Intel QuickSync H.265 Max Bitrate 39Mbit/s -> falls back to software encoding above this threshold

[embart0r 1]

I'm experiencing an issue with Intel QuickSync hardware-accelerated encoding on both the latest stable (4.9.3.0) and beta (4.10.0.2) versions of Emby Server.

Problem: Hardware encoding via QuickSync only works for bitrates up to 39 Mbit/s.

When the source bitrate exceeds this threshold, Emby falls back to software transcoding (x265), even though the hardware is capable of handling much higher bitrates.

Hardware:

• GPU: Intel Arc A310
• OS: Linux (TrueNAS Scale)

Evidence from Emby's Hardware Encoder Info:

When checking Transcoding Settings → Preferred Hardware Encoders → Info button, I see the following specifications:

HEVC Encoder:

Adapter #0: 'DG2 Arc A310' Id:22182 (Driver: , Vendor: 32902, SDK Version: 1.255)

Max Bitrate: 39 Mbit/s  ← Limited to 39 Mbit/s
Frame Sizes: 32x32...8192x8192
Color Formats: NV12

Profile              Max Level   Max Bitrate   Bit Depths   Resolutions
Main                 Level 5.1   39 Mbit/s     8           4096x2160@60 - 1920x1080@256
Main Still Picture   Level 5.1   39 Mbit/s                 4096x2160@60 - 1920x1080@256

H.264 Encoder (for comparison):

Adapter #0: 'DG2 Arc A310' Id:22182 (Driver: , Vendor: 32902, SDK Version: 1.255)

Max Bitrate: 234 Mbit/s  ← Correctly shows 234 Mbit/s
Frame Sizes: 32x32...4096x4096
Color Formats: NV12

Profile    Max Level   Max Bitrate   Bit Depths   Resolutions
Baseline   Level 5.2   234 Mbit/s    8           4096x2304@56 - 1920x1080@172
Main       Level 5.2   234 Mbit/s    8           4096x2304@56 - 1920x1080@172
High       Level 5.2   234 Mbit/s    8           4096x2304@56 - 1920x1080@172

 

Expected Behavior: The Intel Arc A310 should support HEVC hardware encoding at bitrates well above 39 Mbit/s (similar to the 234 Mbit/s shown for H.264). Other media servers (Jellyfin) successfully use hardware encoding on the same GPU with target bitrates exceeding 50+ Mbit/s.

Question: Is this 39 Mbit/s limitation a bug, or an intentional restriction?

[Luke 42077]

Hi there, please provide the emby server and hardware detection log files:

How to Report a Problem

Thanks !

[embart0r 1]

Hey, sure here are the logfiles. I've stripped out filenames and hostnames etc. and replaced them by "[REDACTED]"

hardware_detection-63905841404.txt embyserver.txt

Edited February 4 by embart0r
missing details

[Cobester 3]

Interesting. I didn't notice that limitation and see the same thing on mine. Currently running 4.9.2.6b using Intel 14th gen cpu

H.265 (HEVC) encoder:

Adapter #0: 'Arrow Lake-P Intel Graphics' Id:32081 (Driver: , Vendor: 32902, SDK Version: 1.255)
Max Bitrate:	39 Mbit/s
Frame Sizes:	32x32...8192x8192
Color Formats:	NV12
Profile	Max Level	Max Bitrate	Bit Depths	Resolutions
Main	Level 5.1	39 Mbit/s	8	4096x2160@60 - 1920x1080@256
Main Still Picture	Level 5.1	39 Mbit/s		4096x2160@60 - 1920x1080@256

 

Edited February 8 by Cobester

[yocker 1247]

I've see a few Linux threads mention this as well for other programs.
Solution was "lowpower=on" for the driver. How you can possibly add that in Emby i don't know.

You can try and install the Emby diagnostic plugin (found in the catalog) and enter this:



See if that helps.
If it does then you can try:



The first one is just to test if it works, it will pretty much break any quality control setting but is best to test with as it's a setting that will force everything to ignore bitrate limis so is good to test with.
The second one should (in my mind) have quality control settings work and work as normal for Emby.

