VideoHelp Forum
+ Reply to Thread
Results 1 to 2 of 2
Thread
  1. Член BJ_M's Avatar
    Join Date: Jul 2002
    Location: Canada
    Search Comp PM
    Scalability offers a set of tools by which video can be coded at different Resolutions (different scales) in one total bitstream.
    On the decoder side, video can be decoded at the suitable resolution (scale) extracting a portion of the total bitstream.
    It adds compatibility and error concealment.

    Types of Scalability
    Quality (SNR)
    The SNR scalability allows the enhancement of the video quality by means of an enhancement layer bitstream. The DCT coefficients encoded by an another layer are refined between the inverse quantisation and the inverse DCT processes. See also the block layer.
    So two different goals are obtained: compatibility, as the base layer bitstream can be decoded by a simpler decoder, and graceful degradation, as the base layer can be better protected in transmission with errors.
    Spatial
    The spatial scalability allows the increasing of the picture size. The enhancement layer bitstream refers to the lower layer bitstream in order to get a possible spatial prediction for the macroblock. The spatial prediction is made from the lower layer decoded picture referenced by the lower layer temporal reference, that picture needs to be upsampled to the enhancement layer picture size. In the enhancement layer, prediction can be: only temporal, only spatial or a weighted combination of both. Spatial prediction may be used also in Intra pictures.
    The base layer bitstream can be decoded by simpler decoders, while the more complex ones may have larger displays. Error concealment is possible protecting better the lower bitstream during transmission and displaying the upconverted images.
    Temporal
    The temporal scalability allows an ehancement of the picture rate. It hasn't been included yet as a tool of a defined Profile.
    Frequency (Data Partitioning)
    Frequency scalabilty provides an ehancement in terms of "bands" of DCT coefficients. The upper layer would contain those DCT coefficients that have been set to zero in the lower layer stream. It hasn't been included yet as a tool of a defined Profile
    Quote Quote  
  2. Banned
    Join Date: Dec 2011
    Location: way East Europe (WEE)
    Search Comp PM
    You missed the 4D-noise reductio capability nd made a mistake . I don`t think its from translating....

    Don`t confuse '''4D noise reduction''' with SNR. Don`t confuse it with scalability and enhancement with the coefficient`s . Scalability is the capability of an image (truly device) to fit an area for rendering . For people who ... scalability fits down to a smaller screensize, or up to a bigger screen and then it`s a thing called upscalling .


    Allow me a small correction SNR is not an enhancement but a coefficient especially used in analog2video mettering. When you get a video signal interferred in a device or in transmission line by an em field than has an electric effect on receptor, you consider SNR.


    By research you get a coeff. which is SNR and allows a quality coeficient of colour contents to an acceptable level . In a catalog from akai you can encounter low SNR:<45dB for video VHS devices . This coefficient are trade secrets and a sort of secrets at SONYs .
    Last edited by ledishis; 12th Dec 2011 at 15:23.
    Quote Quote