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S-Video vs Composite Question
I just signed up for Comcast cable a couple of weeks ago and am
sending the signal, from the Motorola 6412 Digital Comcast Receiver, to a standalone Philips Tivo. After checking and double checking, it seems to me that I'm getting a better picture, from the Tivo to TV, on composite video than on S-Video. Is that normal? I always thought the picture quality would be better on S-Video. |
S-Video vs Composite Question
Definitely not normal. Resolution, contrast and color should all be clearly
improved on SVHS. Replace the cable first. wrote in message ... I just signed up for Comcast cable a couple of weeks ago and am sending the signal, from the Motorola 6412 Digital Comcast Receiver, to a standalone Philips Tivo. After checking and double checking, it seems to me that I'm getting a better picture, from the Tivo to TV, on composite video than on S-Video. Is that normal? I always thought the picture quality would be better on S-Video. |
S-Video vs Composite Question
wrote in message
... I just signed up for Comcast cable a couple of weeks ago and am sending the signal, from the Motorola 6412 Digital Comcast Receiver, to a standalone Philips Tivo. After checking and double checking, it seems to me that I'm getting a better picture, from the Tivo to TV, on composite video than on S-Video. Is that normal? I always thought the picture quality would be better on S-Video. I've seen this sometimes, it depends on the particular equipment. |
S-Video vs Composite Question
wrote in message ... I just signed up for Comcast cable a couple of weeks ago and am sending the signal, from the Motorola 6412 Digital Comcast Receiver, to a standalone Philips Tivo. After checking and double checking, it seems to me that I'm getting a better picture, from the Tivo to TV, on composite video than on S-Video. Is that normal? I always thought the picture quality would be better on S-Video. Resolution, contrast and color are not significantly improved with an S-Video interconnect. On an analog NTSC set equipped with a low quality filter to separate the brightness from the color signal, S-Video interconnects will avoid the need for the filter since the color and brightness is not mixed to begin with. With a composite interconnect and a poor filter you will see artifacts. Typically, moving worm like artifacts on bright vertical lines. This is not an issue with S-Video interconnects or on sets with a decent filter. On most decent sets you will see little difference. Richard. |
S-Video vs Composite Question
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S-Video vs Composite Question
Good analysis, Alan.
My goal was to determine the best quality video source to the Tivo so that I could record and store movies on large hard drives. I have the newer version of the 6412, the Phase III, which has the HDMI output, and has a much better analog tuner than the 5100 I just replaced. However, I seldom view the analog channels. I have the 6412 connected to a 30 inch Philips HDTV, with Component cables, and get excellent HD and SD quality. The Composite or S-Video is connected to the Tivo, which is connected to a 26 inch Samsung HDTV for monitoring the Tivo. I've tried several different S-Video cables, but results is the same. Thanks to all for helpful suggestions. On Sun, 12 Mar 2006 19:42:54 GMT, Alan Bealby wrote: On Sun, 12 Mar 2006 05:30:59 -0600, wrote: I just signed up for Comcast cable a couple of weeks ago and am sending the signal, from the Motorola 6412 Digital Comcast Receiver, to a standalone Philips Tivo. After checking and double checking, it seems to me that I'm getting a better picture, from the Tivo to TV, on composite video than on S-Video. Is that normal? I always thought the picture quality would be better on S-Video. It is a fairly common misconception that a S-Video connection will always give a better video signal than a composite video connection. Given an equivalent quality video source, then it is usually true that the quality of the video signal passed will improve as one goes from composite video , to S-Video, to component video to digital video ( DVI or HDMI). However, this order may change depending on the length and quality of the particular video cable and in some cases it will be very hard to notice any difference. The other reason the generalization is not necessarily true is that the quality of the source is not always the same. In particular, cable boxes often have a problem with analog cable channels. The S-Video, component video and digital video outputs of a cable box require processing of the analog video signal which would otherwise be done in the TV or, in your case, by the Tivo. Cable boxes have been notorious for their poor processing of the analog video channels and, in a lot of cases, it is better to have the necessary processing of these signals done in devices with better quality processing such as the better quality TVs or recorders. This will depend very much on what devices you have, their video processing capabilities and the type of video connection you use. Another factor in this equation is that analog TV displayed on large screen TV's from the same distance that one would view a smaller TV means that the large screen will show imperfections in the TV picture quality more than a smaller screen does. Your cable box is for HD pictures so if you have a large screen TV then you will be bothered more by the poorer inherent quality of Standard Definition TV exasperated by noise introduced by the poor video processing in the 6412 cable box. Note there are reports that the newer model 6412 cable box with the HDMI output has better processing of the analog channels so this problem is eliminated or less significant for those cable boxes. Unfortunately, you really have to try the particular combinations you have available to see which connection has the least problem. There is also the ease of use factor to consider. I have my 6412 cable box connected with component video and composite video. I use the component video for SD and HD digital channels and composite video for analog cable channels. This gives me the best video quality. However it is a nuisance to change the video source on my TV so I often will not bother to switch video sources when changing to a analog channel from a digital channel unless it starts to bother me too much or unless I know I going to stay on an analog channel for a long time. Alan Bealby Remove no_spam from my E-Mail address |
