Uncompressed video, also called Clean HDMI, is digital video information that has not been compressed, or was not processed with compression on it when the video was captured directly from a digital camera. It stands for the related data stream or the file format used by digital video cameras. The purpose is significant higher quality compared to lossy compression, allowing even resolution upscaling.
The HDMI specification specifies several modes of uncompressed digital video. Although often HD video capable cameras include a HDMI interface for playback or even live preview, the image processor and the video processor of cameras usable for uncompressed video must be able to deliver the full image resolution at the specified frame rate in realtime without any missing frames causing judder. Therefore usable uncompressed video out of HDMI is often called "Clean HDMI".
Currently uncompressed video is supported by Nikon DSLRs with the Expeed 3 (FR) image/video processor (currently Nikon D4, Nikon D800/D800E, Nikon D600, Nikon D7100 and Nikon D5200), the Canon EOS-1D C and professional video cameras like Arri Alexa, which also use proprietary or raw formats.
Characteristics
Due to the high video compression in MPEG encoding, the video quality of uncompressed video delivers even more image resolution and sharpness than the related Raw image format.
It has the further advantage of higher quality due to no motion blur (no motion compensation) and no compression artifacts.
Currently there is no standardized uncompressed video file format except for HDMI, which uses the YCbCr and RGB formats listed below. This makes it necessary to store it best with a related description file about the used resolution and video mode. These files can be combined with lossless compression with the use of file archivers.
Lossless video compression
Lossless video compression can be delivered with a variety of video codecs. In test some codecs performed an average compression of over factor 3.[1]
Practical configuration and recording
Setting up the camera is especially new for DSLR users, as Nikon supports uncompressed video newly.[2] The built in video interface in cameras is mostly an HDMI or Serial digital interface (HD-SDI); converters between both are available.[3]
Video capture interfaces
HDMI and HD-SDI inputs are available[4][5][6] also for 2160p (4K resolution).[7][8] Hard disk drives have to be fast solid-state drives (SSDs) or RAID to be capable of the data-rate.
Wireless video interfaces
Wireless interfaces like Wireless LAN (WLAN, Wi-Fi) are only usable for Full HD with highest speed (IEEE 802.11n-2009). Alternatives are (partly future) interfaces like WirelessHD, WiDi, Wireless Home Digital Interface (WHDI), Wireless HDMI and Wireless Gigabit Alliance.
Uncompressed video recording software
Software for uncompressed video is often supplied with suitable hardware or available as free open source.[9]
Uncompressed video recorder
Portable recorders[10] are a simple and complete solution for receiving and storing uncompressed video. Partly they only record lossy compressed video, often in Apple ProRes 422 or DNxHD codecs.[11][12] Professional recorders support multiple channels of HDMI, DVI and HD-SDI.[13]
Storage and Data Rates for Uncompressed Video
Constant bitrate formula: Uncompressed data rate = color depths * vertical resolution * horizontal resolution * refresh frequency
- Examples
24bit @ 1080i @ 30fps :24*1920*1080*30=1.49 Gbps.
24bit @ 1080p @ 60fps :24*1920*1080*60=2.98 Gbps.
Cameras mostly use the progressive segmented frame format: for example a 25p/30p progressive scan is converted into a 50i/60i interlaced format respectively, but with the identically information. The storage and data rates for uncompressed video are listed below:
525 NTSC uncompressed
8 bit @ 720 x 486 @ 29.97fps = 20 MB per/sec, or 70 GB per/hr.
10 bit @ 720 x 486 @ 29.97fps = 27 MB per/sec, or 94 GB per/hr.
625 PAL uncompressed
8 bit @ 720 x 576 @ 25fps = 20 MB per/sec, or 70 GB per/hr.
10 bit @ 720 x 576 @ 25fps = 26 MB per/sec, or 93 GB per/hr.
720p HDTV uncompressed
8 bit @ 1280 x 720 @ 59.94fps = 105 MB per/sec, or 370 GB per/hr.
10 bit @ 1280 x 720 @ 59.94fps = 140 MB per/sec, or 494 GB per/hr.
1080i and 1080p HDTV uncompressed
8 bit @ 1920 x 1080 @ 24fps = 95 MB per/sec, or 334 GB per/hr.
10 bit @ 1920 x 1080 @ 24fps = 127 MB per/sec, or 445 GB per/hr.
