Two ratios at different stages
Display aspect ratio describes the intended overall shape. Sample aspect ratio describes an individual sample's displayed proportions. FFmpeg's official FAQ separates them.
If samples are not intended to appear square, dividing encoded width by height is not the whole display-shape calculation. A player must interpret the relevant information correctly.
Use a simple conceptual example
An illustrative100-by100 grid with samples displayed twice as wide as tall forms a 2:1 picture. That arithmetic example is not a claim about a supplied programme or broadcasting standard.
It shows why a metadata inspector and a screenshot can report different-looking shapes without either necessarily describing the same stage.
Inspect before stretching
Use authorised media and reliable source diagnostics where available. Keep encoded dimensions, sample aspect and display aspect fields identified. Do not infer the intended shape from a poster.
If faces or circles look stretched, compare the player's normal aspect mode and the television's scaling independently. A global stretch can conceal a metadata issue while damaging other sources.
Keep processing history in scope
FFmpeg documents that crop and scale operations interact with aspect information. A transformed copy can have different metadata from its source.
Do not rewrite the only file during diagnosis. If two players disagree, compare the same unchanged edition and note their versions and display route.
Report the specific disagreement
Give support the reported fields and observed shape, including where a screenshot was taken. A source-inspector field, player surface and television output can answer different questions.
No media was inspected or converted here. The article explains the documented geometry distinction and does not prescribe a universal aspect override or certify an IPTV source.
Preserve an ordinary reference
Keep one known correctly proportioned item available through the same display settings. If it becomes stretched after the attempted fix, restore the original local choice and retain the source-specific scope. A picture filling every screen pixel is not sufficient success when its proportions are wrong. The useful outcome is a consistent description of the intended source geometry and the exact stage where it changes, rather than an unsupported rule based on one filename or resolution label.
Sources and scope
Scope notes distinguish published documentation, supplied information and editorial methods. They do not report a hands-on service test.
- FFmpeg aspect-ratio FAQ — Official current excerpt distinguishes display and sample aspect ratio and the effects of scaling/cropping. No media conversion performed.
- FFmpeg filter reference — Official current excerpts: setdar/setsar and later processing can change aspect metadata; not a user instruction to modify protected media.
