in SECAM allows for a cheaper trick: division by 4 of the subcarrier frequency (and multiplication on replay). This became the standard for SECAM VHS recording in France. Most other countries kept using the same heterodyning process as for PAL or NTSC and this is known as MESECAM recording (as it was more convenient for some Middle East countries that used both PAL and SECAM broadcasts). Another difference in colour management is related to the proximity of successive tracks on the tape, which is a cause for chroma crosstalk in PAL. A cyclic sequence of 90° chroma phase shifts from one line to the next is used to overcome this problem. This is not needed in SECAM, as FM provides sufficient protection. Regarding early (analogue) videodiscs, the established Laserdisc standard supported only NTSC and PAL. However, a different optical disc format, the Thomson transmissive optical disc made a brief appearance on the market. At some point, it used a modified SECAM signal (single FM subcarrier at 3.6 MHz). The media's flexible and transmissive material allowed for direct access to both sides without flipping the disc, a concept that reappeared in multi-layered DVDs about fifteen years later. Countries and territories using PAL See also 576i PALplus Hanover bars Digital Video Broadcasting Moving image formats Prewar television stations Broadcast-safe Differential gain YUV D1 SMPTE D-2 (video) References External links Review of the different refresh rates of PAL, NTSC and motion picture films World TV standards ITU-R recommendations Television technology Television terminology Television transmission standards Video formats German inventions 1963 introductions