All posts by Briantist
Below are all of Briantist's postings, with the most recent are at the bottom of the page.
Mark A.: And NICAM of course... 3 days of analogue to go - goodbye to NICAM 728 | ukfree.tv - 10 years of independent, free digital TV advice .
| link to this comment |
Richard Davis: Yes, indeed, NICAM was used by the BBC to put digital audio down "analogue vision circuits".
I can confirm to you that NICAM was removed from internal over a decade ago. It was replaced by more efficient codecs.
| link to this comment |
Richard Davis: The stereo system used on video cassettes isn't NICAM, it is an analogue system. It was very rare to find VCRs that decoded NICAM and recorded this as "analogue stereo" in domestic equipment.
See VHS - Wikipedia, the free encyclopedia .
Of course, most VCRs output the mono recording on both the left and right outputs (SCART and/or RCA), so it would have not been obvious you were listening to the mono.
| link to this comment |
Insider: It's not. FM is no longer distributed that way, it was superseded the best part of 15 years ago.
It's just not needed as both vision and sound are carried on the SDH - see http://en.wikipedia.org/w…rchy .
| link to this comment |
trevorjharris: as well as 4Tel on channel 4 and telesoftware on Ceefax.
All those hidden pages with hexadecimal digits A to F in them...
| link to this comment |
It's also interesting to note that there are 360 bits per line in the teletext broadcast.
Which is, of course, half of the 720 samples per line in the "main profile at main level" in MPEG-2 for "625-line television", or 576i.
This (sort of) equates to a "forward error correction" of 1/2.
Only 576 lines of the 625 lines are used for the picture, which is why other 49 could be used for teletext services.
Note also that teletext is in "in band" service, carried as part of the picture, and not an "out band" service like NICAM which is carried on a different carrier.
| link to this comment |
Another interesting feature of the "fast text" service that uses the coloured buttons in teletext is the use of Hamming Coding - Hamming(7,4) - Wikipedia, the free encyclopedia .
| link to this comment |
More at .. BBC's Ceefax: the last pixel show | Media Monkey | Media | guardian.co.uk ..
| link to this comment |
Sunday 21 October 2012 10:45AM
Just to add, it will be Freeview 45 in Scotland too, as BBC Alba is on Freeview 8.