I don't have any Intel graphics at the moment to test with so can't confirm for my self.

[Luke 42077]

@embart0rhas this helped?

[embart0r 1]

@LukeNo it hasn't - same behaviour as before.

Regarding the lowpower=on mode - there is a checkbox probably setting this parameter in advanced settings for h264.

But for h265 hardware encoder I can't even enter the advanced settings, cause the button for it is missing.

In advanced settings for h264:

[Eigeplackter 90]

Afaik the 39 Mbps limit on the old Arc A310 was/is not a hardware defect, but a firmware-enforced specification.

Intel locked the chip to HEVC Level 5.1, and according to the official HEVC standard, that level caps the bitrate at exactly 39.375 Mbps for the Main Profile.

i.e. I use a B860 now

Level 6.1 and 6.2 Support

Battlemage (Xe2) is designed for the 8K era. To handle 8K resolutions at high frame rates, the hardware must support HEVC Levels 6.1 or 6.2.

• Level 5.1 (Arc A310): Max 39 Mbps.

• Level 6.1 (Battlemage B860): Max 240 Mbps (Main Tier) or even 480 Mbps (High Tier).

  By moving up the level specification, the "throttle" is naturally removed.

Unified Media Engine

In the first Arc generation (DG2), Intel tried to artificially segment the market by crippling the cheaper cards (A310/A380).

With Battlemage, the Media Engine is a unified, highly powerful block.

Whether you have a budget B-series or a high-end card, you get the full "unlocked" encoding power.

---

Comparison Table

Feature	DG2 Arc A310 (Old Gen)	Xe2 Battlemage B860 (Your Card)
HEVC Level	Level 5.1 (Fixed)	Level 6.1 / 6.2
Max Bitrate	39 Mbps	240 - 480+ Mbps
Resolution	4K (4096x2160)	8K (8192x4320)
Reason for Limit	Firmware Lock	Unlocked / Next-Gen Specs

 

EDIT: qed

Quote

user@fedora:~$ ffmpeg -vaapi_device /dev/dri/renderD128 -f lavfi -i testsrc2=duration=5:size=3840x2160:rate=60 \
-vf "format=nv12,hwupload" -c:v av1_vaapi -b:v 100M -maxrate 100M -minrate 100M -bufsize 50M test_av1_force.mp4

Had to use AV1 as H.265 isnt fully supported yet. Brings me a 59M file.

Doing the  math: 59MB*8(bits) / 5 (seconds} approx 94.4 Mbit/s

Edited 22 hours ago by Eigeplackter

[embart0r 1]

I'm quite happy for you that you have a working B860 card.
Your post and "Comparison Table" look quite AI generated to me and contain hardly any reliable information.
I have explained my problem clearly - and now I have to prove something for my own card just because you're making claims about it, which you can't even verify since you have a completely different card.
Nothing from a quick search supports your claims:
https://github.com/intel/media-driver#decodingencoding-features
https://github.com/intel/media-driver/blob/master/docs/media_features.md#supported-encoding-input-format-and-max-resolution
https://en.wikipedia.org/wiki/Intel_Quick_Sync_Video

As already mentioned, it works in Jellyfin and the Arc A310 does support HEVC (up to 10 bit) encoding.

QED with ffmpeg (HEVC HW 10-bit Encode):

ffmpeg -vaapi_device /dev/dri/renderD128 \
  -f lavfi -i testsrc2=duration=5:size=3840x2160:rate=60 \
  -vf "format=p010,hwupload" \
  -c:v hevc_vaapi -profile:v main10 \
  -b:v 100M -maxrate 100M -minrate 100M -bufsize 50M \
  test_hevc_10bit_force.mp4

Results in a ~60MB file. That's 60×8÷5 = ~96 Mbit/s.

[Eigeplackter 90]

As I'm not a native speaker I used Gemini to translate my opinion, so your feeling about AI is correct.

I'm sorry that you feel offended by my input.

However, good luck to you.