The previous attempt set ``demuxer_lavf_o`` as an init kwarg with a
comma-laden ``protocol_whitelist=file,http,https,tls,tcp`` value.
mpv rejected it with -7 OPT_FORMAT because python-mpv's init path
goes through ``mpv_set_option_string``, which routes through mpv's
keyvalue list parser — that parser splits on ``,`` to find entries,
shredding the protocol list into orphan tokens. Backslash-escaping
``\,`` did not unescape on this code path either.
Splits the option set into two helpers:
- ``build_mpv_kwargs`` — init kwargs only (ytdl=no, load_scripts=no,
POSIX input_conf null, all the existing playback/audio/network
tuning). The lavf option is intentionally absent.
- ``lavf_options`` — a dict applied post-construction via the
python-mpv property API, which uses the node API and accepts
dict values for keyvalue-list options without splitting on
commas inside the value.
Tests cover both paths: that ``demuxer_lavf_o`` is NOT in the init
kwargs (regression guard), and that ``lavf_options`` returns the
expected protocol set.
Audit-Ref: SECURITY_AUDIT.md finding #2
Severity: High