Correctly transcode in-device Android screen recordings (which were created by ffmpeg), so that they can be correctly edited and processed further during post. In particular, enforces a fixed framerate and the correct color coefficients.

transcode-raw-screenrecording.sh

#!/bin/bash
# Correctly transcode in-device screen recordings from Android, so they
# do not cause all kinds of mishaps later down the editing and rendering
# pipeline. In particular, enforces a fixed framerate to avoid problems
# with widely varying dynamic frame rates, which can go from anywhere
# a frame every 10s of seconds to 100fps or so. Additionally, we
# enforce the correct color coefficients for the transcoding to avoid
# video tools to guesstimate completely nonsense transformation -- ffmpeg,
# I'm looking at you here.
shopt -s extglob
shopt -s globstar

# Project frame rate; we ensure during transcoding that we get a fixed
# framerate instead of a potentially wildly varying one which can cause
# lots of editing (cut position) problems later in post.
projectfps=25

# Run on all .raw.mp4 video files in all subdirectories. The transcoded
# file will be of the same name, but with only the .mp4 extension, instead
# of .raw.mp4.
for rawvid in **/*.raw.mp4; do
    if [[ "$rawvid" =~ (.*)\.raw\.([^.]+) ]]; then
        vbasename=${BASH_REMATCH[1]}
        vext=${BASH_REMATCH[2]}
        vidfile="$vbasename.$vext"
        echo "raw footage" "$rawvid"
        if [[ -f "$rawvid" ]]; then
            # Raise the loglevel, to avoid the ttyp noise ffmpeg is so
            # proud of. Other than that...
            # - enforce a fixed frame rate
            # - make sure to use the correct color coefficients for
            #   screencast recordings taken directly in-device from Android.
            # - ensure that the transcoded video has the correct color
            #   coefficients explicitly burned in to avoid misinterpretations
            #   (except for totally brain-damaged video tools ignoring this).
            ffmpeg -loglevel warning -y \
                -i "$rawvid" \
                -r $projectfps \
                -crf 18 \
                -color_primaries bt470bg \
                -color_trc gamma28 \
                -colorspace bt470bg \
                "$vidfile"
            if [[ $? -ne 0 ]]; then
                tput setaf 1; echo "transcoding failed, exiting."; tput sgr0
                exit 1
            fi
            tput setaf 2; echo "==> '$vidfile'"; tput sgr0
        else
            tput setaf 5; echo "Skipping non-existing '$rawvid'"; tput sgr0
        fi
    fi
done