Protocol conformance

The service’s HLS and DASH output is checked by an automated black-box suite, and the remaining vendor and browser checks are listed with how to run them.

The automated suite

tests/conformance.rs starts the real binary against every fixture below and audits what a player would fetch. Run it with make conformance (it also runs under make test and in CI).

Fixtures: the main H.264/AAC file, the same with moov after mdat, video only, 44.1 kHz stereo audio, and variable frame timing; FFmpeg’s default edit lists and a delayed audio track; two audio tracks; non-square pixels with tagged colour; a QuickTime file; HEVC, VP9, AV1; AC-3, E-AC-3, Opus, and FLAC audio; and audio-only files with one and two tracks. Every reassembled track is decoded by FFmpeg without errors and its packet count compared with the source.

HLS (RFC 8216)

• Playlist starts with #EXTM3U; the protocol version is at least 6, which fMP4 with EXT-X-MAP requires.
• The variant has BANDWIDTH not below AVERAGE-BANDWIDTH, a codec string, and a resolution.
• An AUDIO group reference on the variant matches exactly one EXT-X-MEDIA rendition, and a rendition without a reference is rejected.
• Media playlists are VOD, INDEPENDENT-SEGMENTS, end with ENDLIST, and have an EXT-X-MAP.
• Every EXTINF rounded to whole seconds does not exceed EXT-X-TARGETDURATION.
• Every URI in every playlist resolves and returns 200.

DASH (ISO/IEC 23009-1)

• The manifest has the MPD namespace, type="static", a DASH profile, and valid mediaPresentationDuration and minBufferTime.
• Each Representation has bandwidth and codecs and a SegmentTemplate with a SegmentTimeline.
• $RepresentationID$ and $Number$ substitutions resolve to real objects.
• The timeline does not exceed the presentation duration, and the longest track equals it.

Media bytes (ISO BMFF, CMAF-style layout)

• Init segments have ftyp, moov, exactly one trak, mvex/trex, and empty sample tables.
• Media segments are [styp] moof mdat, every box size tiles its parent exactly, and tfhd uses default-base-is-moof.
• The trun data offset lands exactly on the first payload byte, and the sample sizes sum to the mdat payload.
• mfhd sequence numbers run 1, 2, 3 …; tfdt values are contiguous, each starting where the previous segment ended.
• Video segments begin with a sync sample.
• The duration declared in the playlist or timeline matches the sum of sample durations in the fragment, within one millisecond of rounding.
• HLS and DASH serve byte-identical init and media segments for every track.

Transport

Byte ranges (bytes=a-b, suffix bytes=-n), Accept-Ranges, ETag, If-None-Match, stale If-Range, and immutable caching on media objects.

Decoding

When FFprobe and FFmpeg are installed, each track is reassembled (init plus segments), decoded with ffmpeg -v error with no errors, and its packet count is compared with the source file’s.

The suite was mutation-checked: making the fragment sequence numbers start at 2 fails it immediately.

What is not covered

The suite verifies structural rules the code can be held to. It is not a certification.

Until the vendor validators and browser tests are run and their output recorded here, treat the output as structurally sound and cross-checked but not certified.