Extended Display Identification Data

Background

The channel for transmitting the EDID from the display to the graphics card is usually the I²C-bus, defined in DDC2B (DDC1 used a different serial format which never gained popularity).

Before DDC and EDID were defined, there was no standard way for a graphics card to know what kind of display device it was connected to. Some VGA connectors in personal computers provided a basic form of identification by connecting one, two or three pins to ground, but this coding was not standardized.

The EDID is often stored in the monitor in a memory device called a serial PROM (programmable read-only memory) or EEPROM (electrically erasable PROM) and is accessible via the I²C-bus at address 0x50. The EDID PROM can often be read by the host PC even if the display itself is turned off.

Many software packages can read and display the EDID information, such as read-edid for Linux and DOS, PowerStrip for Microsoft Windows and XFree86 for Linux and BSD unix. Mac OS X natively reads EDID information and programs such as SwitchResX or DisplayConfigX can display the information as well as use it to define custom resolutions.

Enhanced EDID (E-EDID)

Enhanced EDID was introduced at the same time as E-DDC; it introduced EDID structure version 1.3 which supports multiple extensions blocks and deprecated EDID version 2.0 structure (although it can be supported as an extension). Data fields for preferred timing, range limits, monitor name are required in E-EDID. E-EDID also supports dual GTF timings and aspect ratio change.

With the use of extensions, E-EDID string can be lengthened up to 32 KBytes.

EDID Extensions assigned by VESA

Timing Extension (00h)

Additional Timing Data Block (CEA EDID Timing Extension) (02h)

Video Timing Block Extension (VTB-EXT) (10h)

EDID 2.0 Extension (20h)

Display Information Extension (DI-EXT) (40h)

Localized String Extension (LS-EXT) (50h)

Microdisplay Interface Extension (MI-EXT) (60h)

Display Transfer Characteristics Data Block (DTCDB) (A7h, AFh, BFh)

Block Map (F0h)

Display Device Data Block (DDDB) (FFh)

Extension defined by monitor manufacturer (FFh): According to LS-EXT, actual contents varies from manufacturer. However, the value is later used by DDDB.

Revision history

August 1994, DDC standard version 1 – EDID v1.0 structure.

April 1996, EDID standard version 2 – EDID v1.1 structure.

1997, EDID standard version 3 – EDID structures v1.2 and v2.0

February 2000, E-EDID Standard Release A, v1.0 – EDID structure v1.3, EDID structure v2.0 deprecated

September 2006 – E-EDID Standard Release A, v2.0 – EDID structure v1.4

Limitations

Some graphics card drivers have historically coped poorly with the EDID, using only its standard timing descriptors rather than its Detailed Timing Descriptors (DTDs). Even in cases where the DTDs were read, the drivers are/were still often limited by the standard timing descriptor limitation that the horizontal/vertical resolutions must be evenly divisible by 8. This means that many graphics cards cannot express the native resolutions of the most common wide screen flat panel displays and liquid crystal display televisions. The number of vertical pixels is calculated from the horizontal resolution and the selected aspect ratio. To be fully expressible, the size of wide screen display must thus be a multiple of 16×9 pixels. For 1366×768 pixel Wide XGA panels the nearest resolution expressible in the EDID standard timing descriptor syntax is 1360×765 pixels, typically leading to 3 pixel thin black bars. Specifying 1368 pixels as the screen width would yield an unnatural screen height of 769.5 pixels.

Many Wide XGA panels do not advertise their native resolution in the standard timing descriptors, instead offering only a resolution of 1280×768. Some panels advertise a resolution only slightly smaller than the native, such as 1360×765. For these panels to be able to show a pixel perfect image, the EDID data must be ignored by the display driver or the driver must correctly interpret the DTD and be able to resolve resolutions whose size is not divisible by 8. Special programs are available to override the standard timing descriptors from EDID data. Even this is not always possible however, as some vendors' graphics drivers (notably those of Intel) require specific registry hacks to implement custom resolutions, which can make it very difficult to use the screen's native resolution.

EDID 1.3 data format

When used for another descriptor, the pixel clock and some other bytes are set to 0:

Currently defined descriptor types are:

0xFF: Monitor serial number (text)

0xFE: Unspecified text (text)

0xFD: Monitor range limits. 6- or 13-byte binary descriptor.

0xFC: Monitor name (text), padded with 0A 20 20.

0xFB: Additional white point data. 2× 5-byte descriptors, padded with 0A 20 20.

