Intra-frame
Encyclopedia
Intra-frame coding is used in video coding (compression). It is part of group of pictures
with inter frame
s.
The term intra-frame coding refers to the fact that the various lossless and lossy compression techniques are performed relative to information that is contained only within the current frame, and not relative to any other frame in the video sequence. In other words, no temporal processing is performed outside of the current picture or frame. Non-intra coding techniques are extensions to these basics. It turns out that this block diagram is very similar to that of a JPEG still image video encoder, with only slight implementation detail differences.
Inter frame has been specified by the CCITT in 1988-1990 by H.261
for the first time. H.261 was meant for teleconferencing and ISDN telephoning.
data format (often wrongly marked as YUV
, which should be used for analog data only). The coding process varies greatly depending on which encoder is used (e.g.: JPEG
, H.264
), but the most common steps usually include: partitioning into macroblock
s, transform (e.g.: DCT
, or wavelet
), quantization
and entropy encoding
.
Intra-frame coding is applied to the partitioning into macroblocks step.
Group of pictures
In Video coding, a group of pictures, or GOP structure, specifies the order in which intra- and inter-frames are arranged. The GOP is a group of successive pictures within a coded video stream. Each coded video stream consists of successive GOPs...
with inter frame
Inter frame
An inter frame is a frame in a video compression stream which is expressed in terms of one or more neighboring frames. The "inter" part of the term refers to the use of Inter frame prediction...
s.
The term intra-frame coding refers to the fact that the various lossless and lossy compression techniques are performed relative to information that is contained only within the current frame, and not relative to any other frame in the video sequence. In other words, no temporal processing is performed outside of the current picture or frame. Non-intra coding techniques are extensions to these basics. It turns out that this block diagram is very similar to that of a JPEG still image video encoder, with only slight implementation detail differences.
Inter frame has been specified by the CCITT in 1988-1990 by H.261
H.261
H.261 is a ITU-T video coding standard, ratified in November 1988. It is the first member of the H.26x family of video coding standards in the domain of the ITU-T Video Coding Experts Group , and was the first video codec that was useful in practical terms.H.261 was originally designed for...
for the first time. H.261 was meant for teleconferencing and ISDN telephoning.
Coding process
Data is usually read from a video camera or a video card in the YCbCrYCbCr
YCbCr or Y′CbCr, sometimes written or , is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. Y′ is the luma component and CB and CR are the blue-difference and red-difference chroma components...
data format (often wrongly marked as YUV
YUV
YUV is a color space typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, thereby typically enabling transmission errors or compression artifacts to be more efficiently...
, which should be used for analog data only). The coding process varies greatly depending on which encoder is used (e.g.: JPEG
JPEG
In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....
, H.264
H.264/MPEG-4 AVC
H.264/MPEG-4 Part 10 or AVC is a standard for video compression, and is currently one of the most commonly used formats for the recording, compression, and distribution of high definition video...
), but the most common steps usually include: partitioning into macroblock
Macroblock
Macroblock is an image compression component and technique based on discrete cosine transform used on still images and video frames. Macroblocks are usually composed of two or more blocks of pixels. In the JPEG standard macroblocks are called MCU blocks....
s, transform (e.g.: DCT
Discrete cosine transform
A discrete cosine transform expresses a sequence of finitely many data points in terms of a sum of cosine functions oscillating at different frequencies. DCTs are important to numerous applications in science and engineering, from lossy compression of audio and images A discrete cosine transform...
, or wavelet
Discrete wavelet transform
In numerical analysis and functional analysis, a discrete wavelet transform is any wavelet transform for which the wavelets are discretely sampled...
), quantization
Quantization (image processing)
Quantization, involved in image processing, is a lossy compression technique achieved by compressing a range of values to a single quantum value. When the number of discrete symbols in a given stream is reduced, the stream becomes more compressible. For example, reducing the number of colors...
and entropy encoding
Entropy encoding
In information theory an entropy encoding is a lossless data compression scheme that is independent of the specific characteristics of the medium....
.
Intra-frame coding is applied to the partitioning into macroblocks step.