To obtain the SMPTE specification, contact SMPTE directly at +1.914.761.1100 and ask for the specification ANSI/SMPTE 268M-1994, SMPTE Standard for File Format for Digital Moving-Picture Exchange (DPX), v 1.0, 18 February 1994. It is 14 pages, and costs $18.
This information provided here is for review purposes only. Although every attempt has been made to ensure accuracy, no guarantee of such is written or implied. This site is in no way responsible or liable for any damages arising from the use of this information. Please obtain the appropriate specifications for complete information.
Overview of the DPX File Structure
A DPX image consists of 4 parts:
Generic Image
Data
Image
Information Header
Orientation Header
Film Industry Header
Television Industry
Header
typedef struct file_information
{
U32 magic_num; /* magic number 0x53445058 (SDPX) or 0x58504453 (XPDS) */
U32 offset; /* offset to image data in bytes */
ASCII vers[8]; /* which header format version is being used (v1.0)*/
U32 file_size; /* file size in bytes */
U32 ditto_key; /* read time short cut - 0 = same, 1 = new */
U32 gen_hdr_size; /* generic header length in bytes */
U32 ind_hdr_size; /* industry header length in bytes */
U32 user_data_size; /* user-defined data length in bytes */
ASCII file_name[100]; /* iamge file name */
ASCII create_time[24]; /* file creation date "yyyy:mm:dd:hh:mm:ss:LTZ" */
ASCII creator[100]; /* file creator's name */
ASCII project[200]; /* project name */
ASCII copyright[200]; /* right to use or copyright info */
U32 key; /* encryption ( FFFFFFFF = unencrypted ) */
ASCII Reserved[104]; /* reserved field TBD (need to pad) */
} FileInformation;
typedef struct _image_information
{
U16 orientation; /* image orientation */
U16 element_number; /* number of image elements */
U32 pixels_per_line; /* or x value */
U32 lines_per_image_ele; /* or y value, per element */
struct _image_element
{
U32 data_sign; /* data sign (0 = unsigned, 1 = signed ) */
/* "Core set images are unsigned" */
U32 ref_low_data; /* reference low data code value */
R32 ref_low_quantity; /* reference low quantity represented */
U32 ref_high_data; /* reference high data code value */
R32 ref_high_quantity;/* reference high quantity represented */
U8 descriptor; /* descriptor for image element */
U8 transfer; /* transfer characteristics for element */
U8 colorimetric; /* colormetric specification for element */
U8 bit_size; /* bit size for element */
U16 packing; /* packing for element */
U16 encoding; /* encoding for element */
U32 data_offset; /* offset to data of element */
U32 eol_padding; /* end of line padding used in element */
U32 eo_image_padding; /* end of image padding used in element */
ASCII description[32]; /* description of element */
} image_element[8]; /* NOTE THERE ARE EIGHT OF THESE */
U8 reserved[52]; /* reserved for future use (padding) */
} Image_Information;
typedef struct _image_orientation
{
U32 x_offset; /* X offset */
U32 y_offset; /* Y offset */
R32 x_center; /* X center */
R32 y_center; /* Y center */
U32 x_orig_size; /* X original size */
U32 y_orig_size; /* Y original size */
ASCII file_name[100]; /* source image file name */
ASCII creation_time[24]; /* source image creation date and time */
ASCII input_dev[32]; /* input device name */
ASCII input_serial[32]; /* input device serial number */
U16 border[4]; /* border validity (XL, XR, YT, YB) */
U32 pixel_aspect[2]; /* pixel aspect ratio (H:V) */
U8 reserved[28]; /* reserved for future use (padding) */
} Image_Orientation;
typedef struct _motion_picture_film_header
{
ASCII film_mfg_id[2]; /* film manufacturer ID code (2 digits from film edge code) */
ASCII film_type[2]; /* file type (2 digits from film edge code) */
ASCII offset[2]; /* offset in perfs (2 digits from film edge code)*/
