Abstract:
A method of storing a data file, particularly in the MPEG format and including a flow of different frames, comprises a protection system for the data file based on a parameter stored in the data file. Advantageously, the storage method comprises selectively protecting the frames by storing parameters that are associated with corresponding different frames whose values are selected to provide a playing quality level requested by an end user. Also, a method is provided for decoding a data file, particularly of the MPEG type and including a flow of different frames, wherein the data file is stored per above.
Abstract:
A process and a system is described for generating an MPEG output bitstream starting from an MPEG input bitstream. The output bitstream has a resolution modified with respect to the resolution of the input bitstream. -In the input bitstream, first portions that substantially do not affect and second portions that do affect resolution variation are distinguished. The second portions are then subjected to a function of modification of the resolution obtained by filtering the second portions in a domain of the discrete cosine transform, and then are transferred to the output bitstream. A corresponding computer program product is also provided.
Abstract:
A process for format conversion of DCT macroblocks in an MPEG video bitstream that are divided into blocks, each of which includes a plurality of microblocks. In each DCT block, the significant frequencies are identified and preserved, isolating a corresponding microblock preferably consisting of the microblock on the top left of each block and setting to zero the coefficients of the remaining microblocks. On the microblock thus isolated there is performed an inverse discrete cosine transform, and the microblock thus obtained is merged with the homologous microblocks obtained from the other blocks comprised in a respective starting macroblock, so as to give rise to a merging block. The merging block thus obtained undergoes a discrete cosine transform so as to obtain a final block, which can be assembled into a macroblock with converted format.
Abstract:
In order to generate, starting from an input MPEG bitstream, an output MPEG bitstream having at least one entity chosen among syntax, resolution, and bitrate modified with respect to the input bitstream, first portions and second portions are distinguished in the input bitstream, which respectively substantially do not affect and do affect the variation in bitrate. When at least one between the syntax and the resolution is to be modified, the first portions of the input bitstream are subjected to the required translation, then transferring said first portions subjected to syntax and/or resolution translation to the output bitstream. When the resolution is left unaltered, the second portions are transferred from the input bitstream to the output bitstream in the substantial absence of processing operations. When the resolution is changed, the second portions of the input bitstream are subjected to a filtering in the domain of the discrete cosine transform.