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                              Daggerfall VID File Format
                                   5 December 2003

This is the format for the .VID files that come with TES:Daggerfall. They contain
short videos used in the game for intros and for the main quest.
					

  OVERALL VID FORMAT
=======================================
The over file is composed of a main header followed blocks of audio and video
data. 

	bytes 1 - 787 :	Header
    bytes 788+	    Audio/Video Blocks
					...

The type of block is identified by the first byte in the block.

	0x01 = Video, Compression #1
	0x03 = Video, Compression #2
	0x04 = Video, Compression #3
	0x14 = End Of File
	0x7D = Audio
	0xA6 = Audio, Start Frame


  HEADER
=======================================
The header is always the first 787 bytes of the VID file.

	Bytes   1 -   3:	ASCII	Always "VID"
	Bytes   4 -   5:	INT16	Always 0x00 02 (512)
	Bytes   6 -   7:	INT16	Number of Frames
	Bytes   8 -   9:	INT16	Video Frame Width (256 or 320)
	Bytes  10 -  11:	INT16	Video Frame Height (200)
	Bytes  12 -  13:	INT16	Unknown
	Bytes  14 -  16:	???		Always 0x0E 00 02
	Bytes  17 - 784:	RGB		256-color VGA palette. Each palette entry is
                                composed of 3 triplets (R/G/B) ranging in 
                                value from 0 to 63.
	Bytes 785 - 787:	???		Always 0x7C 00 00 (might be a special record?)


  AUDIO BLOCK - 0xA6 and 0x7D
=======================================
The audio blocks hold the audio for each frame.

	Bytes  1 - 1: CHAR8  Block Type (0xA6 or 0x7D). Both types appear to have
                         the same format. The 0xA6 block is always the first
						 block in the file after the header.
	Bytes  2 - 3: INT16	 Audio block data length
	Bytes  4 - ?: AUDIO	 Audio data. 8-bit, 11025 Hz audio


  VIDEO BLOCK - 0x01, 0x03 and 0x04
=======================================
The basic structure of the video blocks is all the same:

	Bytes 1 - 1: CHAR8  Block Type (0x01, 0x03 or 0x04).
	Bytes 2 - 3: INT16	Unknown value
	Bytes 4 - ?: VIDEO  Compressed video data.

Each type of video block has a slightly different compression format (see below
for details). Unfortunately there is no record size so you must completely parse
the video data in order to find the next block.

It is important to note exactly how the video frames go together. Only the 0x03
video block actually contains a full frame of data. The 0x01 and 0x04 types only
contain the pixels that have changed from the previous frame. Thus, generally in
order to render any one frame you must also render all previous frames up to the 
first 0x03 video block. The transparent pixel for 0x01 and 0x04 frames is the
pixel 205 (0xCD).

The video frames are played back usually at around 10 frames per second. Use the
audio block length to determine the playing time for a frame (some frames, such as
the first or last, are longer than others).


  VIDEO COMPRESSION - 0x01
=======================================
The video data in a form of RLE compression with the following algorithim used
for uncompression:

	InputByte = Read 1 Byte From File

	if ( InputByte >= 0x80 )
		RunLength = InputByte - 0x80
		Add RunLength Transparent Pixels to Frame

	else if ( InputByte == 0 )
		End of Video Frame

	else 
		RunLength = InputByte
		Read RunLength Bytes From File and Copy to Frame
	endif


  VIDEO COMPRESSION - 0x03
=======================================
This is usually the first video block in the file and contains a full frame of 
video in regular RLE format. The basic uncompressing algorithm is:

	InputByte = Read 1 Byte From File

		/* RLE compression */
	if (InputByte >= 0x80) 
		NumberofBytes = InputByte - 0x80
		InputByte = Read 1 Byte From File
		Add NumberofBytes of InputByte to Video Frame
    else if (InputByte == 0)
		End of Video Frame		
    else 
		NumberofBytes = InputByte
		Read NumberofBytes from File and Copy to Video Frame
	endif


  VIDEO COMPRESSION - 0x04
=======================================
This format has an extra header variable:

	Bytes 4 - 5: INT16  Y-Offset. The video frame data starts at this line in
                        the frame.

What follows is the video frame data in the same format as the 0x01 type.


   CREDITS
=======================================

	Andux (andux@bigfoot.com)
		http://meepo.dnsalias.org/ (slow, frequently offline site)
		http://scrawnykid.virtualave.net/ (fast, slightly broken site)
		ICQ: 24517071

	Dave Humphrey (dave@uesp.net)
		http://www.uesp.net/

	Gavid Clayton (interkarma@yahoo.com.au)