ASCII prefix[6]; /* prefix (6 digits from film edge code) */
ASCII count[4]; /* count (4 digits from film edge code)*/
ASCII format[32]; /* format (i.e. academy) */
U32 frame_position; /* frame position in sequence */
U32 sequence_len; /* sequence length in frames */
U32 held_count; /* held count (1 = default) */
R32 frame_rate; /* frame rate of original in frames/sec */
R32 shutter_angle; /* shutter angle of camera in degrees */
ASCII frame_id[32]; /* frame identification (i.e. keyframe) */
ASCII slate_info[100]; /* slate information */
U8 reserved[56]; /* reserved for future use (padding) */
} Motion_Picture_Film;
Television typedef struct _television_header
{
U32 tim_code; /* SMPTE time code */
U32 userBits; /* SMPTE user bits */
U8 interlace; /* interlace ( 0 = noninterlaced, 1 = 2:1 interlace*/
U8 field_num; /* field number */
U8 video_signal; /* video signal standard (table 4)*/
U8 unused; /* used for byte alignment only */
R32 hor_sample_rate; /* horizontal sampling rate in Hz */
R32 ver_sample_rate; /* vertical sampling rate in Hz */
R32 frame_rate; /* temporal sampling rate or frame rate in Hz */
R32 time_offset; /* time offset from sync to first pixel */
R32 gamma; /* gamma value */
R32 black_level; /* black level code value */
R32 black_gain; /* black gain */
R32 break_point; /* breakpoint */
R32 white_level; /* reference white level code value */
R32 integration_times; /* integration time(s) */
U8 reserved[76]; /* reserved for future use (padding) */
} Television_Header;
Data is the actual user-defined data. The format of the field is not defined by the DPX standard and the data in this field may be up to one megabyte (1,048,576 bytes) in length.
typedef struct _image_data_element
{
U8 * 4 *Data;
} Image_Data_Element;
"The DPX format stores image data by pixels, separating each pixel into its component values (also called samples in other formats) and storing each value.
All components must be the same size across all elements. Valid component sizes are 1-, 8-, 10-, 12-, and 16-bit integers and 32- and 64-bit reals (IEEE floating-point). All components must be stored as words using 32-bit boundaries."
Value Components (and order in unpacked stream) 0 User defined (or unspecified single component) 1 Red (R) 2 Green (G) 3 Blue (B) 4 Alpha (matte) 56 Luminance (Y) 7 Chrominance (CB, CR, subsampled by two) 8 Depth (Z) 9 Composite video 10 - 49 Reserved for future single components 50 R,G,B 51 R,G,B,alpha 52 Alpha, B, G, R 53 - 99 Reserved for future RGB ++ formats 100 CB, Y, CR, Y (4:2:2) -- based on SMPTE 125M 101 CB, Y, a, CR, Y, a (4:2:2:4) 102 CB, Y, CR (4:4:4) 103 CB, Y, CR, a (4:4:4:4) 104 - 149 Reserved for future CBYCR ++ formats 150 User-defined 2 component element 151 User-defined 3 component element 152 User-defined 4 component element 153 User-defined 5 component element 154 User-defined 6 component element 155 User-defined 7 component element 156 User-defined 8 component element 157 - 254 Reserved for future formats
Cineon File Format Version 4.5 for Digital Film
Images
Critical areas of information that the image file header needs to convey are:
U8 unsigned 8 bit integer (FF hex) U16 unsigned 16 bit integer (FFFF hex) U32 unsigned 32 bit integer (FFFFFFFF hex) S32 signed 32 bit integer (80000000 hex) R32 32 bit real number (7F800000 hex (+ infinity)) ASCII (NULL 00 hex)The assumption the relation of code value to data metric is linear is made. Therefore, given the minimum and maximum code values for a given (colour) channel, and the associated metric quantity represented, any value in between can be found via linear interpolation. For example, if the minimum code value is 0, representing 0.2 log exposure, and the maximum code value is 1169 representing 3.4 log exposure, then a code value of 584 represents 1.8 log exposure.
