The FFprobe codec vocabulary is written out in at least four places and none of them
had a test. Two had already drifted apart. `x264`, `hev1`, `x265` and `vp09` resolved
in `CodecNames.videoFromName` and returned null from
`AndroidDeviceCodecs.mimeForCodecName`, so the app identified the codec for the source
card and for routing and then ran the device capability check blind on the same string;
`mpeg4` ran the other way and rendered as a raw name. Nothing could notice, and the
reason is structural: a `when` cannot be enumerated, so no test can ask one table what
the other one knows.
Both are maps now, for that reason alone, and `CodecVocabularyTest` walks the two key
sets. A name added to -- or removed from -- one side alone fails the build. The one
legitimate asymmetry is listed rather than implied: `mpeg4` is decodable input with no
`VideoCodec` to name it, so `CodecNames` is right not to carry it. That list is itself
checked, because otherwise it is an escape hatch -- any future divergence could be waved
through by adding the name to it, and adding `x265` to it now fails.
THIS CHANGES BEHAVIOUR for `x264`, `hev1`, `x265` and `vp09`. A null from
`mimeForCodecName` means "unknown to us: assume the platform can handle it and let a
failed export trigger the FFmpeg fallback", which is the right policy for a name nobody
recognises and the wrong one for a name recognised one file over. A device without the
matching decoder now sends those four to FFmpeg up front instead of spending a doomed
hardware attempt to discover it. No input loses hardware it could have used: each alias
resolves to the MIME its canonical spelling already resolved to, so a device that has
the decoder still answers true. `ConversionRouterTest` still passes and that is not
evidence either way -- every `canDecode` in it is a hand-written stub that never reaches
this table.
#74 is the same family one level down. `describeVideo` answered "Unrecognised" for
`InputProbe.UNPARSEABLE` and `describeAudio` had no such arm, so an unparseable audio
codec would have fallen through to `?: name` -- and the sentinel opens with a NUL, so
the source-info card would have rendered a `Text` beginning with U+0000. The two now
share one body, which is what stops the next arm being added to one side only.
Two corrections to that ticket, taken from the file rather than from the ticket, since
it warns about exactly this:
- It quotes `audioFromName` as opening with `null, InputProbe.UNPARSEABLE -> null`.
It did not; it opened with `null -> null` and the sentinel reached `else`. Naming
the sentinel in the shared lookup therefore changes no answer and is documentation,
not the fix.
- It says `describeVideo`'s arm has no test of its own. It did -- `descriptions stay
readable for unknown and missing codecs` asserts it -- so deleting the shared arm
now reddens three tests across both sides, not one.
Mutations run, each on the full 386-test suite:
add "avc3" to CodecNames only -> CodecVocabularyTest red on two counts,
CodecNamesTest green: 8 tests, 0 failures, which
is the ticket's point about per-table arm tests
delete the UNPARSEABLE arm -> CodecNamesTest red on three, one of them quoting
the NUL back
add "x265" to DECODE_ONLY_NAMES -> CodecVocabularyTest red on the escape hatch
delete "vp09" from the MIME map -> CodecVocabularyTest red on three, which is the
state this commit is fixing
Audio is not cross-checked, and that is a gap rather than a decision: the device
capability check is video-only, so this module has no second audio table to compare
`AUDIO_ALIASES` against. `Media3Engine.audioMimeTypeFor` is the other half and belongs
to #85. `MediaProbe.shortName` (#84) is the fourth table and is untouched here for the
same reason.
Closes#87.
Closes#74.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
JMR-dev
