- EBU QC Id
- 0015B
- Name
- Black Bars
- Status
- published
- Category
- objective
- Lead editor
- Eric Carson
- Aliases
- pillar box letter box postage stamp floating video blanking
- Tags
- video
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- Description
- Images that to not fill the intended screen (e.g. 4:3 or 16:9). A movie designed for a cinema screen will often have black bars at the top and bottom when shown on a 16:9 television screen or a 4:3 archive programme will have black bars left and right when shown on a 16:9 screen. Other black bars can be caused by picture shifts caused by timing errors.
- Definition
- Used in Checks, the system shall report the presence of black bars in the video essence with size and duration beyond the specified input thresholds. Optionally the system may report time intervals and bar size where thresholds are exceeded.
Used in Reports, the system shall report a sequence of time intervals where black bars appear regardless of their size and duration. - References
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- Examples
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Input: "Bars Type" = both
Input: "Bars Minimum Size Vertical" = 20 (lines)
Input: "Bars Minimum Size Horizontal" = 20 (pixels)
Input: "Bars Frame Minimum Duration" = 25 (video frames)
Output: "Check Result" = false
Output: "Bars Segment" = from 00:00:10;00 to 00:00:12;00
"Bar Size Right" = 25
"Bar Size Left" = 25
Output: "Bars Segment" = from 00:10:00;00 to 00:10:10;00
"Bar Size Right" = 25
"Bar Size Left" = 25Remark: Use as a Check. CheckResult = true means that at least one time interval longer than 25 video frames, contains black bars larger than 20 pixels or higher than 20 lines. In fact, the optional output BlackBarsSegment shows that two of such intervals were found.
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Input: "Bars Type" = Both
Output: "Bars Segment" = from 00:00:00;00 to 00:00:12;00
"Bar Size Right" = 12
"Bar Size Left" = 12
Output: "Bars Segment" = from 00:00:12;01 to 00:50:10;00
"Bar Size Right" = 25
"Bar Size Left" = 25Remark: Used as a Report.
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- Remarks
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The black bars meant here refer to black bars at the edges of the picture, which occur mostly on viewing or converting 4:3 material in 16:9 frames and viewing 16:9 material in 4:3 frames. But they may also constitute blanking errors.
Note: "blanking errors" refer to the situation where blanking/VBI/VITC is "encroaching" into what should be the visible picture area. Therefore, when the vendor has this ability to detect visible blanking, this area may be ignored for the purposes of the black bar test, meaning that the edge of the frame would start immediately on the line after the blanking errors.
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