Field # Offset Length Type Content 1.1 0 4 U32 Magic number (802A5FD7 - hex) indicates the start of image file and byte ordering 1.2 4 4 U32 Offset to image data in bytes 1.3 8 4 U32 Generic (fixed format) section header length in bytes 1.4 12 4 U32 Industry specific (fixed format) section header length in bytes 1.5 16 4 U32 Length in bytes of variable length section 1.6 20 4 U32 Total image file size in bytes (includes header, image data and padding if any) 1.7 24 8 ASCII Version number of header format 1.8 32 100 ASCII Image file name 1.9 132 12 ASCII Creation date - eg "yyyy:mm:dd" 1.10 144 12 ASCII Creation time - eg "hh:mm:ssxxx" (xxx = time zone (eg. EST)) 1.11 156 36 TBD Reserved for future use
Field # Offset Length Type Content 1.12 192 1 U8 Image orientation val line scan dir page scan direction --- ------------- ------------------- 0 left to right top to bottom 1 left to right bottom to top 2 right to left top to bottom 3 right to left bottom to top 4 top to bottom left to right 5 top to bottom right to left 6 bottom to top left to right 7 bottom to top right to left 1.13 193 1 U8 Number of channels ( 1 - 8 ) 1.13.1 164 2 U8*2 UNUSED ( 2 byte space for word alignment ) 1.14.1 196 1 U8 *Channel 1 designator - Byte 0 (see table 1 ) 1.14.2 197 1 U8 *Channel 1 designator - Byte 1 (see table 1 ) 1.14.3 198 1 U8 *Bits per pixel - channel 1 1.14.4 199 1 U8 UNUSED ( 1 byte space for word alignment ) 1.14.5 200 4 U32 *Pixels per line - channel 1 1.14.6 204 4 U32 *Lines per image - channel 1 1.14.7 208 4 R32 *Minimum data value - channel 1 1.14.8 212 4 R32 *Minimum quantity represented - channel 1 1.14.9 216 4 32 *Maximum data value - channel 1 1.14.10 220 4 32 *Maximum quantity represented - channel 1 1.15 224 28 structure Channel 2 specifier (same as channel 1) 1.16 252 28 structure Channel 3 specifier (same as channel 1) 1.17 280 28 structure Channel 4 specifier (same as channel 1) 1.18 308 28 structure Channel 5 specifier (same as channel 1) 1.19 336 28 structure Channel 6 specifier (same as channel 1) 1.20 364 28 structure Channel 7 specifier (same as channel 1) 1.21 392 28 structure Channel 8 specifier (same as channel 1) 1.22 420 8 R32*2 White point (colour temperature) - x, y pair 1.23 428 8 R32*2 Red primary chromaticity - x, y pair 1.24 436 8 R32*2 Green primary chromaticity - x, y pair 1.25 444 8 R32*2 Blue primary chromaticity - x, y pair 1.26 452 200 ASCII Label text (other label info in user area - font, size, location) 1.27 652 28 TBD Reserved for future use
Field # Offset Length Type Content 1.28 680 1 U8 Data interleave (if all channels are not the same sptial resolution, data interleave must be 2, channel interleave) 0 = pixel interleave ( rgbrgbrgbrgb... ) 1 = line interleave (rrr.ggg.bbb.rrr.ggg.bbb.) 2 = channel interleave (rrr...ggg...bbb...) 3 - 254 = user defined 1.29 681 1 U8 Packing (see note 1 ) 0 = user all bits( bitfields) - TIGHTEST - no byte, word or long word boundaries 1 = byte ( 8 bit ) boundaries - lef justified 2 = byte ( 8 bit ) boundaries - right justified 3 = word (16 bit) bondaries - left justified 4 = word ( 16 bit) boundaries - right justified 5 = longword ( 32 bit ) boundaries - left justified 6 = longword ( 32 bit ) boundaries - right justified High order bit = 0 - pack at most one pixel per cell High order bit = 1 - pack at many fields as possible per cell 1.30 682 1 U8 Data signed or unsigned 0 = unsigned 1 = signed 1.31 683 1 U8 Image sense 0 = positive image 1 = negative image 1.32 684 4 U32 End of line padding - number of bytes 1.33 688 4 U32 End of channel padding - number of bytes 1.34 692 20 TBD Reserved for future use
