H12 Flashcards
What is a successful video standard
1) Superior performance compared to other standards
2) Should allow for innovation, only decoding process is standardized
3) Interoperability
Why standardization?
1) Interoperability
2) COTS: Can swap out with another standard encoder
3) Speed up introduction of innovative products to market
Why go to meetings?
1) Understand properties of a standard
2) Include your patented technology in a standard
3) Nudge the standard in certain directions e.g. more focus on quality instead of bandwidth.
Various stages of standardization process
Requirements > divergence > convergence > verification
What are the two current alliances?
1) MPEG: licensable compression technology (MPEG LA: pay for video encoding equipment, HEVC Advance: Pay amount for every stream that is distributed too, Independent)
2) Alliance for Open Media: Royalty free - open standards
What does a standard define?
The bitstream format and the decoding process.
What is the purpose of ITU-T codecs
In the telecommunications sector, so more focus on talking to each other. Targeting ISDN conferencing applications.
What is the purpose of ISO/IEC codecs
More in the optical drives/ storage sector. Store video on media. (-> B frames)
H.261 GOB
Picture is organized in a 6x2 matrix of GOBs. Each GOB is 176x48 px = fixed size.
Timeline of codecs
H.261 > MPEG-1 > MPEG-2/ H>262 > H.263 > MPEG-4 > H.264/AVC > H.265/HEVC > H.266/VVC
What are profiles?
Defines what tools are used in the bitstream. Main is for what they think is mostly used. e.g. Need for more features (4:4:4 chroma subsampling).
What are levels?
How much capacity the encoder/ decoder needs to have. e.g. More processing or resolutions.
How does MPEG-2 video bitstream look like?
It is packetized in a very strict manner. You need to know about the decoding process of the MPEG-2 Visual to packetize the bitstream.
What is a PB frame?
Introduced by H.263, cut MV of P frame in half and use it to predict B frame. cheap way to increase frame rate.
When is multiple reference frames introduced?
In an extension of H.263.
