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0001W - Active Format Description
published
0001W v5.0
Item image
ACTIVE FORMAT DESCRIPTION
AFD Value(s)
Aspect Ratio(s)
Expected AFD Value
AFD absence, Value, Mismatch
https://qc.ebu.io/items/0001W/versions/5-0-0/
Check
Report
Summary
EBU QC Id
0001W
Name
Active Format Description
Status
published
Category
absolute
Lead editor
Malateshgouda Karegoudar
Aliases
active format descriptor AFD Pillarbox Letterbox
Tags
video MXF
Versions
Version Status Edition date Saved by Note
Details
Description
The AFD describes the aspect ratio of the active picture and safe cut-out areas. Popular examples are Pillarbox and Letterbox.
Definition
Used in Checks, the system shall read out the Active Format Description (AFD) indicated in the wrapper metadata and check if it matches the expected one specified in the input. Optionally, the system may report the AFD value.

Used in Reports, the system shall read out the Active Format Description indicated in the wrapper metadata and report it.
References
Examples

  • Input: "Active Format Description Expected" = 1010
    Output: "Check Result" = false
    Output: "Active Format Description" = 1001
    Output: "Active Format Description Translated" = "In a 4:3 coded frame: Full frame 4:3 image, the same as the coded frame. In a 16:9 coded frame: Pillarbox 4:3 image, horizontally centered in the coded frame"

    Remark: Used as a Check.

  • Input: none
    Output: "Active Format Description" = 1001
    Output: "Active Format Description Translated" = "In a 4:3 coded frame: Full frame 4:3 image, the same as the coded frame. In a 16:9 coded frame: Pillarbox 4:3 image, horizontally centered in the coded frame"

    Remark: Used as a Report.

Input parameters
Name Default value Description Data model name Unit Locator
Output parameters
Name Alias Description Data model name Unit Locator
Test material
Title Version Download
Remarks
Remarks
This Test is a readout only and includes no measurement.

Some QC tools also use the aspect ratio bit to calculate the AFD value in MXF. This may result in different QC results from the one defined in this Test!

AFD code data bits a3-a0 are defined in SMPTE ST 2016-1 Table 1.
Please note, in MXF the AFD is 8 bits in total (4 Bits for AFD, 1 Bit for Aspect Ratio, 3 Bits to ignore).
For a better bitstream comparison, in this QC Test the relevant bits are a3-a0, the other bits shall be ignored.

Bits a3-a0 are defined in ST 377-1 as the following:

Excerpt from SMPTE ST 377-1:
If the MXF file being read has the Version property of the Preface Set equal to 1.3 or higher:
decoders shall ignore b7;
decoders shall interpret b6-b3 as AFD a3a2a1a0;
decoders shall interpret b2 as Active Ratio;
and decoders shall ignore b1-b0.

If the MXF file being read has the Version property of the Preface Set lower than 1.3 and both b6 and b5 equal 0:
decoders should ignore b7;
decoders should interpret b3-b0 as AFD a3a2a1a0; and
decoders may interpret b4 as Active Ratio.

If the MXF file being read has the Version property of the Preface Set lower than 1.3 and either b6 equals 1 or b5 equals 1:
decoders should ignore b7;
decoders should interpret b6-b3 as AFD a3a2a1a0; and
decoders should interpret b2 as Active Ratio; and
decoders should ignore b1-b0.
User discussions
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