S-Video vs Composite Question
This is a common misconception. Actually, it is very typical. S-VHS
connections are often a poor choice. S-VHS connections were designed for signals where the luma and chroma are encoded discretely. Signals from cable, sat, and DVD sources do not get video in the form of luma and chroma. These units have to filter the signal to separate them to output at the s-video ports. Typically, the filters are quite crude compared to those in the television and do a poorer job. The specifics of processing are quite variable with equipment. I would recommend trying both s and composite connections to see which is better. When using VHS units which record the luma and chroma discretely there will likely be an improvement. With the previsously mentioned sources, it depends, but the set will usually have the better filtering. Leonard "Dan G" wrote in message ... Definitely not normal. Resolution, contrast and color should all be clearly improved on SVHS. Replace the cable first. wrote in message ... I just signed up for Comcast cable a couple of weeks ago and am sending the signal, from the Motorola 6412 Digital Comcast Receiver, to a standalone Philips Tivo. After checking and double checking, it seems to me that I'm getting a better picture, from the Tivo to TV, on composite video than on S-Video. Is that normal? I always thought the picture quality would be better on S-Video. |
S-Video vs Composite Question
Leonard Caillouet wrote:
This is a common misconception. Actually, it is very typical. S-VHS connections are often a poor choice. S-VHS connections were designed for signals where the luma and chroma are encoded discretely. Signals from cable, sat, and DVD sources do not get video in the form of luma and chroma. These units have to filter the signal to separate them to output at the s-video ports. Typically, the filters are quite crude compared to those in the television and do a poorer job. The specifics of processing are quite variable with equipment. I would recommend trying both s and composite connections to see which is better. When using VHS units which record the luma and chroma discretely there will likely be an improvement. With the previsously mentioned sources, it depends, but the set will usually have the better filtering. Leonard That's very interesting Leonard and I suppose it makes sense. You are saying that the luma and chroma must be separated at some point before the image is displayed by the TV monitor. And you are saying that a cable , sat or DVD source does not contain this discreet luma / chroma information and the unit must create this signal to output it at the S output connector. And I think you are saying that if you use composite out of cable, sat or DVD and let the TV do the luma / chroma separating that the end result is the same and that any differences depend on the quality of the circuit that does this filtering. Be it the cable, sat, DVD player or the TV. I am aware that SVHS recorders do record this luma / chroma separately so there would be an advantage to using S out of those devices. I'm confused about DVD players though. Do they not contain luma / chroma signals in the form of R-Y, B-Y, Y? Would it not be better to derive the luma / chroma from that component signal instead of from a composite video signal? Or am I wrong about the actual encoded data on a DVD? A little off the main topic but I've had experience with cheap-o Radio Shack devices that convert composite to S. They are nothing more than a capacitor and resistor. I'm wondering if anyone makes high quality devices that do this trick. You'd think there might be a good after market demand for something like this. The thinking would be... don't let your cable box or TV do this necessary job... let our SuperS Gadget to it. |
S-Video vs Composite Question
"DanR" wrote in message et... Leonard Caillouet wrote: This is a common misconception. Actually, it is very typical. S-VHS connections are often a poor choice. S-VHS connections were designed for signals where the luma and chroma are encoded discretely. Signals from cable, sat, and DVD sources do not get video in the form of luma and chroma. These units have to filter the signal to separate them to output at the s-video ports. Typically, the filters are quite crude compared to those in the television and do a poorer job. The specifics of processing are quite variable with equipment. I would recommend trying both s and composite connections to see which is better. When using VHS units which record the luma and chroma discretely there will likely be an improvement. With the previsously mentioned sources, it depends, but the set will usually have the better filtering. Leonard That's very interesting Leonard and I suppose it makes sense. You are saying that the luma and chroma must be separated at some point before the