0xFA: Additional standard timing identifiers. 6× 2-byte descriptors, padded with 0A.

EIA/CEA-861 extension block

The CEA EDID Timing Extension was first introduced in EIA/CEA-861, and has since been updated several times, most notably with the −861B revision (which was version 3 of the extension, adding Short Video Descriptors and advanced audio capability/configuration information), −861D (published in July 2006 and containing updates to the audio segments), −861E, and −861F which was published on June 4, 2013. According to Brian Markwalter, senior vice president, research and standards, CEA, −861F "includes a number of noteworthy enhancements, including support for several new Ultra HD and widescreen video formats and additional colorimetry schemes.”

Version 1 (as defined in −861) allowed the specification of video timings only through the use of 18-byte Detailed Timing Descriptors (DTD) (as detailed in EDID 1.3 data format above). In all cases, the "preferred" timing should be the first DTD listed in a CEA EDID Timing Extension.

Version 2 (as defined in −861A) added the capability to designate a number of DTDs as "native" and also included some "basic discovery" functionality for whether the display device contains support for "basic audio", YCbCr pixel formats, and underscan.

Version 3 (from the −861B spec) allows two different ways to specify the timings of available digital TV formats: As in Version 1 & 2 by the use of 18-byte DTDs, or by the use of the Short Video Descriptor (SVD) (see below). HDMI 1.0 -1.3c uses this version.

Version 3 also includes four new optional types of data blocks: Video Data Blocks containing the aforementioned Short Video Descripter (SVD), Audio Data Blocks containing Short Audio Descriptors (SAD), Speaker Allocation Data Blocks containing information about the speaker configuration of the display device, and Vendor Specific Data Blocks which can contain information specific to a given vendor's use.

