Linux DaVinci Resolve back to original bitrate on h265 using nvidia hwaccel

cuda_gopro_export.sh

#!/usr/bin/bash
#
# Author: BowlineDandy
#
# Convert DaVinci Resolve Videos Back to Original GoPro sizes
# And have them be web friendly as well
# Outperforms Compressor in Mac
# Requires Nvidia GPU
# Requires CUDA Enabled ffmpeg (Custom compiled from Source)
#
# See: https://developer.nvidia.com/blog/nvidia-ffmpeg-transcoding-guide/
#
# cuda_gopro_export example.mov

VERSION=1.0

# Check if input file exists
if [[ ! -f "$1" ]]; then
    echo "Input file not found!"
    exit 1
fi

DEBUG=1
FILENAME=$1
RESIZE=$2
CUSTOM_BITRATE=$3
VERBOSE=info
HWACCEL=cuda
VIDEO_CODEC=hevc_nvenc
if [[ $CUSTOM_BITRATE ]]; then
    VIDEO_BITRATE=$CUSTOM_BITRATE
else
    VIDEO_BITRATE=60M # Same bitrate GoPro 7 4k footages comes at
fi
AUDIO_CODEC=aac
AUDIO_BITRATE=128k

FFMPEG_PARAM=('-vsync' "0")
FFMPEG_PARAM+=('-hwaccel' "$HWACCEL")
FFMPEG_PARAM+=('-hwaccel_output_format' "$HWACCEL")
FFMPEG_PARAM+=('-y')

FFMPEG_PARAM+=('-i' "$FILENAME")
FFMPEG_PARAM+=('-v' "$VERBOSE")
FFMPEG_PARAM+=('-c:v' "$VIDEO_CODEC")

if [[ $RESIZE ]]; then
    if [[ $RESIZE == "1080" ]]; then
        FFMPEG_PARAM+=('-vf' "scale=1920:1080")
    else
        FFMPEG_PARAM+=('-vf' "scale=$RESIZE")
    fi
fi

FFMPEG_PARAM+=('-b:v' "$VIDEO_BITRATE")
FFMPEG_PARAM+=('-movflags' "+faststart") # Web Optimized

NAME=$(basename $FILENAME | sed 's/\(.*\)\..*/\1/')

PASS_1_PARAMS=('-pass' '1')
PASS_1_PARAMS+=('-an')
PASS_1_PARAMS+=('-f' 'null')
PASS_1_PARAMS+=('/dev/null')

PASS_2_PARAMS=('-pass' '2')
PASS_2_PARAMS+=('-c:a' "$AUDIO_CODEC")
PASS_2_PARAMS+=('-b:a' "$AUDIO_BITRATE")

if [[ $RESIZE ]]; then
    PASS_2_PARAMS+=("$NAME-$RESIZE.mp4")
else
    PASS_2_PARAMS+=("$NAME-cuda.mp4")
fi

FN_1_ARGS="${FFMPEG_PARAM[@]} ${PASS_1_PARAMS[@]}"
FN_2_ARGS="${FFMPEG_PARAM[@]} ${PASS_2_PARAMS[@]}"

if [[ $DEBUG -ne 0 ]]; then
    echo "[[ NAME ]] - ${NAME}"
    echo
    echo "[[ FN_1_ARGS ]] ${FN_1_ARGS}"
    echo
    echo "[[ FN_2_ARGS ]] ${FN_2_ARGS}"
fi

ffmpeg $FN_1_ARGS && ffmpeg $FN_2_ARGS

# Check if input file exists
if [[ -f "ffmpeg2pass-0.log" ]]; then
    echo "Cleaning up"
    rm ffmpeg2pass-0.log
fi

Tested on Ubuntu/Pop_OS! 20.04 lts

Better compression/quality than Apple's Compressor with much faster encode times (Using nvidia geforce gtx 1060 ssc)