Patent ID: 7369613
Filing Date: 2008-05-06
Classification: H04N

Abstract:
1. A process for converting the format of MPEG video bitstreams, comprising: identifying DCT macroblocks in said bitstreams, each macroblock comprising a plurality of blocks; dividing each of said DCT macroblocks into respective DCT blocks, each block in turn comprising a plurality of microblocks; identifying and preserving, in each DCT block comprised in a DCT macroblock, the significant frequencies, isolating a corresponding microblock of said DCT block; performing an inverse discrete cosine transform on the isolated microblock; gathering said microblock, which has been isolated and subjected to an inverse discrete cosine transform, together with the homologous microblocks obtained from the other DCT blocks comprised in a respective macroblock, so as to obtain a merging block; and applying to said merging block the discrete cosine transform so as to obtain a final block that can be assembled into a macroblock with converted format; wherein said operations of performing on the isolated DCT microblock an inverse cosine discrete transform, gathering said DCT microblock, which has been isolated and subjected to an inverse discrete cosine transform, with the homologous microblocks obtained from the other DCT blocks comprised in a respective DCT macroblock, and applying to said merging block the discrete cosine transform are carried out by multiplying said isolated microblock and said homologous DCT microblocks by respective multiplication matrices on the left and on the right, according to the position of the DCT block, so as to obtain respective temporary blocks and adding together said respective temporary blocks, the sum of said temporary blocks identifying said final block that can be assembled into a macroblock with converted format.