Max Encode Bitrate through AMF only 100Mbps?

Discussion in 'Videocards - AMD Radeon Drivers Section' started by Espionage724, Oct 6, 2022.

  1. Espionage724

    Espionage724 Master Guru

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    Edit: Oculus goes beyond 100 Mbps with both HEVC and AVC on a 6600 XT. This seems to be a recent improvement.

    Old post:

    With a RX 6600 XT and Quest 2 PCVR, the image is notably blocky, muddy, and the bitrate caps at 100Mbps.

    According to OBS, 100Mbps is a limit of AMF: https://github.com/obsproject/obs-studio/issues/7423

    And on page 11/18 of AMD's AMF documentation, it specifies TARGET_BITRATE and PEAK_BITRATE at 1000000 bits (~100Mbps): https://raw.githubusercontent.com/G...s/AMF/master/amf/doc/AMF_Video_Encode_API.pdf

    This doesn't seem right as I can do 400-800Mbps with a RTX 3060 no problem, and 200Mbps at a minimum is tolerable for Quest 2 PCVR. Is it correct that AMD with AMF can only encode up to 100Mbps? Is it possible to get higher than this through any other means or any other AMD GPUs?
     
    Last edited: Oct 11, 2022
  2. Cryio

    Cryio Master Guru

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    800 Mbps encoding? How? ShadowPlay has a 50 Mbps cap for Ampere.
     
  3. Espionage724

    Espionage724 Master Guru

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    Oculus Debug Tool; the bitrate limit from the GUI maxes at 500Mbps, but you can copy/paste anything higher than that there. I believe I was able to go up to 800Mbps before encoder backup started getting too bad.

    I found 150Mbps from Moonlight mostly tolerable but still some blur around red fonts.

    Someone here reported doing 800Mbps with OBS on Pascal: https://github.com/obsproject/obs-studio/issues/7423#issuecomment-1256412408
     
  4. Banana4Nanners

    Banana4Nanners Master Guru

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    Wouldn't matter if you could increase AMDs AMF encode rate, meta has it hard limited to 100mbps on AMD GPUs over air link. Increase it to whatever you like over USB link cable but it's known that 550+ is little to no benefit
     

  5. Espionage724

    Espionage724 Master Guru

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    I don't think Meta are the ones enforcing the limit. The 100 Mbps limit is enforced by AMF for H.264 and I can confirm that it's stuck there for wired Link too (overlay says it sticks at 100 Mbps regardless if it's set higher in Debug Tool). Wired Link only works with H.264 still.

    HEVC in AMF's source doesn't specifically state a 100 Mbps limit for TARGET nor PEAK bitrates (default peak is 80Mbps on table A-3 for HQ but I imagine Oculus is or should be using low-latency), but VCEEnc reports a 100 Mbps limit for HEVC (not sure if it's enforcing it or AMF).

    The way to check for the limit with Oculus is to force HEVC and read the logs for AMF info. If I feel adventurous enough I'll try to get logs from my 6600 XT.
     
    Last edited: Oct 11, 2022
  6. Espionage724

    Espionage724 Master Guru

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    I did fresh testing with V46 PTC and 22.10.1 drivers, and the entire situation with AMD GPUs and Oculus seems to have changed drastically.

    Basically, both wired and Air Link are reported to go beyond 100 Mbps, and HEVC works on wired Link now too sort-of (it activates but is jittery): https://forums.guru3d.com/threads/a...iscussion-notably-for-vr.443275/#post-6059176
     
    z8373767 likes this.

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