NVENC AV1 produces larger filesize

1. offizieller Beitrag

    Hi All,

    I just tried using the latest Voukoder Beta supporting the NVENC AV1 encoder. I have a RTX 4090 so it should be possible to use it. I used the Adobe Connector to use it in Media Encoder.

    My main idea using AV1 is for YouTube. I am doing recordings of Gameplay and they end up in a huge filesize and uploading takes a long due to only 50Mbit upload.

    I have a file captured via my Elgato 4k 60 Pro with the following details:

    Resolution: 4k (3840x2160)

    Data Rate: 69392 kbps

    Total bitrate: 69709 kbps

    Frame rate: 59.94 fps

    Codec: I think this Elgato 4k Capture Utility records in H265 HEVC (its HDR gameplay)

    Audio rate: 317 kbps

    Channels: 2 (stereo)

    Sample rate: 48.000 kHz

    Filezise:: 13.8 GB

    Now in Media Encoder I select Voukoder and and set the Preset to Slowest (Best Quality) and the Quantizer at 23 (default). Everything else is at default.

    The resulting quality is fine but the filezise is now 14.3 GB large.

    My I misunderstood the purpose of AV1 but I thought its so great it should reduce the size and be better than HEVC or H264 ? Am I doing something wrong ?

    Thanks a lot!

  • Vouk 26. Oktober 2022 um 18:17

    Hat das Thema freigeschaltet.

    Constant quantizer is the issue here. Because video encoders decides what quantizer to use for which video frame, and using pixel block-based referencing to drop quality on pixel blocks that has a reference from a full quality source frame, and that's why newer video encoders are using constant rate factor (CRF) mode for a variable quality resulting better compression in the same file size. Choosing constant QP disables this feature.