Field # Offset Length Type: Content: 1.35 712 4 S32 X offset (correlate digital data to source media) 1.36 716 4 S32 Y offset (correlate digital data to source media) 1.37 720 100 ASCII Image filename 1.38 820 12 ASCII Creation date (i.e. "yyyy:mm:dd" ) 1.39 832 12 ASCII Creation time (i.e. "hh:mm:ssxxx" where xxx is time zone (i.e PST)) 1.40 844 64 ASCII Input device 1.41 908 32 ASCII Input device model number 1.42 940 32 ASCII Input device serial number 1.43 972 4 R32 X input device pitch (samples/mm) (X determined by image orientation) 1.44 976 4 R32 Y input device pitch (samples/mm) (Y determined by image orientation) 1.45 980 4 R32 Image gamma of capture device 1.46 984 40 TBD Reserved for future use
2.1 1024 1 U8 2.2 1025 1 U8 2.3 1026 1 U8 2.4 1027 1 U8 2.5 1028 4 U32 2.6 1032 4 U32 2.7 1036 32 ASCII 2.8 1068 4 U32 2.9 1072 4 R32 2.10 1076 32 ASCII 2.11 1108 2000 ASCII 2.12 1308 740 TBD Reserved for future use
Field Offset Length Type Content 3.0 2048 --- --- Reserved for customer use - compression, processing log, etc.Note: for Cineon images, this section is currently defined to contain the postage stamp image (an image 96x64x3 channels (18 KBytes for 8 bit mode) oriented correctly for display).
Byte 0 0 = Universal metric 1 - 254 = vendor specific (i.e. 1 = Kodak); Byte 1 if Byte 0 = 0 Universal Metric 0 = B & W 1 = red (r,g,b printing density) 2 = green (r,g,b printing density) 3 = blue (r,g,b printing density) 4 = red (r,g,b CCIR XA/11) 5 = green (r,g,b CCIR XA/11) 6 = blue (r,g,b CCIR XA/11) 7 - 254 TBD - reserved if 0< Byte 0 < 255 0 - 254 Vendor defined
CELL to be a
BYTE (8 bits), WORD (16 bits) or LONGWORD
(32bits).
Define a FIELD to be one occurence of a channel value. For
example, with 3 channels (r,g,b), pixel interleaved, field 1 is r1,
field 2 is g1, field 3 is b1, field 4 is
r2, etc. With 3 channels (r, g, b), channel interleaved, field 1 is
r1, field 2 is r2, field 3 is r3, etc.
The high order bit of the packing specifier either restricts packing to at most one pixel (n channels) per cell, or allows fields from adjacent pixels to spill over cell boundaries.
If number of channels is > 1 AND data interleave = 0 (pixel interleave)
n = number of channels
Pack as many fields into the cell as posssible up to n fields, with appropriate justification, then align on the next cell boundary.
Pack as many fields into the cell as possible, with appropriate justification, then alighn on the next cell boundary.
Number of channels = 4 6 bits 6 bits 6 bits 6 bits 8 bits
All channels, 6 bits deep field1 field2 field3 field4 empty
Data interleave = 0 ch1[1] ch2[1] ch3[1] ch4[1] xxxxxxxx
Packing = 5 (High order bit clear)
Number of channels = 4 6 bits 6 bits 6 bits 6 bits 6 bits 2 bits
All channels, 6 bits deep field1 field2 field3 field4 field5 empty
Data interleave = 0 ch1[1] ch2[1] ch3[1] ch4[1] ch1[2]xx
Packing = 5 (High order bit set)
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