IMPROVED DECODING OF A VIDEO SIGNAL FROM A VCR
Publication Date: 2002-Sep-24
The IP.com Prior Art Database
In order to superimpose (as a window on a main screen) a video sequence received by a display, this video sequence (CVBS) is decoded (converted into digital) and stored in a memory (DMA). The main screen is for instance an Internet navigator. When the video sequence is coming from a VCR in fast-forward mode, a given number of lines (depending on the fast-forward speed) is missing in every field (see below table). Precisely, the number of lines N per picture depending on the fast-forward speed is given by the formula : N = 625 . [ 1 – (n-1).0.24.k/100 ] where n is the speed multiplication factor. The decoding process for a field starts on the vertical synchronization pulse and awaits a standard number of lines. If some are missing, it keeps looking for them and consequently misses the following vertical synchronization pulse. This results in a jerky display. The inventors propose to measure the time length between two vertical synchronization pulses, to deduce the playing speed of the VCR and to control accordingly the number of lines to be decoded by the decoding process. The remaining lines can be forced to black. The window insertion of the fast-forward sequence from the VCR occurs without problem.