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Dirac (video compression format)
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Dirac (video compression format)
Dirac (and Dirac Pro, a subset standardised as SMPTE VC-2) is an open and royalty-free video compression format, specification and software video codec developed by BBC Research & Development. Dirac aimed to provide high-quality video compression for Ultra HDTV and competed with existing formats such as H.264.
The specification was finalised in January 2008, and further developments were only bug fixes and constraints. In September of that year, version 1.0.0 of an I-frame only subset known as Dirac Pro was released and was standardised by the SMPTE as VC-2. Version 2.2.3 of the full Dirac specification, including motion compensation and inter-frame coding, was issued a few days later. Dirac Pro was used internally by the BBC to transmit HDTV pictures at the Beijing Olympics in 2008.
Two open source and royalty-free video codec software implementations, libschrodinger and dirac-research, were developed. The format implementations were named in honour of the theoretical physicists Paul Dirac and Erwin Schrödinger, who shared the 1933 Nobel Prize in Physics.
Dirac supports resolutions of HDTV (1920×1080) and greater, and is claimed to provide significant savings in data rate and improvements in quality over video compression formats such as MPEG-2 Part 2, MPEG-4 Part 2 and its competitors such as Theora and WMV. Dirac's implementers made a preliminary claim of "a two-fold reduction in bit rate over MPEG-2 for high definition video", which makes it comparable to VC-1 and simpler profiles of H.264.
Dirac supports both constant bit rate and variable bit rate operation. When the low delay syntax is used, the bit rate will be constant for each area (Dirac slice) in a picture to ensure constant latency. Dirac supports lossy and lossless compression modes.
Dirac employs wavelet compression, like the JPEG 2000 and PGF image formats and the Cineform professional video codec, instead of the discrete cosine transforms used in MPEG compression formats. Two of the specific wavelets Dirac can use are nearly identical to JPEG 2000's (known as the 5/3 and 9/7 wavelets), as well as two more derived from them.
Dirac can be used in Ogg and Matroska container formats and is also registered for use in the ISO base media (MP4) file format and MPEG transport streams.
The BBC does not own any patents on Dirac. They previously had some patent applications with plans to irrevocably grant a royalty-free licence for their Dirac-related patents to everyone, but they let the applications lapse. In addition, the developers have said they will try to ensure that Dirac does not infringe on any third party patents, enabling the public to use Dirac for any purpose.
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Dirac (video compression format)
Dirac (and Dirac Pro, a subset standardised as SMPTE VC-2) is an open and royalty-free video compression format, specification and software video codec developed by BBC Research & Development. Dirac aimed to provide high-quality video compression for Ultra HDTV and competed with existing formats such as H.264.
The specification was finalised in January 2008, and further developments were only bug fixes and constraints. In September of that year, version 1.0.0 of an I-frame only subset known as Dirac Pro was released and was standardised by the SMPTE as VC-2. Version 2.2.3 of the full Dirac specification, including motion compensation and inter-frame coding, was issued a few days later. Dirac Pro was used internally by the BBC to transmit HDTV pictures at the Beijing Olympics in 2008.
Two open source and royalty-free video codec software implementations, libschrodinger and dirac-research, were developed. The format implementations were named in honour of the theoretical physicists Paul Dirac and Erwin Schrödinger, who shared the 1933 Nobel Prize in Physics.
Dirac supports resolutions of HDTV (1920×1080) and greater, and is claimed to provide significant savings in data rate and improvements in quality over video compression formats such as MPEG-2 Part 2, MPEG-4 Part 2 and its competitors such as Theora and WMV. Dirac's implementers made a preliminary claim of "a two-fold reduction in bit rate over MPEG-2 for high definition video", which makes it comparable to VC-1 and simpler profiles of H.264.
Dirac supports both constant bit rate and variable bit rate operation. When the low delay syntax is used, the bit rate will be constant for each area (Dirac slice) in a picture to ensure constant latency. Dirac supports lossy and lossless compression modes.
Dirac employs wavelet compression, like the JPEG 2000 and PGF image formats and the Cineform professional video codec, instead of the discrete cosine transforms used in MPEG compression formats. Two of the specific wavelets Dirac can use are nearly identical to JPEG 2000's (known as the 5/3 and 9/7 wavelets), as well as two more derived from them.
Dirac can be used in Ogg and Matroska container formats and is also registered for use in the ISO base media (MP4) file format and MPEG transport streams.
The BBC does not own any patents on Dirac. They previously had some patent applications with plans to irrevocably grant a royalty-free licence for their Dirac-related patents to everyone, but they let the applications lapse. In addition, the developers have said they will try to ensure that Dirac does not infringe on any third party patents, enabling the public to use Dirac for any purpose.