This codec (unlike many others) defines a direct way to scale DC/AC coefficients using quantization parameter instead of specifying quantization matrixes. Quantization is the compression step that potentially loses the most information in a lossy compression scheme such as VC-1. VC-1 has 13 different zigzag patterns depending on various parameters (block size, interlacing, prediction mode and intra/inter).
Unlike many codec standards preceding VC-1, the specification defines a bit-accurate transform method that all implementations are expected to conform to so as to minimize transform error.Īfter tranforming sample data into the transform domain, VC-1 reorders the transformed data in a zigzag pattern which makes certain successive coding techniques more effective.
#Vc1 codec droid full
The transform may operate on the full 8x8 block or any of the 3 supported sub-block sizes (8x4, 4x8, or 4x4). VC-1 uses a variation of the Discrete Cosine Transform to convert blocks of samples into a transform domain to facilitate more efficient coding. Further, the coding method may divide an individual 8x8 block into 2 8x4 blocks, 2 4x8 blocks, or 4 4x4 blocks. Each 16x16 macroblock is comprised of 6 8x8 sample blocks (4 Y blocks, 1 U block, and 1 V block). When VC-1 codes an image, it divides the image into macroblocks. VC-1 codes a sequence of images in the YUV 4:2:0 colorspace. Representative Resolutions by Frame Rate (Format) The combinations of profiles and levels represent trade-offs between encoding/decoding complexity, compression quality, and compressed image size. VC-1 has 3 profiles: simple, main, and advanced. VC-1 video will probably be encapsulated in other types of containers and stream formats such as MPEG for HD-DVD transport.
#Vc1 codec droid windows
Note that the FourCC 'WMV9' may not actually exist in the wild but the acronym gained prominence anyway due to the fact that this video codec was introduced as part of the Windows Media 9 tool suite. Most commonly, VC-1 data is found inside of Microsoft ASF files and identified with the FourCC 'WMV3' for VC-1 simple and main profile and FourCC 'WVC1' for advanced profile. 3.2 Macroblocks, Blocks, and Sub-blocks.