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Text File | 1995-11-07 | 11.2 KB | 428 lines

************************************************************************ FRANÇAIS -------- DEEP est un format d'image IFF standard (Interchange Format File) au même titre que l'ILBM. Nous vous en rappelons ici la description officielle agrémentée de la description du format d'icône utilisé par TVPaint 3.0 et Broadcast Painter. ENGLISH ------- Here is an offcial description of the DEEP file format, a standard IFF (Interchange Format File) just as the ILBM. See also the description of the saved-in icon used by TVpaint 3.0 and Broadcast Painter. ************************************************************************ CONCEPTS -------- Un fichier IFF commence par les 4 lettres FORM, un MOT LONG (32 bits) qui contient la taille de ce qui suit, 4 lettres d'identification du type de format (ici DEEP), puis une série de chunks. Cette entête permet de reconnaître le format sans tenir compte des extension du nom du fichier. Cette extension (.dip) doit tout de même être sauvegardée dans le monde PC/Windows pour pallier à la gestion anarchique des autres formats... Le format IFF se compose de différents "chunk" qui contiennent chacun des données particulières (palette, icône, informations, son, pixels...). Un chunk commence TOUJOURS par 4 caractères (lettres) d'identifications, suivis d'un MOT LONG (32 bits) qui contient la taille des données sui- vantes, suivi des données elles-mêmes. Le chunk suivant se trouve juste après, ALIGNÉ SUR UN MOT SHORT (16 bits) TOUTES les valeurs sont écrites en BIG INDIAN (valeur la plus significative, octet de poids fort en premier). CONCEPTS -------- An IFF file begins with the 4 letters FORM, a LONG WORD (32 bits) which contains the size of the following then 4 identification letters of the format type (here it is DEEP) and then a series of chunks. This heading enable to identify without taking in account the extension in the file name. Unfortunately this extension (.dip) must be saved in the PC/Windows world because of the lack of intelligent format... The IFF format is composed with different chunks each contain specific datas (color palette, icon, informations, sound, pixels...) A chunk ALWAYS begins with 4 identification characters (letters), then a LONG WORD (32 bits) which contain the size of the following datas, then the datas themselves. The next chunk is placed just after, ALIGNED ON A SHORT WORD (16 bits). EVERY values are written in BIG INDIAN mode (the most significant value first). ************************************************************************ IFF FORM / CHUNK DESCRIPTION Form / Chunk ID : FORM DEEP (Deep pixels) Chunk DGBL (Deep GloBaL information) Chunk DPEL (Deep Pixel ELement) Chunk DLOC (Deep display LOCation) Chunk DBOD (Deep data BODy) Chunk DCHG (Deep CHanGe buffer) ** FORM *************************************************************** FORM ID : DEEP (DEEP pixels) FORM purpose : To allow faster loading and saving of images when pixels are stored in consecutive memory locations and provide support for common extensions implemented on advanced graphics cards. FORM description : This FORM is designed to provide support for a variety of deep pixels, included 24 bits images. A deep pixel is one in which the pixel value is used to directly produce the output colour without the use of a color look-up table and also where the pixel stored in consecutive memory locations. The format allows additional bits to be stored along with the color bits to provide support for additional features such as masks, Z-buffers, linear keys, etc. The format is designed to allow different colour formats to be stored such as RGB, RGBA, YCM and YCMB with varying depths supported. Bit ordering will be most significant bit first. ** CHUNKS ************************************************************ Chunk ID : DGBL (Deep GloBaL information) Chunk purpose : Provide global information of relevance to all the data contained in the file. DGBL will always be the first chunk in the file. Chunk description : Used to provide information that is constant for all contents of the file. One chunk is mandatory at the start of the file. When the file is used to store a group of images it may, in exceptional circum- stances, be necessary to add additional DGBLchunks. The contents of a DGBL chunk remain valid until anotherDGBL chunk is encountered. **************************************** Chunk ID : DPEL (Deep Pixel ELement) Chunk purpose : Defines the contents of each pixel. Enables the data content to be identified and handled. Data that is unknown or not required can be discared. Chunk description : This chunk is best described by an example : Original data = RGBA 8,8,8,4 DPEL = 4 (number of elements) RED (first element) 8 (bits in element) GREEN (second element) 8 (bits in second element) BLUE (third element) 8 (bits in third element) ALPHA (fourth element) 4 (bits in fourth element) Stored data (binary) = rrrrrrrr gggggggg bbbbbbbb aaaa0000 Note : The pixel has been padded to the next byte boundary. The element must be defined in the order in which they are stored, with the most significant bit first. **************************************** Chunk ID : DLOC (Deep display LOCation) Chunk purpose : Provides information specific to the following DBOD section. Enables