.amazon.com/RSHTECH-Enclosure-Upgraded-Aluminum-External/dp/B0D45F4DT7/

 

[phrehdd]

I can't argue the use of this software but sure seems easier to get more physical media to store files. External drives of all sorts or NAS or DAS. I store smaller video on external drives and large files or archived discs on NAS. Has worked great for me and I keep the quality of the files for playback (video and audio).