CEA EDID Timing Extension data format -- Version 3

Byte sequence 00: Extension tag (which kind of extension block this is); 02h for CEA EDID 01: Revision number (Version number); 03h for Version 3 02: Byte number (decimal) within this block where the 18-byte DTDs begin. If no non-DTD data is present in this extension block, the value should be set to 04h (the byte after next). If set to 00h, there are no DTDs present in this block and no non-DTD data. 03: Number of Native DTDs present, other Version 2+ information bit 7: 1 if display supports underscan, 0 if not bit 6: 1 if display supports basic audio, 0 if not bit 5: 1 if display supports YCbCr 4:4:4, 0 if not bit 4: 1 if display supports YCbCr 4:2:2, 0 if not bit 3..0: total number of native formats in the DTDs included in this block 04: Start of Data Block Collection. If byte 02 is set to 04h, this is where the DTD collection begins. If byte 02 is set to another value, byte 04 is where the Data Block Collection begins, and the DTD collection follows immediately thereafter. The Data Block Collection contains one or more data blocks detailing video, audio, and speaker placement information about the display. The blocks can be placed in any order, and the initial byte of each block defines both its type and its length: bit 7..5: Block Type Tag (1 is audio, 2 is video, 3 is vendor specific, 4 is speaker allocation, all other values Reserved) bit 4..0: Total number of bytes in this block following this byte Once one data block has ended, the next byte is assumed to be the beginning of the next data block. This is the case until the byte (designated in Byte 02, above) where the DTDs are known to begin. '''Audio Data Blocks''' contain one or more 3-byte Short Audio Descriptors (SADs). Each SAD details audio format, channel number, and bitrate/resolution capabilities of the display as follows: SAD Byte 1 (format and number of channels): bit 7: Reserved (0) bit 6..3: Audio format code 1 = Linear Pulse Code Modulation (LPCM) 2 = AC-3 3 = MPEG1 (Layers 1 and 2) 4 = MP3 5 = MPEG2 6 = AAC 7 = DTS 8 = ATRAC 0, 15: Reserved 9 = One-bit audio aka SACD 10 = DD+ 11 = DTS-HD 12 = MLP/Dolby TrueHD 13 = DST Audio 14 = Microsoft WMA Pro bit 2..0: number of channels minus 1 (i.e. 000 = 1 channel; 001 = 2 channels; 111 = 8 channels) SAD Byte 2 (sampling frequencies supported): bit 7: Reserved (0) bit 6: 192kHz bit 5: 176kHz bit 4: 96kHz bit 3: 88kHz bit 2: 48kHz bit 1: 44kHz bit 0: 32kHz SAD Byte 3 (bitrate): For LPCM, bits 7:3 are reserved and the remaining bits define bit depth bit 2: 24 bit bit 1: 20 bit bit 0: 16 bit For all other sound formats, bits 7..0 designate the maximum supported bitrate divided by 8 kbit/s. '''Video Data Blocks''' will contain one or more 1-byte Short Video Descriptors (SVDs). They are decoded as follows: bit 7: 1 to designate that this should be considered a "native" resolution, 0 for non-native bit 6..0: index value to a table of standard resolutions/timings from CEA/EIA-861F: Code Picture Pixel Short Aspect Aspect Name Ratio Ratio HxV @ F 1 DMT0659 4:3 640x480p @ 59.94/60 Hz 2 480p 4:3 8:9 720x480p @ 59.94/60 Hz 3 480pH 16:9 32:37 720x480p @ 59.94/60 Hz 4 720p 16:9 1:1 1280x720p @ 59.94/60 Hz 5 1080i 16:9 1:1 1920x1080i @ 59.94/60 Hz 6 480i 4:3 8:9 720(1440)x480i @ 59.94/60 Hz 7 480iH 16:9 32:37 720(1440)x480i @ 59.94/60 Hz 8 240p 4:3 8:9 720(1440)x240p @ 59.94/60 Hz 9 240pH 16:9 32:37 720(1440)x240p @ 59.94/60 Hz 10 480i4x 4:3 8:9 (2880)x480i @ 59.94/60 Hz 11 480i4xH 16:9 32:37 (2880)x480i @ 59.94/60 Hz 12 240p4x 4:3 8:9 (2880)x240p @ 59.94/60 Hz 13 240p4xH 16:9 32:37 (2880)x240p @ 59.94/60 Hz 14 480p2x 4:3 8:9 1440x480p @ 59.94/60 Hz 15 480p2xH 16:9 32:37 1440x480p @ 59.94/60 Hz 16 1080p 16:9 1:1 1920x1080p @ 59.94/60 Hz 17 576p 4:3 16:15 720x576p @ 50 Hz 18 576pH 16:9 64:45 720x576p @ 50 Hz 19 720p50 16:9 1:1 1280x720p @ 50 Hz 20 1080i25 16:9 1:1 1920x1080i @ 50 Hz* 21 576i 4:3 16:15 720(1440)x576i @ 50 Hz 22 576iH 16:9 64:45 720(1440)x576i @ 50 Hz 23 288p 4:3 16:15 720(1440)x288p @ 50 Hz 24 288pH 16:9 64:45 