showing episodes of M*A*S*H. The first disc of MythBusters: Big Blast Collection uses this ratio, as does the Mega Movie Myths disc. Argentina It is also used on the ISDB-Tb HD service of the Argentinian public television, TV Pública, in order to adjust their old programs and 4:3 SD studio cameras to 16:9 format. Portugal The public broadcaster RTP used the 14:9 format to convert 16:9 broadcasts to the 4:3 format it still used until 2013 (for the majority of the programs broadcast). However, since 8 June 2012, they began to broadcast 16:9 material in its original aspect ratio, with the correct flag, thus ending the broadcasts featuring the 14:9 format and since January 2013, the majority of broadcasts are in 16:9 (since late 2017 downscaled from the native HD feed). Private broadcaster TVI started using the 14:9 format in August 2012 to broadcast 16:9 material instead of using 4:3 Pan & Scan, as they refused to broadcast in 16:9. However, on 3 October 2015, it began to broadcast in full widescreen. Turkey From 2005 to 2011, TRT broadcast (except TRT HD) Eurovision Song Contest by cropping to 14:9. Many channels of TRT were broadcasting 4:3 at the time; narrow black bars are added to the top and bottom. Mathematics The aspect ratio of 14:9 (1.555...) is the arithmetic mean (average) of 16:9 and 4:3 (12:9), . More practically, it is approximately the geometric mean (the precise geometric mean is ), and in this sense is mathematically a compromise between these two aspect ratios: two equal area pictures (at 16:9 and 4:3) will intersect in a box with aspect ratio the geometric mean, as demonstrated in the image at top (14:9 is just slightly wider than the intersection). In this way 14:9 balances the needs of both 16:9 and 4:3, cropping or distorting both about equally. Similar considerations were used in the choice of 16:9 by the SMPTE, which balanced 2.35:1 and 4:3. See also Shoot and protect Pillarbox References Picture aspect ratios it:Aspect ratio (immagine)#Il 14:9