convert.sh

#!/usr/bin/env bash
set -euo pipefail

if [ $# -lt 1 ] || [ ! -d "$1" ]; then
  cat >&2 <<'EOF'
Usage: convert.sh <directory-with-mp4s>

Recursively converts dated .mp4 recording segments under <dir> to numbered .mov
for DaVinci Resolve on Linux (video stream-copied, audio re-encoded to 16-bit
PCM 48kHz stereo so Resolve can play the audio).

Each session folder's segments become mov/01.mov .. mov/NN.mov, sorted by
filename date ascending (lowest date = 01). Files without a date in the name
are skipped. Original .mp4 files are left untouched.
EOF
  exit 1
fi

src_dir="$1"
dated_re='.*/[0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}-[0-9]{2}-[0-9]{2}\.mp4'

# Unique folders containing dated mp4 segments, sorted.
mapfile -d '' folders < <(find "$src_dir" -type f -regextype posix-extended -iregex "$dated_re" -printf '%h\0' | sort -zu)

if [ ${#folders[@]} -eq 0 ]; then
  echo "No dated .mp4 segments (YYYY-MM-DD HH-MM-SS.mp4) found under: $src_dir"
  exit 0
fi

converted=0
skipped=0
failed=0

for folder in "${folders[@]}"; do
  # Dated mp4s directly in this folder, sorted (name sort == chronological for OBS).
  mapfile -d '' files < <(find "$folder" -maxdepth 1 -type f -regextype posix-extended -iregex "$dated_re" -print0 | sort -z)

  N=${#files[@]}
  if [ "$N" -eq 0 ]; then
    continue
  fi

  n_str="$N"
  width=${#n_str}
  if [ "$width" -lt 2 ]; then
    width=2
  fi

  if [ "$N" -gt 1 ]; then s="s"; else s=""; fi
  echo "==> $folder  ($N segment$s)"

  i=0
  for f in "${files[@]}"; do
    i=$((i + 1))
    out_name="$(printf "%0${width}d" "$i")"
    out="$folder/mov/$out_name.mov"
    base="$(basename "$f")"

    if [ -f "$out" ]; then
      echo "    [$i/$N] skipped (exists): $out_name.mov  <-  $base"
      skipped=$((skipped + 1))
      continue
    fi

    mkdir -p "$folder/mov"
    echo "    [$i/$N] converting: $base -> $out_name.mov"

    if ffmpeg -y -loglevel error -i "$f" \
          -c:v copy \
          -c:a pcm_s16le -ar 48000 -ac 2 \
          "$out"; then
      converted=$((converted + 1))
    else
      echo "    ! FAILED: $f" >&2
      rm -f "$out"
      failed=$((failed + 1))
    fi
  done
done

echo ""
echo "Done: $converted converted, $skipped skipped, $failed failed."