image is displayed by the TV monitor. And you are saying that a cable , sat or DVD source does not contain this discreet luma / chroma information and the unit must create this signal to output it at the S output connector. And I think you are saying that if you use composite out of cable, sat or DVD and let the TV do the luma / chroma separating that the end result is the same and that any differences depend on the quality of the circuit that does this filtering. Be it the cable, sat, DVD player or the TV. I am aware that SVHS recorders do record this luma / chroma separately so there would be an advantage to using S out of those devices. I'm confused about DVD players though. Do they not contain luma / chroma signals in the form of R-Y, B-Y, Y? Would it not be better to derive the luma / chroma from that component signal instead of from a composite video signal? Or am I wrong about the actual encoded data on a DVD? A little off the main topic but I've had experience with cheap-o Radio Shack devices that convert composite to S. They are nothing more than a capacitor and resistor. I'm wondering if anyone makes high quality devices that do this trick. You'd think there might be a good after market demand for something like this. The thinking would be... don't let your cable box or TV do this necessary job... let our SuperS Gadget to it. Your understanding is greater than I expected and I very much oversimplified. All MPEG compressed video is encoded as YUV. While it is true that the conversion to YIQ may preserve much information that can be lost in the conversion to composite and the subsequent filtering to separate luma and chroma, many systems seem to do a lousy job of the conversion and likely just SAW filter it after it is converted to composite. In this case, the (usually) much more elaborate comb filter in the television will do a better job. I actually traced the signals in a SA cable converter recently and this appears to be exactly what it was doing. Why would they do this instead of taking the wider bandwidth earlier in the conversion? My guess is that they are perfectly happy to limit the bandwidth of the chroma and luma to minimize complaints about noisy signals. The bottom line is that you just have to try it. Some DVD players do a much better job than cable and sat boxes, but some look better with composite connections. As so often is the case, it depends, and one should never underestimate the ability of manufacturers to screw things up. The simple passive filter that you described is a very crude conversion but will usually work, just not very well. Some outboard scalers likely have pretty good conversion to s-video, but I never paid much attention to it. Leonard |
S-Video vs Composite Question
Alan Bealby wrote:
On Sun, 12 Mar 2006 05:30:59 -0600, wrote: I just signed up for Comcast cable a couple of weeks ago and am sending the signal, from the Motorola 6412 Digital Comcast Receiver, to a standalone Philips Tivo. After checking and double checking, it seems to me that I'm getting a better picture, from the Tivo to TV, on composite video than on S-Video. Is that normal? I always thought the picture quality would be better on S-Video. It is a fairly common misconception that a S-Video connection will always give a better video signal than a composite video connection. afaik, if the manufacturers always stuck to the real specs, s-video video is *always* superior to composite video problem is that there's a cheap way to offer both connects on a unit (for composite and s-video) which degrades one or the other (afaik, from one ref that i've seen here in the last year) in my own firsthand limited knowledge (and experience) it's best to try both and go with what works best. for me, so far, that's been s-video (one instance) bill Given an equivalent quality video source, then it is usually true that the quality of the video signal passed will improve as one goes from composite video , to S-Video, to component video to digital video ( DVI or HDMI). However, this order may change depending on the length and quality of the particular video cable and in some cases it will be very hard to notice any difference. The other reason the generalization is not necessarily true is that the quality of the source is not always the same. In particular, cable boxes often have a problem with analog cable channels. The S-Video, component video and digital video outputs of a cable box require processing of the analog video signal which would otherwise be done in the TV or, in your case, by the Tivo. Cable boxes have been notorious for their poor processing of the analog video channels and, in a lot of cases, it is better to have the necessary processing of these signals done in devices with better quality processing such as the better quality TVs or recorders. This will depend very much on what devices you have, their video processing capabilities and the type of video connection you use. Another factor in this equation is that analog TV displayed on large screen TV's from the same distance that one would view a smaller TV means that the large screen will show imperfections in the TV picture quality more than a smaller screen does. Your cable box is for HD pictures so if you have a large screen TV then you will be bothered more by the poorer inherent quality of Standard Definition TV exasperated by noise introduced by the poor video processing in the 6412 cable box. Note there are reports that the newer model 6412 cable box with the HDMI output has better processing of the analog channels so this problem is eliminated or less significant for those cable boxes. Unfortunately, you really have to try the particular combinations you have available to see which connection has the least problem. There is also the ease of use factor to consider. I have my 6412 cable box connected with component video and composite video. I use the component video for SD and HD digital channels and composite video for analog cable channels. This gives me the best video quality. However it is a nuisance to change the video source on my TV so I often will not bother to switch video sources when changing to a analog channel from a digital channel unless it starts to bother me too much or unless I know I going to stay on an analog channel for a long time. Alan Bealby Remove no_spam from my E-Mail address |
