Applies to: Protocol and format interpretation for developers inspecting authorized media delivery.
The useful distinctions
- The VP9 sample-entry identifier is vp09.
- The mandatory codec-string fields include profile, level, and bit depth.
- Those numeric fields use two-digit decimal spelling.
Split the identifier before interpreting numbers
The invented string separates the sample-entry name from three numeric fields. The first numeric value is the profile, the next is the level designation, and the third is the bit depth. Reading them as one long number or as a resolution would erase their meaning. Keep the two-digit spellings in an inventory so that another reader can compare the entry directly with the binding document.
Do not infer the optional colour description
The short form deliberately stops after the mandatory fields. It is useful for teaching the parsing order, but it should not be used to assert a detailed colour pipeline for an uninspected file. A real track review would compare the codec declaration, configuration box, and relevant bitstream information before making that description. The declared profile and depth also do not establish a hardware decoding result. Preserve any implementation observation as a separate item with the tested environment. That approach leaves a clean distinction between what a format string means, what the media actually contains, and what a particular decoder can do with it. A comparison row should show profile 00, level 31, and bit depth 08 separately. That keeps an editor from reading the compact string as one version number or dropping meaningful field boundaries.
Worked example · synthetic
This declares VP9 profile 0, level 3.1, and 8-bit depth using the defined two-digit decimal fields. It is a codec declaration, not a measured quality or playback result.
Synthetic text example; no network operation has been performed.
video/mp4; codecs="vp09.00.31.08" Check the interpretation
- Keep decimal field widths.
- Do not treat 31 as a resolution or bitrate.
- Inspect actual configuration before asserting colour details.