Intra-frame coding: Difference between revisions
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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. This mode will be described first because it is simpler, and because non-intra coding techniques are extensions to these basics. Figure 1 shows a block diagram of a basic video encoder for intra frames only. 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. |
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. This mode will be described first because it is simpler, and because non-intra coding techniques are extensions to these basics. Figure 1 shows a block diagram of a basic video encoder for intra frames only. 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. |
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Inter frame has been specified by the CCITT in 1988-1990by in H.261 by the first time. H.261 was meant for teleconferencing and ISDN telephoning. |
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== Coding of process == |
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Data are usually read from videocamera or videocard as YCbCr data format (often wrong marked as YUV that should be used for analog data only). YUV data is partitioned into [[Macroblocks|macroblock]] of 8x8 (...) pixels. Each macroblock is transformed with [[Cosine discrete transform|CDT]] then quantised, ZIG-ZAG, RLE, Huffman --> 100101001. |
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== See also == |
== See also == |
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Revision as of 08:51, 23 December 2006
Inter-frame (P-frame) Coding is used in video coding (compression). It is part of Group of Pictures with Inter-frame.
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. This mode will be described first because it is simpler, and because non-intra coding techniques are extensions to these basics. Figure 1 shows a block diagram of a basic video encoder for intra frames only. 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 1988-1990by in H.261 by the first time. H.261 was meant for teleconferencing and ISDN telephoning.
Coding of process
Data are usually read from videocamera or videocard as YCbCr data format (often wrong marked as YUV that should be used for analog data only). YUV data is partitioned into macroblock of 8x8 (...) pixels. Each macroblock is transformed with CDT then quantised, ZIG-ZAG, RLE, Huffman --> 100101001.