Free Film Project

Free Film Project - Formats

This will document all the data and file formats for the project. This is intended as a guide for other programmers wishing to contribute to the project.

Data Formats

Video files should have alpha-channel information.

File Formats

Project Managers should be able to read/write GNU makefiles and GNU autoconf files.
Script editors and storyboarding packages should be able to exchange files (although data used will depend on the package type).
Modellers should be able to write Renderman-compliant files - this can be done via external filters, if necessary.
Modellers should be able to write FFP-compliant files. This is the only mandatory internally-supported format.
Rendering packages should be able to read Renderman-compliant files - this can be done via external filters, if necessary.
Rendering packages should be able to read FFP-compliant files. This is the only mandatory internally-supported format.
The output from a video editing package should be usable (losslessly, if possible) as the input to any FFP video editing package, including itself.

In NO case should non-free source files or headers be used. If this would make it impractical to use a listed file format, that format should be excluded. The free nature of the project comes first. We can always write more software.

FFP-compliant files have a corresponding meta-file. This meta-file has the same format for ALL data files and is used to synchronise components.

The FFP meta-file is defined as follows:

Field 0: 32-bit value. ID of component. 0 = Film as a whole.
Field 1: 32-bit value. ID of parent component. 0 = Film as a whole.
Field 2: 8-bit value. Layer in medium. 0 = Uppermost.
Field 3: 32-bit value. Start time. Microseconds from start of parent.
Field 4: 32-bit value. End time. Microseconds from start of parent.
Field 5: 8-bit value. Order of differentiation.
Field 6+n: 32-bit value. Initial value of d(n)x/dy(n)

Field 0 defines the ID of the component. 0 is reserved for the film as a whole.

Field 1 defines the ID of the parent component. All values from here on are defined relative to the parent object. Thus, if a scene contains sound and video, if the scene is moved, both sound and video are moved. This value can not be the same as the value in field 0. (A component cannot be its own parent.) For this reason, the component with an ID of 0 has no defined value for the parent, other than it cannot be 0.

Field 2 defines how identical media types should be layered. The following cases are defined.

In the case of documents (eg: scripts), this value only has meaning for folding editors, in which case it mandates how the levels connect.
In the case of images or video, this value only has meaning for pictures or streams with an alpha channel.
In the case of audio, lower "layers" are more "distant" (ie: fainter). Other effects are undefined by this meta-data.

Field 3 defines where the data fits, relative to the start of the parent component. This ensures that sub-components are attached to the correct point in the sequence, independently of the editing of any other components.

Field 4 defines where the data ends, relative to the start of the film. This must have a value greater than that in field 1. It is stored relative to the parent, rather than relative to the start of the component, to simplify the posititioning of sub-components within a parent component.

Field 5 defines how complex the time sequence is, in terms of the order of differentiation required to define it. eg: O(0) = constant steps, of size defined in field 6. O(1) = ax+b size steps, where a is in field 7 and b is in field 6. etc.

Fields 6 onwards define the constants used to generate the time sequence. This allows for a variable time sequences.

For all data types other than text, if the component's data does NOT exactly match the number of points of time defined in the meta-data, the data is expanded or compressed to fit within the time-slot given in the meta-data. Where the meta-data defines a non-linear sequence, it is up to the implementor as to how to present the sample.

Return to [ Free Film Project's home page | GNU's home page ].

Please send Free Film Project inquiries & questions to jd9812@my-dejanews.com.

Please send FSF & GNU inquiries & questions to gnu@gnu.org. There are also other ways to contact the FSF.

Please send comments on these web pages to webmasters@gnu.org, send other questions to gnu@gnu.org.

Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.

Updated: $Date: 2011/10/24 19:36:51 $ $Author: jturner $