Digital video - Analogue audio
- Thread starter alindsay
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sergeauckland
pfm Member
Possibly you're missing that digital audio only seems shunned on certain Fora and in certain parts of the HiFi press. The general public and music business have been happy with digital audio since the 1980s.
S.
S.
Pete the Feet
pfm Member
Surely analogue video must be better. Buffy the Vampire Slayer in digital loses that dreamy ethereal quality that analogue and only analogue alone can provide. Our eyes are not digital etc.
Sent from my mobile, excuse all typos
Sent from my mobile, excuse all typos
sergeauckland
pfm Member
Analogue video would have been fine until colour came along. In order to keep backwards compatibility with black and white receivers, and to use existing transmitters, colour had to be added to a B&W picture in a way that made it compatible, much like stereo was added to the FM signal leaving the mono to be received as normal.
In the PAL or NTSC systems, colour information modulates a subcarrier (3.8Mhz or NTSC, 4.43 MHz for PAL, which then is added to the normal mono picture. In a mono receiver, the extra information just adds a bit of noise, but a colour reciever detects the subcarrier, and demodulates the colour information. The problem is that whilst the B&W part (the luminance information) is a full resolution, the colour (the Chrominance information) is at low resolution, and the receivers can't fully descriminate between fine detail n the luma, with colour changes in the chroma, hence the colour patterning on clothes with fine patterns. Sharp edges with colour changes are also rendered fuzzy as the limited chroma bandwidth limits how quickly the colour can change.
All in all, analogue colour TV is a bodge, but one that worked, in part because the displays of the time didn't have sufficient resolution to show up too many artefacts, and because our colour vision isn't as acute as our B&W vision.
Digital TV, however, allowed the chroma and luma information to be carried seperately, however, in order to get it into a broadcast channel's bandwidth, it had to be compressed, and that created a new set of artefacts, mostly to do with motion rather than colour. The bit-reduction works very well with reasonably static shots, Newsreaders for example are far better displayed in digital TV than analogue, but fast-moving random images, like rippling water, or fire and smoke result in blocky displays where the bit reduction algorithms run out of bits.
So neither is perfect, it's almost a case of choose your artefact, but in gerneral, and with a modern Hi resolution display, analogue TV would become almost unwatchable due to the colour and edge artefact whilst digital TV is much better in that respect, with limitations on motion.
S.
Arfa
pfm Member
Well prior to the analogue TV turn off, with a good signal analogue TV channels often looked better than the digital ones. The latter tend to be overlay compressed and macro block badly when there's large amount of movement on screen. e.g. water, smoke, fire shots etc.
That said, digital video is fine, its the compression that's employed that can make it look shit. Same as audio I suppose, crappy bitrate mp3s will sound bad, whereas lossless 24/96 flac can sound lovely. You just rarely see lossless video compression, let along uncompressed, outside of professional setups, purely down to the sheer amount of data that needs throwing around. A 3:30 standard def music video saved as a MOV in uncompressed YUV422 format comes in at around 3GB! You ain't going to be streaming that off your Wireless NAS, you'll need a pretty poky wired network and some beefy hard drives (preferably in a striped raid).
That said, digital video is fine, its the compression that's employed that can make it look shit. Same as audio I suppose, crappy bitrate mp3s will sound bad, whereas lossless 24/96 flac can sound lovely. You just rarely see lossless video compression, let along uncompressed, outside of professional setups, purely down to the sheer amount of data that needs throwing around. A 3:30 standard def music video saved as a MOV in uncompressed YUV422 format comes in at around 3GB! You ain't going to be streaming that off your Wireless NAS, you'll need a pretty poky wired network and some beefy hard drives (preferably in a striped raid).
Werner
pfm Member
Make it YUV444. 422 already has thrown out half of the chroma information.
Pete the Feet
pfm Member
Serg Is that why football matches can look juddery or is it also partially to do with the type of the newer flat screen tvs
Sent from my mobile, excuse all typos
Sent from my mobile, excuse all typos
sonddek
Trade: SUPATRAC
Actually, to be fair, the best movie reproduction I have ever seen was the Final Cut of Blade Runner, which was a very high rez re-digitisation of the original film stock. I think it illustrates that the problems people report with digital often come down to sample-rate and bit depth. There's nothing intrinsically wrong with digital, but sometimes specific formats fail to exceed analogue formats they replace. As a photographer I have seen this happen with pro cameras, where digital cameras often replaced film before they provided better quality, because they have other advantages. As time has marched on, digital cameras have improved hand over fist, to the extent that 35mm format digital cameras now approach the quality of medium format film.
Pete the Feet
pfm Member
It makes you think with all this analogue to digital and the previous format variations from 4:3, 16:9, 2.35:1. The display format caused us real problems when we bought our first DVD player as the TV couldn't cope, it was like watching a film through a letterbox. As we haven't watched TV programmes for many a year it didn't present a problem, but I remember seeing other peoples widescreen TVs and everything looked squished.
It seems like 2 steps forward and 3 steps back. I suppose it will all be an overall improvement over analogue eventually.
It seems like 2 steps forward and 3 steps back. I suppose it will all be an overall improvement over analogue eventually.
sergeauckland
pfm Member
Yes, sports with fast moving shots, especially panning shots, create a huge amount of data which the compression algorythms just can't cope with. Hence juddery motion and blocky presentation. Rippling water is about the worst possible signal as it's almost completely random, with little correlation between adjacent sections. A moving background, behind, say, a Formula 1 car will also cerate a lot of data which the compressor can't cope with. Long shots of football, on the other hand, can be quite sharp, as there's not a lot of detail in the field, cricket likewise.
Most of it is due to the transmission, but some is due to the display, for example, colour finging in out-of-focus areas of colour is more the display.
S.