Question / Help New GTX 1660 ti- NVENC H265 files are larger not smaller

N

NS_0607

New Member
I'm using OBS 23.2.1 on a Win 10 machine with Ryzen 7-1700 and 16 GB ram. I installed my new GTX 1660 ti with NVIDIA driver set 430.86 tonight for OBS recording (I don't stream/game). and am not seeing smaller files using the NVENC 265 codec. Using the old GT730 card and NVENC H.264 (new) codec I was getting file sizes around 480MB for a 24 minute show. I use another program called MCEBuddy (MCEB) to transcode them to HEVC and add show titles which drops them down to around 230 MB- what I was trying to do using the ti was to get a small file so it would not have to be processed twice- I can run it thru MCEB w/o transcoding.

I followed the instructions I found for using the H265 NVENC- under the recording tab, custom, ffmpeg, then MP4 container and then the hevc_nvenc(libx265) codec. I did not change anything so far as CBR or keyframe settings (2500/250 respectively).

The first try with the ti gave me a slightly larger file, maybe 5 MB or so.

Here's a log file from a 24 minute recording I just made using the hevc_nvenc(libx265) codec (it is towards the end, I had tried to use another codec before that & got an error message- that was the 40.8% dropped frame in the log):
https://obsproject.com/logs/v8bG0POdM2Fj4QGf

The file size from OBS was 487 MB. The last one I did with the H264 was 489 MB, but I think the show was a little longer- I cut this one off at 24:15. After MCEB processed it, the size was 388 MB, so it's far larger than what I had been getting. I also ran the 487 MB file thru Handbrake using the NVENC H265 codec on the fast 1080P30 setting, and it got a lot larger- 569 MB.

So far the big difference in using the ti is MCEB spends a lot less time transcoding. I think using the old card it was around 44 minutes to do a show, it's like 9 now with far less CPU use. If I can't get significantly smaller file sizes I don't see the need for the expensive GPU. I can return it free within 30 days, so I'll need to get this figured out by then.

Thanks for any help or advice.
 
Narcogen

Narcogen

Active Member
Right. I mean, if you want the same quality, but a smaller file, you have to use a quality based rate control setting, not a bitrate one-- because that will give a better looking file at the same (roughly) size.

Or I suppose you could just choose a lower bitrate to get a smaller file size, and then just judge whether the quality is good enough. Either way.
 
N

NS_0607

New Member
Thanks for the replies. I toyed around with various settings recording some 5 minute files and the short answer is the situation was made worse by using the ti. All of my MCEB processed files were also far larger than before regardless of using H264 or H265. I'm going to return it. While I'm sure it's a great gaming/streaming card, it didn't help me and I can use the $ for other things. It will make someone a great open box deal. :)

I can't use CQP with H265, CQP is only available under the "standard" setting.

Using H265, I set the BR down to 2000 then later 1500 (from 2500) and the picture quality was not good enough each time. I saw a decent file and quality compromise using a VBR of 1500-2500, but that limits me to standard settings and H264.
 
koala

koala

Active Member
Of course you can use constant quality mode with nvenc_hevc. See these custom output mode settings:
1561059147764.png


The quality parameter value is the qp=26. As with h.264, lower values mean higher quality and bigger file sizes. You will have to experiment with this parameter, because 26 with hevc is not the same quality as cqp=26 with h.264.

The issue with this output mode is that it isn't using the new nvenc encoder mode that completely handles compositing and encoding in GPU memory, thus relieving the pci-express bus and CPU memory from much load. If you simply want smaller files, I recommend using whatever comes out of the nvenc (new) encoder and recode it with x.264 (handbrake or other tool) with some encoder of your liking. This way you are also able to cut stuff you don't need in the raw footage.
 
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