Add jinja templating to script writer

src/templates/ffmpeg_command.sh.j2

@@ -0,0 +1,65 @@
+#!/bin/bash
+set -euo pipefail
+
+# This script is a template. It needs to be rendered with:
+# - video_file: A VideoFile object from models.streams.
+# - output_file: The absolute path to the output file.
+
+# By default, set log level to error.
+LOG_FLAGS=("-loglevel" "error")
+
+# If -v or --verbose is passed as the first argument, remove the log flags
+# to use ffmpeg's default log level (usually 'info').
+if [[ "$1" == "-v" || "$1" == "--verbose" ]]; then
+  LOG_FLAGS=()
+fi
+
+ffmpeg -hide_banner "${LOG_FLAGS[@]}" -i '{{ video_file.video_path.absolute() }}' \
+    -map_metadata -1 \
+{%- if video_file.title %}
+    -metadata title='{{ video_file.title }}' \
+{%- endif %}
+{%- if video_file.date_released %}
+    -metadata date_released='{{ video_file.date_released.strftime("%Y-%m-%d") }}' \
+{%- endif %}
+{%- if video_file.imdb %}
+    -metadata imdb='{{ video_file.imdb }}' \
+{%- endif %}
+{%- if video_file.original_media_type %}
+    -metadata original_media_type='{{ video_file.original_media_type.value }}' \
+{%- endif %}
+    -pix_fmt yuv420p10le \
+{%- for stream in video_file.video_streams %}
+    -map 0:{{ stream.index }} \
+    -c:v libsvtav1 \
+    -crf {{ stream.crf }} \
+    -preset {{ stream.preset }} \
+    -svtav1-params tune=0:film-grain={{ stream.film_grain }}:scd=1 \
+    -vf 'bwdif=mode=0,scale=iw*sar:ih,setsar=1,scale=-2:ih:lanczos' \
+    -g {{ (stream.fps | round * 5) | int }} \
+{%- endfor %}
+{%- for stream in video_file.audio_streams %}
+    -map 0:{{ stream.index }} -c:a:{{ loop.index0 }} libopus \
+    {%- if 'side' in stream.channel_layout %}
+    -filter:a:{{ loop.index0 }} 'channelmap=channel_layout=5.1' \
+    {%- endif %}
+    {%- if stream.tags and stream.tags.language %}
+    -metadata:s:a:{{ loop.index0 }} language={{ stream.tags.language }} \
+    {%- endif %}
+    {%- if stream.tags and stream.tags.title %}
+    -metadata:s:a:{{ loop.index0 }} title='{{ stream.tags.title }}' \
+    {%- endif %}
+    {%- if stream.disposition.default %}
+    -disposition:a:{{ loop.index0 }} default \
+    {%- endif %}
+{%- endfor %}
+{%- if video_file.allow_subtitle %}
+{%- for stream in video_file.subtitle_streams %}
+    -map 0:{{ stream.index }} -c:s:{{ loop.index0 }} copy \
+    {%- if stream.tags and stream.tags.language %}
+    -metadata:s:s:{{ loop.index0 }} language={{ stream.tags.language }} \
+    {%- endif %}
+{%- endfor %}
+{%- endif %}
+    '{{ output_file }}'
+