8 bit @ 1920 x 1080 @ 25fps = 99 MB per/sec, or 348 GB per/hr.
10 bit @ 1920 x 1080 @ 25fps = 132 MB per/sec, or 463 GB per/hr.
8 bit @ 1920 x 1080 @ 29.97fps = 119 MB per/sec, or 417 GB per/hr.
10 bit @ 1920 x 1080 @ 29.97fps = 158 MB per/sec, or 556 GB per/hr.
1080i and 1080p HDTV RGB (4:4:4) uncompressed
10 bit @ 1280 x 720p @ 60fps = 211 MB per/sec, or 742 GB per/hr.
10 bit @ 1920 x 1080 @ 24fps = 190 MB per/sec, or 667 GB per/hr.
10 bit @ 1920 x 1080 @ 50i = 198 MB per/sec, or 695 GB per/hr.
10 bit @ 1920 x 1080 @ 60i = 237 MB per/sec, or 834 GB per/hr.
HDMI 1.3a Specifications
According to HDMI 1.3a Spec.
Detailed timing is found in CEA-861-D or a later version of CEA-861 for the following video format timings.
Primary Video Format Timings
• 640x480p @ 59.94/60 Hz
• 1280x720p @ 59.94/60 Hz
• 1920x1080i @ 59.94/60 Hz
• 720x480p @ 59.94/60 Hz
• 720(1440)x480i @ 59.94/60 Hz
• 1280x720p @ 50 Hz
• 1920x1080i @ 50 Hz
• 720x576p @ 50 Hz
• 720(1440)x576i @ 50 Hz
Secondary Video Format Timings
• 720(1440)x240p @ 59.94/60 Hz
• 2880x480i @ 59.94/60 Hz
• 2880x240p @ 59.94/60 Hz
• 1440x480p @ 59.94/60 Hz
• 1920x1080p @ 59.94/60 Hz
• 720(1440)x288p @ 50 Hz
• 2880x576i @ 50 Hz
• 2880x288p @ 50 Hz
• 1440x576p @ 50 Hz
• 1920x1080p @ 50 Hz
• 1920x1080p @ 23.98/24 Hz
• 1920x1080p @ 25 Hz
• 1920x1080p @ 29.97/30 Hz
• 2880x480p @ 59.94/60 Hz
• 2880x576p @ 50 Hz
• 1920x1080i (1250 total) @ 50 Hz
• 720(1440)x480i @ 119.88/120 Hz
• 720x480p @ 119.88/120 Hz
• 1920x1080i @ 119.88/120 Hz
• 1280x720p @ 119.88/120 Hz
• 720(1440)x480i @ 239.76/240 Hz
• 720x480p @ 239.76/240 Hz
• 720(1440)x576i @ 100 Hz
• 720x576p @ 100 Hz
• 1920x1080i @ 100 Hz
• 1280x720p @ 100 Hz
• 720(1440)x576i @ 200 Hz
• 720X576p @ 200 Hz
Pixel Encodings and Color Depth
There are three different pixel encodings that may be sent across an HDMI cable: YCbCr 4:4:4, YCbCr 4:2:2 and RGB 4:4:4.
There are four color depths supported: 24-, 30-, 36- and 48-bits per pixel.
See also
References
- ^ Lossless Codecs Comparison ‘2007 PDF
- ^ Capturing HDMI Video: A quick guide to getting the best video from a D4 or D800 Tom Hogan
- ^ HD-SDI / HDMI digital video converters Atomos
- ^ Intensity models Blackmagic
- ^ HD-SDI Express/34 Imperx
- ^ OEM video card for 8-10-12-bit HD-SD SDI digital video to PCI Express Deltacast
- ^ Capture Card Series Magewell
- ^ DeckLink models Blackmagic
- ^ Ingex Studio - Multi-camera Tapeless Recording
- ^ The world's smallest uncompressed video recorder Blackmagic
- ^ Portable HD Field Recorder, Monitor, Playback And Playout Devices Atomos
- ^ Video Recorders Sound Devices
- ^ Video Disk Recorder KEISOKU GIKEN
External links
- Video bitrate calculator Forret
- Uncompressed Digital Video Creative Planet Network
- Uncompressed vs. Compressed Video Creative Planet Network
- Master Guide to Rigging a Nikon D800 or D800E for Video Wolfcrow