From 71c712796c39d26d43946594c7825debe9e1c06f Mon Sep 17 00:00:00 2001
From: Neale Pickett <neale@woozle.org>
Date: Tue, 28 Feb 2023 21:46:21 -0700
Subject: [PATCH] Putting this into a repo

---
 LICENSE.md |  21 +++++++++
 README.md  |  10 ++++
 h264       | 132 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 163 insertions(+)
 create mode 100644 LICENSE.md
 create mode 100644 README.md
 create mode 100755 h264

diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
index 0000000..8175599
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023 Neale Pickett
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+The software is provided "as is", without warranty of any kind, express or
+implied, including but not limited to the warranties of merchantability,
+fitness for a particular purpose and noninfringement. In no event shall the
+authors or copyright holders be liable for any claim, damages or other
+liability, whether in an action of contract, tort or otherwise, arising from,
+out of or in connection with the software or the use or other dealings in the
+software.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..ff2b36a
--- /dev/null
+++ b/README.md
@@ -0,0 +1,10 @@
+This is a shell script to transcode stuff to h.264.
+
+It uses the Raspberry Pi's hardware acceleration
+(`h264_v4l2m2m` codec)
+to encode the h.264 files.
+
+I don't know if the ffmpeg code is immature,
+or if I just don't understand ffmpeg,
+but this codec demands some special treatment,
+which this shell script provides.
diff --git a/h264 b/h264
new file mode 100755
index 0000000..5e129e3
--- /dev/null
+++ b/h264
@@ -0,0 +1,132 @@
+#! /bin/sh
+
+set -e
+
+usage () { cat <<EOD 1>&2; }
+Usage: $0 [OPTIONS...] SRC [SRC...]
+
+Re-encodes to h.264.
+Output will be written to \$SRC.h264.mp4
+
+  -width W    Rescale to no wider than W
+  -height H   Rescale to no taller than H
+  -1080p      Rescale to no bigger than 1080p
+  -720p       Rescale to no bigger than 720p
+  -480p       Rescale to no bigger than 480p
+  -swenc      Software encode instead of hardware
+
+In addition to transcoding video,
+this will force any subtitles into mov_text.
+This is due to some odd interaction between
+ffmpeg, h264_v4l2m2m, and mp4.
+EOD
+
+width=iw
+height=ih
+codec=h264_v4l2m2m
+bitrate="-b:v 2048k"
+while true; do
+  case "$1" in
+    -width|--width)
+      width=$1
+      shift
+      ;;
+    -height|--height)
+      height=$1
+      shift
+      ;;
+    -1080p|--1080p)
+      width=1920
+      height=1080
+      bitrate="-b:v 2048k"
+      shift
+      ;;
+    -720p|--720p)
+      width=1280
+      height=720
+      bitrate="-b:v 3000k"
+      shift
+      ;;
+    -480p|--480p)
+      width=640
+      height=480
+      bitrate="-b:v 512k"
+      shift
+      ;;
+    -swenc|--swenc)
+      codec=h264
+      shift
+      ;;
+    -*)
+      usage
+      exit
+      ;;
+    *)
+      break
+      ;;
+  esac
+done
+
+if [ "$codec" = "h264" ]; then
+  bitrate="-crf 28"
+fi
+
+log () {
+  echo "=== $*"
+}
+
+cmd () {
+  nice "$@"
+}
+
+# This got a height of 719 (n%2 must = 0)
+#-vf "scale='min($width,iw)':'min($height,ih)':force_original_aspect_ratio=decrease,format=yuv420p" \
+
+for fn in "$@"; do
+  base=${fn%.*}
+  filename=$(basename "$fn")
+  intermediate="$base.nut"
+  out="$base.h264.mkv"
+  [ -f "$out" ] && continue
+  case "$fn" in *.h264.mp4) continue ;; esac
+
+  # ffmpeg has some bizarro thing where the h264_v4l2m2m codec won't write to a mkv file,
+  # In addition, some subtitles interfere with it too.
+  # Solution: transcode video + audio into an intermediate file,
+  # then add back any subtitles.
+
+  log "$filename - Scale/Transcode"
+  cmd ffmpeg \
+    -hide_banner \
+    -loglevel warning \
+    -stats \
+    -i "$fn" \
+    -map 0:v \
+    -vf "scale=-2:'min($height,ih)':force_original_aspect_ratio=decrease,format=yuv420p" \
+    -c:v $codec \
+    $bitrate \
+    -map 0:a \
+    -c:a copy \
+    -num_capture_buffers 16 \
+    -num_output_buffers 32 \
+    -y \
+    "$intermediate"
+
+  log "$filename - Add subtitles"
+  cmd ffmpeg \
+    -hide_banner \
+    -loglevel warning \
+    -stats \
+    -i "$intermediate" \
+    -i "$fn" \
+    -map 0:v \
+    -c:v copy \
+    -map 0:a \
+    -c:a copy \
+    -map 1:s? \
+    -c:s copy \
+    -y \
+    "$out"
+
+  echo rm "$intermediate"
+done