Add apng2webp

README.md

@@ -4,3 +4,4 @@
 |       yt2mpd.sh | Adds an Youtube video to MPD, with correct title and duration.               |
 | fetch_gaidao.sh | Auf neue Ausgaben von der Gai Dao prüfen, herunterladen.                     |
 |         srtadrm | Remove ads from SRT files with a list of POSIX extended regular expressions. |
+|    apng2webp.sh | Convert animated PNG to animated WebP                                        |

apng2webp.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+# Convert animated PNG to animated WebP. Maximum compression no blend.
+
+set -euo pipefail
+
+if [[ $# -lt 2 ]]; then
+    echo "Usage: ${0} input.png output.webp" >&2
+    exit 1
+fi
+input="$(realpath "${1}")"
+output="$(realpath "${2}")"
+
+mkdir -p apng2webp_work
+pushd apng2webp_work
+
+mkdir -p apngdis
+pushd apngdis
+cp "${input}" "input.png"
+apngdis "input.png"
+popd
+
+counter=1
+for file in apngdis/apngframe*.png; do
+    # shellcheck disable=2086
+    cwebp -lossless -q 100 "${file}" -o "$(printf "%02d" ${counter}).webp"
+    counter=$((counter+1))
+done
+
+webpmux_options=""
+counter=1
+for file in apngdis/apngframe*.txt; do
+    delay=$(grep -Po '=\d+/' "${file}")
+    delay="${delay:1:-1}"
+    webpmux_options="${webpmux_options} -frame $(printf "%02d" ${counter}).webp +${delay}+0+0+0-b"
+    counter=$((counter+1))
+done
+
+# shellcheck disable=2086
+webpmux ${webpmux_options} -o "${output}"
+
+popd
+rm -r apng2webp_work