S-Video vs Composite Question
"Alan" wrote in message ... Huh? Cable, ANALOG satellite (mostly the big dishes), and laser discs (not DVDs), source composite signals with luma and chroma combined. There is, as you say, little advantage to using a cheap filter in those units instead of a good one in the television. I was referring to the receiver end. It decodes the MPEG compressed signal into YUV. To get composite, it has to be converted back to luma and chroma and combined. The seem to find a way to screw it up at that point. Try it sometimes. You will often find that the S-video output of a cable box or sat receiver is worse looking than the composite. DVD, Dish Network, DirecTV, most other digital satellite signals, ATSC OTA digital, all have the signals coded separately. The mpeg decoder outputs components, which have to be converted and combined to produce composite. In the case of these units, it is almost always better to *not* combine the signals to composite -- using s-video would be a preferable choice (though using component would be even better). Video is encoded as component. Ideally, one would not want to combine to composite after converting the YUV to YIQ. In the real world it might look better using the component outputs. This can be because the processing is sloppy in the source box, resulting in really lousy results. The bottom line is that it depends and you have to try it. I have seen enough times that the composite looks as good or better to not assume that S-video is the way to go. Sometimes the combined signal comb filtered in the set just looks better. The specifics of processing are quite variable with equipment. I would recommend trying both s and composite connections to see which is better. When using VHS units which record the luma and chroma discretely there will likely be an improvement. With the previsously mentioned sources, it depends, but the set will usually have the better filtering. Yes, as you note, vhs, beta, 8mm/hi8, all use color-under recording so there is some advantage to not combining the chroma and luma back together for the trip to the display. Alan Like I said, it depends. The bottom line is use component when you can and don't assume that S-video is better than composite. Leonard |
S-Video vs Composite Question
Leonard Caillouet wrote: "Alan" wrote in message ... Huh? Cable, ANALOG satellite (mostly the big dishes), and laser discs (not DVDs), source composite signals with luma and chroma combined. There is, as you say, little advantage to using a cheap filter in those units instead of a good one in the television. I was referring to the receiver end. It decodes the MPEG compressed signal into YUV. To get composite, it has to be converted back to luma and chroma and combined. The seem to find a way to screw it up at that point. Try it sometimes. You will often find that the S-video output of a cable box or sat receiver is worse looking than the composite. DVD, Dish Network, DirecTV, most other digital satellite signals, ATSC OTA digital, all have the signals coded separately. The mpeg decoder outputs components, which have to be converted and combined to produce composite. In the case of these units, it is almost always better to *not* combine the signals to composite -- using s-video would be a preferable choice (though using component would be even better). Video is encoded as component. Ideally, one would not want to combine to composite after converting the YUV to YIQ. In the real world it might look better using the component outputs. This can be because the processing is sloppy in the source box, resulting in really lousy results. The bottom line is that it depends and you have to try it. I have seen enough times that the composite looks as good or better to not assume that S-video is the way to go. Sometimes the combined signal comb filtered in the set just looks better. The specifics of processing are quite variable with equipment. I would recommend trying both s and composite connections to see which is better. When using VHS units which record the luma and chroma discretely there will likely be an improvement. With the previsously mentioned sources, it depends, but the set will usually have the better filtering. Yes, as you note, vhs, beta, 8mm/hi8, all use color-under recording so there is some advantage to not combining the chroma and luma back together for the trip to the display. Alan Like I said, it depends. The bottom line is use component when you can and don't assume that S-video is better than composite. Leonard For a moment let's throw out the fact that some manufacturer's do a better job than others at processing video. Theoretically, what is best? |
S-Video vs Composite Question
"DanR" wrote in message . com... For a moment let's throw out the fact that some manufacturer's do a better job than others at processing video. Theoretically, what is best? Theoretically, FWIW, keeping the luma and chroma apart would be best. Leonard |
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