Record container and codec as separate media properties

The useful distinctions

• A media container holds media streams and metadata.
• Track codecs describe encoded stream formats.
• A container label alone does not fully identify its track codecs.

Use one row for the package and one for each track

A useful media description begins with the packaging format, then lists the encoded tracks inside it. That structure avoids statements such as MP4 means H.264, which lose information when another codec is carried in the same container family. For an invented clip, record the package as MP4 and the announced video and audio codec strings in separate track columns. Keep resolution, language, and sample rate in their own fields if known.

Do not fill gaps from familiar combinations

Common packaging combinations can be helpful context, but they do not establish what an uninspected file contains. A filename, content-type declaration, and in-file track table are separate pieces of evidence that can disagree. The HTML example advertises a particular combination for a fictional resource; it does not inspect or decode that resource. An actual compatibility claim would also need the relevant profile, level, configuration, and platform behavior. Keeping the ledger explicit makes those missing measurements visible and supports a later comparison without forcing every format question into a generic yes-or-no claim about the container's name. A track ledger can retain unknown as a real state for any property not yet inspected. Filling that state with a likely codec based on MP4 naming would turn a hypothesis into invented metadata.

Worked example · synthetic

The type names an MP4 container and separately announces AVC and AAC codec strings. The relative source is fictional and does not provide a media file to inspect.

Synthetic text example; no network operation has been performed.

<video controls>
  <source src="synthetic.mp4"
          type='video/mp4; codecs="avc1.4d401f,mp4a.40.2"'>
</video>

Check the interpretation

• Record package and tracks separately.
• Compare declarations with actual track metadata when available.
• Do not infer a codec from an extension alone.