Stereoscopic Interleaved file

Type of format	Data format
First released	2010
Developer	Blu-ray Disc Association
Filename extension	xxxxx.ssif
Open Format?	?
Free Format?	?
Magic Number	C1,D1,D2

An SSIF file is a Stereoscopic Interleaved file that contains Dependent-view M2TS files and SEI data.

This file is used only for 3D video played back.

SSIF files are big and uses some type of special compression to fit inside the 50GB disc without loosing video quality. For example, Avatar 3D (2012 Edition, that plays on both 2D and 3D players) has 46 GB of Base-view video files under Drive:\BDMV\STREAM  and 45 GB of Dependent view files under Drive:\BDMV\STREAM\SSIF, but it's all in one 50 GB disc.
 

The 5-digit number “zzzzz” is the same as the number used for the AV stream file “zzzzz.m2ts” that includes the MVC Base view video stream. 

SSIF files have a few magic numbers,C1,D1,D2, it is unknown of the purpose of each one.

Sources

• Blu-ray Official White Paper Tech Specs and 3D specs (PDF) Version 2.5 - 2011

Author(s) : Æ Firestone