Module video 

CA_VP8 are a custom version of a VP8 video by CA. These files contain only video data, no audio.

Within this module are functions to convert these files into IVF files, readable by tools such FFMpeg, VLC or MPV.

These files can usually be found under the movies folder, with the extension .ca_vp8. This format is versioned through a version number in the file’s header. This lib supports has support for reading and writing the versions 0 and 1.

CA_VP8 Structure

Header

V1

Bytes	Type	Data
4	StringU8	Signature of the file.
4	u32	Version of the file.
4	u32	Length of the header.
4	StringU8	FourCC of the video.
2	u16	Width of the video.
2	u16	Heigth of the video.
4	f32	Milliseconds per frame.
4	u32	Unknown.
4	u32	Number of frames - 1.
4	u32	Offset of the frame table.
4	u32	Number of frames.
4	u32	Largest frame.
1	u8	Unknown value.

V0

Bytes	Type	Data
4	StringU8	Signature of the file.
4	u32	Version of the file.
4	u32	Length of the header - 8.
4	StringU8	FourCC of the video.
2	u16	Width of the video.
2	u16	Heigth of the video.
4	f32	Milliseconds per frame.
4	u32	Unknown.
4	u32	Number of frames.
4	u32	Offset of the frame table.
4	u32	Number of frames.
4	u32	Largest frame.

Frames Data

This is valid for versions 0 and 1.

Bytes	Type	Data
Frame table’s offset - header length	&[u8]	Frames data, concatenated.
Until the end of the file	&[Frame Table Entry]	List of entries with each frame metadata (position, size,…).

Frame Table Entry

This is valid for versions 0 and 1.

Bytes	Type	Data
4	u32	Offset of the frame from the start of the file.
4	u32	Size in bytes of the frame’s data.
4	u32	Optional. Unknown value. Only present sometimes.
1	bool	Is the frame a key frame?

Credits for this module:

• Research and initial implementation for this was done by John Sirett here:
  • https://gitlab.com/johnsirett/ca_vp8-reverse

As such, the read/save functions for CaVp8 and Ivf in the submodules of this module (and only those functions) are an exception to the MIT license above and are under the CC-SA 4.0 license, available here:

• https://creativecommons.org/licenses/by-sa/4.0/

Structs

Frame

This struct contains the information needed to locate an specific frame from a video within the raw frame data.

Video

This represents an entire CaVp8 File decoded in memory.

Enums

SupportedFormats

This enum contains the list of formats this lib supports.

Constants

EXTENSION

Extensions used by CaVp8 Files.