The Auto demuxer mode routed only media3's weak container families
(AVI, ASF/WMV, MPEG-PS, Matroska/WebM) through FFmpeg and kept MP4/TS
on media3's extractors, with a second any-container FFmpeg instance
behind media3's list. With the goal of fully switching to the ffmpeg
demuxer, the split served no purpose and the catch-all could never add
coverage once the primary accepts everything.
Collapse the preference to two modes: FFmpeg (default), which demuxes
every progressive container ahead of media3's list, and media3 only as
the user-facing escape hatch in case a file misbehaves. media3's
extractors stay behind FFmpeg, so anything FFmpeg cannot sniff still
reaches them. The catch-all role and the Auto container list are
removed; unknown persisted wire values (including the retired "auto")
resolve to FFmpeg.
Verified on a Pixel 7: MP4, TS, and MKV all demux through FFmpeg under
the default ("sniff accepted mov,mp4 / mpegts / matroska,webm") with
forward and backward seeks landing; JVM suites and analyzer pass.