720(1440)x288p @ 50 Hz 25 576i4x 4:3 16:15 (2880)x576i @ 50 Hz 26 576i4xH 16:9 64:45 (2880)x576i @ 50 Hz 27 288p4x 4:3 16:15 (2880)x288p @ 50 Hz 28 288p4xH 16:9 64:45 (2880)x288p @ 50 Hz 29 576p2x 4:3 16:15 1440x576p @ 50 Hz 30 576p2xH 16:9 64:45 1440x576p @ 50 Hz 31 1080p50 16:9 1:1 1920x1080p @ 50 Hz 32 1080p24 16:9 1:1 1920x1080p @ 23.98/24 Hz 33 1080p25 16:9 1:1 1920x1080p @ 25 Hz 34 1080p30 16:9 1:1 1920x1080p @ 29.97/30 Hz 35 480p4x 4:3 8:9 (2880)x480p @ 59.94/60 Hz 36 480p4xH 16:9 32:37 (2880)x480p @ 59.94/60 Hz 37 576p4x 4:3 16:15 (2880)x576p @ 50 Hz 38 576p4xH 16:9 64:45 (2880)x576p @ 50 Hz 39 1080i25 16:9 1:1 1920x1080i @ 50 Hz* (1250 Total) 40 1080i50 16:9 1:1 1920x1080i @ 100 Hz 41 720p100 16:9 1:1 1280x720p @ 100 Hz 42 576p100 4:3 8:9 720x576p @ 100 Hz 43 576p100H 16:9 32:37 720x576p @ 100 Hz 44 576i50 4:3 16:15 720(1440)x576i @ 100 Hz 45 576i50H 16:9 64:45 720(1440)x576i @ 100 Hz 46 1080i60 16:9 1:1 1920x1080i @ 119.88/120 Hz 47 720p120 16:9 1:1 1280x720p @ 119.88/120 Hz 48 480p119 4:3 16:15 720x480p @ 119.88/120 Hz 49 480p119H 16:9 64:45 720x480p @ 119.88/120 Hz 50 480i59 4:3 8:9 720(1440)x480i @ 119.88/120 Hz 51 480i59H 16:9 32:37 720(1440)x480i @ 119.88/120 Hz 52 576p200 4:3 16:15 720x576p @ 200 Hz 53 576p200H 16:9 64:45 720x576p @ 200 Hz 54 576i100 4:3 16:15 720(1440)x576i @ 200 Hz 55 576i100H 16:9 64:45 720(1440)x576i @ 200 Hz 56 480p239 4:3 8:9 720x480p @ 239.76/240 Hz 57 480p239H 16:9 32:37 720x480p @ 239.76/240 Hz 58 480i119 4:3 8:9 720(1440)x480i @ 239.76/240 Hz 59 480i119H 16:9 32:37 720(1440)x480i @ 239.76/240 Hz 60 720p24 16:9 1:1 1280x720p @ 23.98/24 Hz 61 720p25 16:9 1:1 1280x720p @ 25Hz 62 720p30 16:9 1:1 1280x720p @ 29.97/30 Hz 63 1080p120 16:9 1:1 1920x1080p @ 119.88/120 Hz 64 1080p100 16:9 1:1 1920x1080p @ 100 Hz 65 720p24 64:27 4:3 1280x720p @ 23.98/24 Hz 66 720p25 64:27 4:3 1280x720p @ 25Hz 67 720p30 64:27 4:3 1280x720p @ 29.97/30 Hz 68 720p50 64:27 4:3 1280x720p @ 50 Hz 69 720p 64:27 4:3 1280x720p @ 59.94/60 Hz 70 720p100 64:27 4:3 1280x720p @ 100 Hz 71 720p120 64:27 4:3 1280x720p @ 119.88/120 Hz 72 1080p24 64:27 4:3 1920x1080p @ 23.98/24 Hz 73 1080p25 64:27 4:3 1920x1080p @ 25Hz 74 1080p30 64:27 4:3 1920x1080p @ 29.97/30 Hz 75 1080p50 64:27 4:3 1920x1080p @ 50 Hz 76 1080p 64:27 4:3 1920x1080p @ 59.94/60 Hz 77 1080p100 64:27 4:3 1920x1080p @ 100 Hz 78 1080p120 64:27 4:3 1920x1080p @ 119.88/120 Hz 79 720p24 64:27 64:63 1680x720p @ 23.98/24 Hz 80 720p25 64:27 64:63 1680x720p @ 25Hz 81 720p30 64:27 64:63 1680x720p @ 29.97/30 Hz 82 720p50 64:27 64:63 1680x720p @ 50 Hz 83 720p 64:27 64:63 1680x720p @ 59.94/60 Hz 84 720p100 64:27 64:63 1680x720p @ 100 Hz 85 720p120 64:27 64:63 1680x720p @ 119.88/120 Hz 86 1080p24 64:27 1:1 2560x1080p @ 23.98/24 Hz 87 1080p25 64:27 1:1 2560x1080p @ 25Hz 88 1080p30 64:27 1:1 2560x1080p @ 29.97/30 Hz 89 1080p50 64:27 1:1 2560x1080p @ 50 Hz 90 1080p 64:27 1:1 2560x1080p @ 59.94/60 Hz 91 1080p100 64:27 1:1 2560x1080p @ 100 Hz 92 1080p120 64:27 1:1 2560x1080p @ 119.88/120 Hz 93 2160p24 16:9 1:1 3840x2160p @ 23.98/24 Hz 94 2160p25 16:9 1:1 3840x2160p @ 25Hz 95 2160p30 16:9 1:1 3840x2160p @ 29.97/30 Hz 96 2160p50 16:9 1:1 3840x2160p @ 50 Hz 97 2160p 16:9 1:1 3840x2160p @ 59.94/60 Hz 98 2160p24 256:135 1:1 4096x2160p @ 23.98/24 Hz 99 2160p25 256:135 1:1 4096x2160p @ 25Hz 100 2160p30 256:135 1:1 4096x2160p @ 29.97/30 Hz 101 2160p50 256:135 1:1 4096x2160p @ 50 Hz 102 2160p 256:135 1:1 4096x2160p @ 59.94/60 Hz 103 2160p24 64:27 4:3 3840x2160p @ 23.98/24 Hz 104 2160p25 64:27 4:3 3840x2160p @ 25Hz 105 2160p30 64:27 4:3 3840x2160p @ 29.97/30 Hz 106 2160p50 64:27 4:3 3840x2160p @ 50 Hz 107 2160p 64:27 4:3 3840x2160p @ 59.94/60 Hz 0, 108 - 127 Reserved *Short video descriptors 20 & 39 are both 1920x1080i@50 16:9 but differ in the amount of vertical total lines which are 1125 and 1250, respectively. Notes: Parentheses indicate instances where pixels are repeated to meet the minimum speed requirements of the interface. For example, in the 720X240p case, the pixels on each line are double-clocked. In the (2880)X480i case, the number