[HELP] AV1 NVENC B-Frames

[tomek398]

I want to archive my video files from GoPro camera using AV1 format. 
I have Geforce 5060ti and want to use NVENC as I heard that version supports B-Frames in AV1. I did a few tests with most recent version of Hybrid, however I didn't see any B-frames in encoded AV1 files (using NVECN)

Is there any option I need to activate to add B-frames?

Thanks

[Selur]

As far as I can tell Hybrid is telling NVEncC to use '--bframes 3' by default. (assuming 'NVEncC --check-features' reported that you gpu supports using b-frames)
Looking at the output of the encoder in my quick test:

NVEncC (x64) 8.09 (r3369) by rigaya, Jul 16 2025 12:08:21 (VC 1944/Win)
OS Version     Windows 11 x64 (26100) [UTF-8]
CPU            AMD Ryzen 9 7950X 16-Core Processor [5.52GHz] (16C/32T)
GPU            #0: NVIDIA GeForce RTX 4080 (9728 cores, 2505 MHz)[PCIe4x16][577.00]
NVENC / CUDA   NVENC API 13.0, CUDA 12.9, schedule mode: sync
Input Buffers  CUDA, 44 frames
Input Info     y4m(yv12(10bit))->p010 [AVX2], 640x352, 25/1 fps
Vpp Filters    copyDtoD
Output Info    AV1 main 10bit @ Level auto
               640x352p 1:1 25.000fps (25/1fps)
Encoder Preset quality
Rate Control   VBR
Multipass      none
Bitrate        1500 kbps (Max: 240000 kbps)
Target Quality auto
QP range       I:0-255  P:0-255  B:0-255
QP Offset      cb:0  cr:0
VBV buf size   auto
Split Enc Mode auto
Lookahead      on, 32 frames, Adaptive I Insert
GOP length     250 frames
B frames       3 frames [ref mode: middle]
Ref frames     6 frames, MultiRef L0:auto L1:auto
AQ             on (spatial, temporal, strength 5)
Part size      max auto / min auto
Tile num       columns auto / rows auto
TemporalLayers max 0
Refs           forward auto, backward auto
VUI            matrix:smpte170m,rangedav1d :limited
Others         mv:Q-pel

the encoder git get the information.

From what I remember AV1 does not have b-frames to begin with and the 'b-frame' option in some encoders just referes to a specific combination of interframes referencing each other.

AV1 does have bi-directional predicted frames, but it is not like the way as H.264/HEVC. Instead it has so-called "mini-GOP", which includes series of inter frames that reference each other.

Because of this difference, it is not counted as B frames in the log.

=> https://github.com/rigaya/NVEnc/issues/438

Cu Selur

Cu Selur

[tomek398]

Thanks for a reply. 

I'm not expert on that topic. I just read that B-frames are supported for NVENC AV1 on 5000 series card and did a test. I didn't see any B frames in the output but maybe that is OK. I don't know....
When I look at the output of NVENC H.265 I can simply see B-frames.... 

I'm using Shutter Encoder option to "see" GOP

[Selur]

H.265 and AV-1 are totally different formats,..
(shutter encoder is based on ffmpeg)

[tomek398]

H.265 and AV-1 are totally different formats,..

I know, but even NVIDIA is showing "B-Frames" in the settings of OBS for NVENC AV1 (bottom of the image)
NVIDIA NVENC Obs Guide | GeForce News | NVIDIA

It is all quite confusing....
I just want to be sure that I'm using best available settings for my hardware. 
Thanks 

H.265 and AV-1 are totally different formats,..
(shutter encoder is based on ffmpeg)

---

NVIDIA says about "...ultra-high quality (UHQ) mode to AV1..." but TBH I don't know what it means.....

Video Codec SDK | NVIDIA Developer

NVIDIA GPUs contain an on-chip hardware-accelerated video encoder (NVENC), which provides video encoding for H.264, HEVC (H.265) and AV1 codecs.

The software enhancements in SDK v13.0 enable extending ultra-high quality (UHQ) mode to AV1 encoding.. This makes AV1 encoding on Blackwell NVENC comparable to software AV1 encoding with ~3X throughput. The UHQ HEVC mode was introduced in the SDK v12.2 in the Ada generation.

[Selur]

Can't really say what settings to use another tool, which might use different language.
Nor sure whether cqp should is constant or constrained and if q stands for quality or quantizer.

NVEncC uses a different naming, see: https://github.com/rigaya/NVEnc/blob/mas...de-options

[tomek398]

Professional-Grade Video for All
GeForce RTX 50 Series GPUs deliver a generational leap in NVIDIA encoders and decoders with support for the 4:2:2 pro-grade color format, multiview-HEVC (MV-HEVC) for 3D and virtual reality (VR) video, and the new AV1 Ultra High Quality mode.

GeForce RTX 50 Series GPUs Double Creative Performance | NVIDIA Blog

What is that " AV1 Ultra High Quality mode" and can I activate it in Hybrid?

[Selur]

No clue what it actually does.
Since NVEncC doesn't mention it, Hybrid doesn't support it.
=> if you want it, you probably best should post a feature request over at https://github.com/rigaya/NVEnc/issues
If rigaya adds it to NVEncC I'll add support for it in Hybrid.

Cu Selur

Ps.: I added a question regarding UHQ to https://github.com/rigaya/NVEnc/issues/709

[Selur]

UHQ is the same as using:

-b 7 --tf-level 4 --lookahead 32 --lookahead-level 3 --no-i-adapt --no-b-adapt --bref-mode middle

see: https://github.com/rigaya/NVEnc/issues/6...2746007405

Cu Selur