every.channel: sanitized baseline

scripts/determinism-cmaf.sh

@@ -0,0 +1,108 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "${root}"
+
+input=""
+seconds="6"
+chunk_ms="2000"
+
+usage() {
+  cat >&2 <<'EOF'
+usage:
+  scripts/determinism-cmaf.sh --input <TS_FILE_OR_URL> [--seconds N] [--chunk-ms MS]
+
+what it does:
+  - runs the CMAF (HLS fMP4) encoder/segmenter twice with the deterministic x264 profile
+  - compares sha256 of init + segments to check byte-for-byte determinism
+
+notes:
+  - requires `ffmpeg` on PATH
+EOF
+}
+
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --input)
+      input="${2:-}"
+      shift 2
+      ;;
+    --seconds)
+      seconds="${2:-}"
+      shift 2
+      ;;
+    --chunk-ms)
+      chunk_ms="${2:-}"
+      shift 2
+      ;;
+    -h|--help)
+      usage
+      exit 0
+      ;;
+    *)
+      echo "error: unknown arg: $1" >&2
+      usage
+      exit 2
+      ;;
+  esac
+done
+
+if [[ -z "${input}" ]]; then
+  echo "error: --input is required" >&2
+  usage
+  exit 2
+fi
+
+tmp="$(mktemp -d)"
+trap 'rm -rf "$tmp"' EXIT
+
+ts="$input"
+if [[ "${input}" == http://* || "${input}" == https://* ]]; then
+  ts="$tmp/in.ts"
+  ffmpeg -hide_banner -loglevel error -nostdin -y \
+    -t "${seconds}" -i "${input}" -c copy -f mpegts "${ts}"
+fi
+
+seg_secs="$(python3 - <<PY
+ms=int("${chunk_ms}")
+print(f"{ms/1000:.3f}")
+PY
+)"
+
+run_one() {
+  out="$1"
+  rm -rf "$out"
+  mkdir -p "$out"
+  (cd "$out" && ffmpeg -hide_banner -loglevel error -nostdin -y \
+    -i "pipe:0" \
+    -map 0:v:0 -map 0:a:0? -sn -dn -map_metadata -1 \
+    -c:v libx264 \
+    -c:a aac -b:a 128k -ac 2 -ar 48000 \
+    -pix_fmt yuv420p -g 60 -keyint_min 60 -sc_threshold 0 -bf 0 \
+    -threads 1 \
+    -fflags +bitexact -flags:v +bitexact -flags:a +bitexact \
+    -f hls \
+    -hls_time "${seg_secs}" \
+    -hls_list_size 0 \
+    -hls_segment_type fmp4 \
+    -hls_flags independent_segments \
+    -hls_fmp4_init_filename init.mp4 \
+    -hls_segment_filename segment_%06d.m4s \
+    index.m3u8 < "$ts")
+}
+
+run_one "$tmp/a"
+run_one "$tmp/b"
+
+(cd "$tmp/a" && shasum -a 256 init.mp4 segment_*.m4s | sort) > "$tmp/a.sha"
+(cd "$tmp/b" && shasum -a 256 init.mp4 segment_*.m4s | sort) > "$tmp/b.sha"
+
+if diff -u "$tmp/a.sha" "$tmp/b.sha" >/dev/null; then
+  echo "OK: deterministic (init + segments match)"
+else
+  echo "DIFF: non-deterministic output"
+  diff -u "$tmp/a.sha" "$tmp/b.sha" || true
+  exit 1
+fi
+