of pixels on each line, and thus the number of times that they are repeated, is variable, and is sent to the DTV monitor by the source device. Increased Hactive expressions include “2x” and “4x” indicate two and four times the reference resolution, respectively. The CEA/EIA-861/A standard included only numbers 1-7 and numbers 17-22 above(but not as short video descriptors which were introduced in CEA/EIA-861B) and are considered primary video format timings. The CEA/EIA-861B standard included the first 34 short video descriptors above. The CEA/EIA-861D standard included the first 59 short video descriptors above. The CEA/EIA-861E standard included the first 64 short video descriptors above. HDMI 1.0 to HDMI 1.2a uses the CEA-861-B video standard, HDMI 1.3 to HDMI 1.3c uses the CEA-861-D video standard, HDMI 1.4 uses the CEA/EIA-861E video standard. HDMI 2.0 uses the CEA/EIA-861F standard. A '''Vendor Specific Data Block''' (if any) contains as its first three bytes the vendor's IEEE 24-bit registration number, LSB first. For HDMI, it is always 00-0C-03 for HDMI Licensing, LLC. It is followed by a two byte source physical address, LSB first. The source physical address provides the CEC physical address for upstream CEC devices. The remainder of the Vendor Specific Data Block is the "data payload",which can be anything the vendor considers worthy of inclusion in this EDID extension block. HDMI 1.3a specifies some requirements for the data payload. See that spec for detailed info on these bytes: VSD Byte 1-3 IEEE Registration Identifier (LSB First) VSD Byte 4-5 Components of Source Physical Address (See section 8.7 of HDMI 1.3a) VSD Byte 6 (optional) (bits are set if sink supports...): bit 7: Supports_AI (...a function that needs info from ACP or ISRC packets) bit 6: DC_48bit (...16-bit-per-channel deep color) bit 5: DC_36bit (...12-bit-per-channel deep color) bit 4: DC_30bit (...10-bit-per-channel deep color) bit 3: DC_Y444 (...4:4:4 in deep color modes) bit 2: Reserved (0) bit 1: Reserved (0) bit 0: DVI_Dual (...DVI Dual Link Operation) VSD Byte 7 (optional) If non-zero (Max_TMDS_Frequency / 5mhz) VSD Byte 8 (optional) (latency fields indicators): bit 7: latency_fields (set if latency fields are present) bit 6: i_latency_fields (set if interlaced latency fields are present; if set four latency fields will be present, 0 if bit 7 is 0) bits 5-0: Reserved (0) VSD Byte 9 (optional) Video Latency (if indicated, value=1+ms/2 with a max of 251 meaning 500ms) VSD Byte 10 (optional) Audio Latency (video delay for progressive sources, same units as above) VSD Byte 11 (optional) Interlaced Video Latency (if indicated, same units as above) VSD Byte 12 (optional) Interlaced Audio Latency (video delay for interlaced sources, same units as above) Additional bytes may be present, but the HDMI spec says they shall be zero. If a Speaker Allocation Data Block is present, it will consist of three bytes. The second and third are Reserved (all 0), but the first contains information about which speakers are present in the display device: bit 7: Reserved (0) bit 6: Rear Left Center / Rear Right Center present for 1, absent for 0 bit 5: Front Left Center / Front Right Center present for 1, absent for 0 bit 4: Rear Center present for 1, absent for 0 bit 3: Rear Left / Rear Right present for 1, absent for 0 bit 2: Front Center present for 1, absent for 0 bit 1: LFE present for 1, absent for 0 bit 0: Front Left / Front Right present for 1, absent for 0 Note that for speakers with right and left polarity, it is assumed that both left and right are present. "d": byte (designated in byte 02) where DTDs begin. 18-byte DTD strings continue for an unspecified length (modulo 18) until a "00 00" is as the first bytes of a prospective DTD. At this point, the DTDs are known to be complete, and the start address of the "00 00" can be considered to be "XX" (see below) "XX"-126: Post-DTD padding. Should be populated with 00h 127: Checksum - This byte must be programmed such that the sum of all 128 bytes equals 00h.