Blu Print OFS File Format



Document # BD-03-008-0010 Date Created 11/20/2009
Title OFS File Format (Offset Metadata Sequence )
Current Version 0.2 Category File Import
Author(s) Tommy Choy
Comments This file format is for data interchange between the offset metadata editing system & Blu-print
Additional Files
Version Date History and Changes
0.1 11/20/2009 First Draft based on BD-ROM_Part3_V2.4D2_091109.pdf
0.2 12/08/2009 Revisions based on BD-ROM_Part3_V2.4D3_091203.pdf


  1. Introduction 3
  2. Format of the OFS File 3


This file format is used for data interchange between the offset metadata editing system and Blu-print.

Offset metadata is required for authoring 3D (stereoscopic) Blu-ray discs when using 1- plane + offset presentation modes in the PG & IG streams. Offset values (pixels) determine the perceived depth of an object when creating the stereoscopic effect. This offset metadata is prepared at the time of asset creation and then imported into the Blu- ray authoring system for further processing.

Each OFS file contains the metadata for one offset sequence. Each file contains continuous frame-by-frame offset metadata (direction & value) in Binary format. The file header contains the signature, version, frame rate, and drop-frame flag in Binary format. The file extension is OFS.

Format of the OFS File


filename.ofs {

signature 8*8 bslbf
version 8*4 bslbf
guid frame_rate 8*16


bslbf uimsbf
drop_frame_flag 4 bslbf
number_of_rolls 8 uimsbf
reserved 8*2 bslbf
for(i=0; i<number_of_rolls; i++){ marker_bits 1*8 bslbf
start_timecode 4*8 bslbf

for(j=0; j<number_of_frames; j++){

32 uimsbf
offset_direction 1 bslbf
offset_value 7 uimsbf




signature : An 8-byte field that identifies this file as an OFS file. This field shall have a value 0x894f46530d0a1a0a.

version : A four-character string that indicates the version of the file format of OFS file. This field shall have a value of “0100” coded according to ISO 646.

guid: A 16-byte field that may be used to reference this offset metadata sequence in the context of many graphics streams in one clip sharing the same offset metadata sequence. This value may also be used to trace this offset metadata sequence in case subsequent processing (e.g. import into authoring system) copies and divides it into many parts. This value is generated upon creation of a new offset metadata sequence.

frame_rate: This 4-bit field specifies the frame-rate of the video stream associated with this offset metadata. Refer to BD-ROM Part 3-1 Section Table 5-24.

drop_frame_flag: The drop_frame_flag can be set to either ‘0’ or ‘1’. It may be set to ‘1’ only if the frame rate is 29.97Hz. If it is ‘0’ then frames are counted assuming rounding to the nearest integral number of frames per second, for example 29.97Hz would be rounded to and counted as 30Hz. If it is ‘1’ then frame numbers 0 and 1 at the start of each minute, except minutes 0, 10, 20, 30, 40, 50 are omitted from the count.

number_of_rolls: This 8-bit field indicates the number of rolls composing the sequence. reserved: reserved shall be set to 0x00.

marker_bits: marker_bits shall be set to ‘00000000’.

start_timecode: A 4-byte field that indicates the timecode (hr., min., sec., frame) of the video frame corresponding to the first offset metadata of a roll of the sequence. Each byte indicates one part of the timecode with most significant first. For example, starting timecode of 01:02:30:04 is set in this field with 0x01021e04.

number_of_frames: This 32-bit field indicates the number of offset metadata (one per video frame).

offset_direction: This flag indicates offset direction. offset_value: This value indicates offset value by pixel.

How to provide the OFS file to the authoring system

The OFS file is usually provided to the authoring system together with a BDN file which contains the reference to it. When the BDN file is imported in the authoring system, the associated OFS files is automatically imported. For details of the BDN file, please refer to the BDN schema (BD-03-006-0100b BDN File Format.xsd).

For example, the following tag in the BDN file references an OFS file named «Example_1POffset_PG.ofs»:

<Stereoscopic PresentationMode=»1POffset» OFSFilename=»Example_1POffset_PG.ofs» OFSGuid=»{3F2504E0-4F89-11D3-9A0C-0305E82C3301}»/>