image sections to be located within the screen areas individually and allows images with a size different to DisplayWidth and DisplayHeight to be stored. Chunk description : Specifies the width, height and where to place the following Deep data BODy. If no DLOC is encountered before a DBOD, the DisplayWidth and DisplayHeight parameters will be used as the DBOD image data dimensions. The contents of a DLOC chunk remain valid until another DLOC chunk is encountered. **************************************** Chunk ID : DBOD (Deep BODy) Chunk purpose : Contains the image data. Chunk description : Contains image data compressed by the method defined in DGBL. The image size and the location where it is to be displayed is provided by a DLOC chunk. If no DLOC chunk has been read the data will be displayed in the upper left corner and will be DisplayWidth wide and DisplayHeight high. **************************************** Chunk ID : DCHG (Deep CHanGe buffer) Chunk purpose : Informs the IFF reader that a complete frame has been read. Only required when multiple images are stored for cell animation. Chunk description : When a chunk is encounter the IFF reader knows that a complete frame has been read. The chunk gives the time, from the last frame change, before the frame should be changed again. If the time has already elapsed the frame should be changed immediatly. A FrameRate of 0 will cause the frame changes to occur as fast as possible. A FrameRate of -1 is used to indicate the end of the data for one frame and the start of the next in cases where multiple frames are stored but are not intended for animation. A DCHG chunk is not required when only a single frame is stored. **************************************** Chunk ID : XS24 (eXtra Small 24 bit image) Chunk purpose : Contain a small image which is supposed to be an 24 bit icon of the file. Chunk description : This icon is currently generated (and displayed) by TVPaint3 and Broadcast Painter. The icon should have a maximum size of 64 pixels by 64 pixels. When the creation of the image, it should be PROPORTIONALLY reduced to enter in these dimensions: the biggest dimension (X or Y) of the image should be equal to 64. The small image is NOT compressed. It is a raw format: RGBRGBRGB... with ONLY RGB values. ** FORM DEEP *********************************************************** // chunk DGBL Struct DGBL = { UWORD DisplayWidth, DisplayHeight; // size of source display UWORD Compression; // type of compression UBYTE xAspect, yAspect; // pixel aspect, a ratio w/h }; // chunk DPEL Struct DPEL = { ULONG nElements; // Number of pixel components Struct TypeDepth = { // The TypeDepth structure is repeated times to identify the content // of every pixel. Pixels will always be padded to byte boundaries. // The DBOD chunk will be padded to an even longword boundary. UWORD cType; // type of data UWORD cBitDepth; // Bit depth of this element } typedepth [ Nelements ]; }; // chunk DLOC struct DLOC = { UWORD w,h; // Body width and height in pixels WORD x,y; // Pixel position for this image }; // chunk DBOD pixel (0), pixel (2), pixel (3),... pixel (w-1), pixel (((h-1)*w)),... pixel(h*w-1) // chunk DCHG struct DCHG = { LONG FrameRate; // Animation control when multiple images are stored // FrameRate - milliseconds between frames changes }; // chunk TVDC struct TVDC = { WORD Table[16]; }; // chunk XS24 struct XS24 = { WORD Width,Height; WORD type; /* type MUST BE equal to 0 (zero) */ }; **************************************** Compressions currently defined : NOCOMPRESSION = 0 RUNLENGHT = 1 Reserved = 2 Reserved = 3 Reserved = 4 DELTA or TVDC = 5 Reserved = 6 Reserved = 7 Ctype currently defined : RED = 1 GREEN = 2 BLUE = 3 ALPHA = 4 YELLOW = 5 CYAN = 6 MAGENTA = 7 BLACK = 8 MASK = 9 ZBUFFER = 10 OPACITY = 11 LINEARKEY= 12 Reserved = 13 Reserved = 14 Reserved = 15 Reserved = 16 DENSITY = 17 ***** DELTA decompression routine ************************************ Routine de décompactage du format TVDC. Notez que la compression est faite ligne à ligne pour chaque élément du chunk DPEL. Pour RGBA on trouve une ligne Rouge, une ligne Verte, etc... Here is a decompression routine for the DELAT format. Note that the compression is made line by line for each element of the DPEL chunk. For RGBA, there is a red line, a green line, etc... CDepackTVDC(source,dest,table,size) UBYTE *source; UBYTE *dest; WORD *table; int size; { int i; int d; int pos=0; UBYTE v=0; for(i=0;i<size;i++) { d=source[pos>>1]; if(pos++ & 1) d&=0xf; else d >>=4; v+=table[d]; dest[i]=v; if(!table[d]) { d=source[pos>>1]; if(pos++ & 1) d&=0xf; else d >>=4; while(d--) dest[++i]=v; } } return((pos+1)/2); } ***** DEEP decompression routine ************************************ Routine de décompactage du format DEEP. Notez que la compression est faite ligne à ligne pour chaque pixel. Here is a decompression routine for the DEEP format. Note that the compression is made LINE by LINE for each pixel. UBYTE *DecodeDeep(UBYTE *source,Pixel *point,int size) { int a,b; while(size>0) { a = *((BYTE*)source++); if(a == -128) { /* nothing */ } else if(a>=0) { a = a + 1; memcpy(point,source,a*sizeof(Pixel)); source += sizeof(Pixel)*a; point += a; size -= a; } else { a = -a + 1; b=a; while(b--) { memcpy(point,source,sizeof(Pixel)) source += sizeof(Pixel); } point += a; size -= a; } } return(source); }