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About ginger_marianne

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  1. I guess what I would say to the OP is if your cable/wire is around 10 feet (or maybe a little higher), don't even factor impedance into the equation. Also, you probably don't have to worry about shielding unless you actually notice interference. Impedance mismatches generally subtract from the image (i.e. the full signal is not being realized because of losses). Interference adds to your image. If you need shielding for your cable (due to interference), you probably don't have to worry about the characteristic impedance of the cable. With shielded cables (e.g. coaxial), I'm not sure how much of the bulk of the cable is actually used to maintain tight tolerances for the characteristic impedance. There are also other ways to cancel out interference, such as twisted pairs.
  2. True. But on the ground, going from receiver to monitor/recorder, you probably have no need for shielding. It depends on the application. And when shielding is used, it probably doesn't have to be in the form of a thick cable with 75 ohm characteristic impedance, as long as the run is short enough. My understanding of video cables (limited as it is) is that cables are generally shielded to maintain characteristic impedance within tight tolerances (and not to prevent interference from outside sources). Correct me if I'm wrong.
  3. I remember reading that it's irrelevant what type of wiring you use if you're under 1/10 the wavelength of the maximum frequency you're using. In other words, losses due to impedance mismatches are minimal when the wire length (regardless of the type) is under 1/10 the wavelength. Assuming a frequency of 10 MHz for composite video, the wavelength would be ~ 300/10 meters (or 30 meters), or a little under 100 feet. So, based on this, you would be able to use any wire up to 10 feet or 3 meters with virtually no loss. Is this correct? Something that has confused me in the past is why people talk about the importance of having proper connections. More specifically, I've heard that RCA connectors don't have a proper 75 ohm impedance, so BNC is much better. But based on the above, the signal is carried over such a short distance over the connector that it would seem to make virtually no difference what connector you use or how many connections you have to make to get the signal from point A to point B, at least for composite video. So, I'm a little confused about this. Just to add to what Kilrah said, I ran some experiments with composite video and wire length, and I was able to go well beyond 10 feet with just magnet wire (very small caliber and unshielded) with seemingly no loss (at least when viewed on my TV). p.s. Let me add that the wavelength of 30 meters (for 10 MHz) is through a vacuum. The wavelength when the signal is carried over wire is about 20 meters. But my calculations above are still valid because some people use 1/4 wavelength as the cutoff instead of 1/10 wavelength. So, you could conceivably say that 5 meters instead of 3 is the cutoff for composite video transmission. These are very gross calculations.
  4. I've thought about it. I just won't do it. Personally, if I produce something, I don't want to do it again. It's a lot of work. Deleting the source file gives me a sense of finality. Also, I store all my files in triplicate (3 hard drives) with an indexing system and MD5 hashes (of all files). If it's worth keeping, I do this. If it's not, I don't keep it at all. Doing this process on hundreds of hours of DV would be too much. I suppose I could alter my system and just keep one copy of the DV files. But it's not for me. If the video was already produced with transitions and titles and you deleted the source file, then I think doing basic cuts on the mpeg-2 would work if done properly. After all, you already have some transitions. Most videos can handle some basic cuts after that. If the video was initially recorded as an mpeg-4 (on one of those cheap recorders), I would forgo fancy transitions and use basic cuts. After all, the loss in quality of re-encoding an already very compressed file would not be made up for by nice transitions and titles. Also, I'm not entirely sure it's not possible with some creativity to add transitions without re-encoding most of the file. For instance, I took a sample mpeg-2 capture from TV. I split the file into 2 clips with VideoReDo. I didn't just split it, I split it in the middle of a word. The narrator was saying "confusion". The first clip ended at "con". The second clip began with "fusion". I re-combined the 2 clips and it was seamless. The video went back together perfectly. And the word "confusion" sounded perfect. What does this mean? Well, if you want to create a transition in an mpeg-2, just cut out the few seconds where you want to put the transition in. Re-encode that few seconds with a transition, then re-insert it into your video. Simple and you don't have to re-encode your video. And it should look great. Just make sure that the re-encoded part perfectly matches the rest of the video. I'm not saying this is completely practical, but it's definitely possible. So, I wouldn't say it's mandatory to re-encode the whole video. And besides that, my understanding is that basic cuts are the most common types of transitions anyway in Hollywood movies. I think we agree on most things. As for the rest, we agree to disagree. Thanks for the debate.
  5. That's a good strategy if you can do it. But how many people who would ask the type of questions in this thread would\could actually do that? And besides, that could get very expensive. Depending on how much video you produce, that could require a lot of tapes (or more likely hard drives). DV takes up 4 times more space than DVD compatible mpeg-2 (and maybe 8 times more space than h264 or VC-1). I just wouldn't be able to do that, although I wish I could. You're right that the newer codecs are very compressed, so frame accurate cutting is probably not possible. But it is possible with mpeg-2. That's another reason why mpeg-2 is a good compromise for SD and DVD is a better choice for me. And when a good encoder is used (with the proper settings), the rendered mpeg-2 is quite acceptable for me (not a huge quality difference from the original source file). The only problem is when you try to re-encode that mpeg-2 at some later point. Obviously, the DV is a better choice if you plan to re-encode. But, at some point for me, I just have to say I've done enough with this video, and I don't want to do any more work on it. And don't forget that most people probably won't even take the bother to record in DV to begin with. Most will probably record in mpeg-4 and maybe some in mpeg-2 (which is usually a better choice than mpeg-4). Then most of those will probably re-encode their already highly compressed video. So, I definitely think it's worth mentioning ways to cut video rather than re-encode. Or at least mention that it's possible and relatively easy to do. As an aside, perhaps your observations about the quality differences (vs size) between mpeg-2 and AVC/h264 are only in the world of high definition. Or perhaps they only apply when real-time encoding is done, as in a camcorder. Because I would say that when I take a DV source file and encode to mpeg-2 and AVC/h264 (obviously in SD), the difference in quality vs. size is obvious. AVC wins hands down. Also, consider that in SD, mpeg-2 recorders (e.g. ChaseCam PDR100) often perform markedly better than mpeg-4 recorders, and that probably has little to do with the quality of the codec and everything to do with the processing power it takes to encode in real-time in those formats. All things considered, when you look at all the factors (size, quality, compression, processing power, ease of editing), I like mpeg-2 the best, especially in SD. Quality good enough for archival (at least for me), size small enough for distribution (with the added benefit of being DVD compatible), and frame accurate cutting possible. In short, it's perfect for SD, in my opinion.
