Uncompressed video

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Uncompressed video is digital video that either has never been compressed or was generated by decompressing previously compressed digital video. It is commonly used by video cameras, video monitors, video recording devices (including general purpose computers), and in video processors that perform functions such as image resizing, image rotation, deinterlacing, and text and graphics overlay. It is conveyed over various types of baseband digital video interfaces, such as HDMI, DVI, DisplayPort and SDI. Standards also exist for carriage of uncompressed video over computer networks.

Some HD video cameras output uncompressed video, whereas others compress the video using a lossy compression method such as MPEG or H.264. In any lossy compression process, some of the video information is removed, which creates compression artifacts and reduces the quality of the resulting decompressed video. When editing video, it is preferred to work with video that has never been compressed (or was losslessly compressed) as this maintains the best possible quality, with compression performed after completion of editing.[1]

Recording[edit]

Standalone recorders[edit]

A standalone video recorder is a device that receives uncompressed video and stores it in either uncompressed or compressed form. These devices typically have a video output which can be used to monitor or playback recorded video. When playing back compressed video, the compressed video is uncompressed by the device before being output. Such devices may also have a communication interface, such as Ethernet or USB, which can used to exchange video files with an external computer, and in some cases control the recorder from an external computer as well.

Recording to a computer[edit]

Recording to a computer is a relatively inexpensive way to implement a digital video recorder, but the computer and its video storage device (e.g., solid-state drive, RAID) must be fast enough to keep up with the high video data rate, which in some cases may be HD video or multiple video sources, or both. Due to the extreme computational and storage system performance demands of real-time video processing, other unnecessary program activity (e.g., background processes, virus scanners) and asynchronous hardware interfaces (e.g., computer networks) may be disabled, and the process priority of the recording realtime process may be increased, to avoid disruption of the recording process.

Video capture interface[edit]

HDMI, DVI and HD-SDI inputs are available as PCI Express (partly multi-channel) or ExpressCard, USB 3.0[2] and Thunderbolt interface[3][4][5] also for 2160p (4K resolution).[6][7]

Software[edit]

Software for uncompressed video is often supplied with suitable hardware or available for free: Ingex (open source).[8]

Network transmission[edit]

SMPTE 2022 is a standard for professional digital video over IP networks. The standard includes provisions for both compressed and uncompressed video formats.

Wireless interfaces such as Wireless LAN (WLAN, Wi-Fi), WiDi, and Wireless Home Digital Interface can be used to transmit uncompressed standard definition (SD) video but not HD video because the HD bit rates would exceed the network bandwidth. HD can be transmitted using higher speed interfaces such as WirelessHD and that of the Wireless Gigabit Alliance. In all cases, when video is conveyed over a network, communication disruptions or diminished bandwidth can corrupt the video or prevent its transmission.

Data rates[edit]

Uncompressed video has a constant bitrate that is based on pixel representation, image resolution, and frame rate:

data rate = color depth * vertical resolution * horizontal resolution * refresh frequency

For example:

  • 24-bit, 1080i @ 60 fps: 24 × 1920×1080 × 60/2[a] = 1.49 Gbit/s
  • 24-bit, 1080p @ 60 fps: 24 × 1920×1080 × 60 = 2.98 Gbit/s.

4:2:2 format[edit]

The data rates and storage requirements for the widely used YCbCr 4:2:2 chroma subsampling format are listed below:

NTSC
  • 8-bit, 720×480 @ 29.97 fps = 20 MB/s, or 70 GB/h
  • 10-bit, 720×480 @ 29.97 fps = 27 MB/s, or 94 GB/h
PAL
  • 8-bit, 720×576 @ 25 fps = 20 MB/s, or 70 GB/h
  • 10-bit, 720×576 @ 25 fps = 26 MB/s, or 93 GB/h
720p
  • 8-bit, 1280×720 @ 59.94 fps = 105 MB/s, or 370 GB/h
  • 10-bit, 1280×720 @ 59.94 fps = 140 MB/s, or 494 GB/h
1080i and 1080p
  • 8-bit, 1920×1080 @ 24 fps = 95 MB/s, or 334 GB/h
  • 10-bit, 1920×1080 @ 24 fps = 127 MB/s, or 445 GB/h
  • 8-bit, 1920×1080 @ 25 fps = 99 MB/s, or 348 GB/h
  • 10-bit, 1920×1080 @ 25 fps = 132 MB/s, or 463 GB/h
  • 8-bit, 1920×1080 @ 29.97 fps = 119 MB/s, or 417 GB/h
  • 10-bit, 1920×1080 @ 29.97 fps = 158 MB/s, or 556 GB/h

1080i and 1080p RGB (4:4:4)

  • 10-bit, 1280×720p @ 60 fps = 211 MB/s, or 742 GB/h
  • 10-bit, 1920×1080 @ 24 fps = 190 MB/s, or 667 GB/h
  • 10-bit, 1920×1080 @ 50i = 198 MB/s, or 695 GB/h
  • 10-bit, 1920×1080 @ 60i = 237 MB/s, or 834 GB/h

4k (3840x2160)

  • 8-bit, 3840x2160 @ 24 fps = 380 MB/s, or 1.33 TB/h
  • 8-bit, 3840x2160 @ 30 fps = 475 MB/s, or 1.67 TB/h

See also[edit]

Notes[edit]

  1. ^ Interlaced video formats transmit every other line, half the picture content, per field period. Two field are required for a full frame so the frame rate is halved in this calculation.

References[edit]

External links[edit]