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<blockquote data-quote="BarMoo" data-source="post: 122598" data-attributes="member: 175089"><p>Sorry, just caught up on the thread. Is the thread now about Analogue PAL 625 Line UHF TV RF, or, MPEG4 HDTV ?</p><p></p><p>I can understand posts about 'aliasing' in an analogue world. However, artifacts in a digital world are somewhat different.</p><p></p><p>While a 100Hz TV might need a gazillion correction toys to make a picture look bearable - that's only because the 'digital' tuner and subsequent processing is nasty and cheap. [off track] I took time out from slagging off 100Hz TV's last week to look at the latest. Wish I hadn't now.</p><p></p><p>No! the picture quality still sucks. Mind. These days the award for worst picture imaging lies firmly with LCD. I'm turning into a vynl man.</p><p></p><p>Back to the thread. The HD signal path is all digital and remains digital till it gets to your digital HD ready TV (although this is not exactly true of SKY's soon-to-be-launched HD ST<img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite6" alt=":cool:" title="Cool :cool:" loading="lazy" data-shortname=":cool:" />. In short, there shouldn't be any problems.</p><p></p><p>The most likely artifacts to occur on screen are the usual basic ones. Blocking (signal errors), Quantisation Errors (native to all compression*), Posterisation (a weird effect that <em>flattens</em> similar shades/tones or colour in a wierd way and looks very analogue) and then there's concatenation. I'm bored already. Technically, these are all artifacts and there's a whole load more. Later, perhaps.</p><p></p><p>Back in the real world, we are more likely to REALLY notice aliasing on really old shows. Two cases in point: Fawlty Towers and Yes Minister. Studio based (with 16mm inserts) recorded onto a long gone video tape format called QUAD (tape width 2") with cameras that needed the light of a thousand suns.</p><p></p><p>[Trivia] 'engineers' were known to make edits by physically slicing the tape (head rotation was near vertical and so allowed beared men to splice between the tracks).</p><p></p><p>[Not Trivia] What is clear is that shows from this era don't convert to the digital domain with dignity: psycotic attempts to compress grain from wobbly 16mm transfers and tube cameras. Moreover, the original recording system doesn't help. Perfectly OK for valve TV's of the 70's/80's, er, but not now. If your still reading this, technically, we are talking about a look on par with ITV News Channel.</p><p></p><p>My point is thus. In a digital world, these problems will establish themselves at the point of conversion: but won't, necessarily, manifest themselves within the workings of my TV. </p><p></p><p>I imagine that HD will only highlight these errors more vivaciously. Yes, anti-aliasing toys at the broadcaster end will come in very handy. Fawlty Towers on Blu-Ray HD-DVD - should be fun <img src="https://www.satellites.co.uk/styles/default/xenforo/smilies/smile.png" class="smilie" loading="lazy" alt=":)" title="Smile :)" data-shortname=":)" /> </p><p></p><p>Till then, the best TV for these old shows is a 50Hz one - and connected by RF. <strong>Not joking</strong>, its true, ask AnalogueSat.</p><p></p><p></p><p>Ramble over - Have Fun,</p><p></p><p>Mark.</p><p></p><p></p><p>*Don't know about MPEG4 or DVB-S2</p></blockquote><p></p>
[QUOTE="BarMoo, post: 122598, member: 175089"] Sorry, just caught up on the thread. Is the thread now about Analogue PAL 625 Line UHF TV RF, or, MPEG4 HDTV ? I can understand posts about 'aliasing' in an analogue world. However, artifacts in a digital world are somewhat different. While a 100Hz TV might need a gazillion correction toys to make a picture look bearable - that's only because the 'digital' tuner and subsequent processing is nasty and cheap. [off track] I took time out from slagging off 100Hz TV's last week to look at the latest. Wish I hadn't now. No! the picture quality still sucks. Mind. These days the award for worst picture imaging lies firmly with LCD. I'm turning into a vynl man. Back to the thread. The HD signal path is all digital and remains digital till it gets to your digital HD ready TV (although this is not exactly true of SKY's soon-to-be-launched HD STB). In short, there shouldn't be any problems. The most likely artifacts to occur on screen are the usual basic ones. Blocking (signal errors), Quantisation Errors (native to all compression*), Posterisation (a weird effect that [i]flattens[/i] similar shades/tones or colour in a wierd way and looks very analogue) and then there's concatenation. I'm bored already. Technically, these are all artifacts and there's a whole load more. Later, perhaps. Back in the real world, we are more likely to REALLY notice aliasing on really old shows. Two cases in point: Fawlty Towers and Yes Minister. Studio based (with 16mm inserts) recorded onto a long gone video tape format called QUAD (tape width 2") with cameras that needed the light of a thousand suns. [Trivia] 'engineers' were known to make edits by physically slicing the tape (head rotation was near vertical and so allowed beared men to splice between the tracks). [Not Trivia] What is clear is that shows from this era don't convert to the digital domain with dignity: psycotic attempts to compress grain from wobbly 16mm transfers and tube cameras. Moreover, the original recording system doesn't help. Perfectly OK for valve TV's of the 70's/80's, er, but not now. If your still reading this, technically, we are talking about a look on par with ITV News Channel. My point is thus. In a digital world, these problems will establish themselves at the point of conversion: but won't, necessarily, manifest themselves within the workings of my TV. I imagine that HD will only highlight these errors more vivaciously. Yes, anti-aliasing toys at the broadcaster end will come in very handy. Fawlty Towers on Blu-Ray HD-DVD - should be fun :) Till then, the best TV for these old shows is a 50Hz one - and connected by RF. [b]Not joking[/b], its true, ask AnalogueSat. Ramble over - Have Fun, Mark. *Don't know about MPEG4 or DVB-S2 [/QUOTE]
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