  6. I actually looked into this a little bit more, and there is actually a problem with some encoders, such as Cinema Craft Encoder, and the field order. First of all, all of my stand-alone DVD players can play both BFF (bottom field first) and TFF (top field first) just fine, so it's not necessarily an issue of which one you pick, although TFF is probably the more conventional choice. The problem arises when the flag set on your mpeg-2 file is mismatched with the way your mpeg-2 is actually encoded. For, instance, if it's flagged as TFF but actually encoded as BFF, then you'll have a problem with stand-alone players. The picture will look jittery. Another problem with this is that the file will play perfectly on your computer monitor. As far as I can tell, there's actually no reliable way to detect this problem until you burn the DVD and play it on your TV. The problem won't even show up if you have a TV out on your video card. The only reliable way to detect the problem is to burn a DVD. I suppose it may show up on a computer monitor if there is something wrong with the mpeg-2 codecs installed on the computer. This usually occurs with encoders that don't detect the field order of the input file. It's expected that the user knows the correct settings with the particular input file. With CCE's default settings, it sometimes creates a mismatch and it sometimes doesn't. It depends on the field order of the input file. I'm not sure if this varies based on the version of CCE you use. The solution is simple. If the DVD you burn looks jittery, use a program called ReStream to change the field order. If it was previously flagged as TFF, then change it to BFF. If it was previously flagged as BFF, then change it to TFF. The change can be verified with GSpot. And no re-encoding is required. It's simply a problem with the flag. A simple preventative measure is not to delete the original source file until you're sure the DVD plays correctly on a stand-alone player. Possibly burn a small sample to a DVD to verify.
  7. That's true. Virtualdub is not a proper editor. But I do a lot of video manipulation. The fact for me is that I won't encode a video into a format unless I know that I'll be able to cut out parts or rearrange it later without having to re-encode it. Let's say I choose divx/avi format now for a video that I make. I want to know that 10 or 20 years from now I'll be able to manipulate it, cut out parts, etc. while still maintaining the original quality. I can't tell you how often people will re-encode a video every time they want to perform even the most basic tasks. Most people can't seem to grasp the fact that once a video has been edited and produced (i.e. compressed), you likely don't have to re-encode it to modify it, split it into clips, or rearrange the sequencing. So, that's why I stress programs like Virtualdub (avi), VideoRedo (mpeg1/mpeg2/VOB), IGCutter (wmv), etc. more than other types of programs (e.g. encoders). You should have a program like these for any format you choose to compress your video into. Notice that I don't mention one for mpeg4. That's part of the reason I'm not very enamored with mpeg4 at this time. It's a pain to deal with. I guess I sound like a broken record, but I really do consider this very important. I personally won't give a procedure for producing a video without mentioning one of these programs (because the re-encoding problem is so pervasive). And I stand by my statement that Virtualdub played a part in the explosion in popularity of the avi container. Just download some video from usenet and run it through GSpot. Chances are that it passed through Virtualdub at some point. And many people who download videos like to be able to split the video or make clips out of it. It's true utility for me is after the video is produced/compressed. Besides being a manipulator, it can do video conversions as well. But it's not a proper editor, so I guess I use the word "edit" loosely.
  8. I wanted to add a couple other things. There are no short cuts when it comes to dealing with video encoding/editing. I've wanted to pull my hair out several times dealing with this stuff. Unless you actually have some understanding of the topic, you'll never get the results you want. What I would suggest is picking a process (possibly from one of those described in this thread) and work with it to see if you can get the results you want. Something else I would suggest is possibly downloading some video (preferably those without copyright violations) and work with those. Use GSpot to see what type of videos they are. Try to edit/cut them and see how those results turn out. Another thing that I will mention is that some formats are much harder to deal with than others. For instance, AVI is very easy to deal with, thanks to Virtualdub. From my experience, MPEG4 is incredibly hard to deal with. The strange thing is that both AVI and MPEG4 carry the exact same codecs. For instance, h264 can be placed in both an MPEG4 and AVI container. In fact, you can convert between the two without having to re-encode (although the process isn't necessarily easy). The only way I've found to actually edit/cut an MPEG4 is to first convert it to AVI, edit in Virtualdub, then convert back to MPEG4. And I would argue that the only reason AVI is so easy to deal with is precisely because of Virtualdub. In my opinion, this is the most revolutionary program for video editing. This is probably the reason that AVI is so popular, even though the consensus among purists is that AVI is garbage and should be gotten rid of entirely. Until MPEG4 gets a program equivalent to Virtualdub, it will probably never take off in popularity. And from my recollection, the people who work on Virtualdub said that MPEG4 was basically a mess to edit. So, I don't know if MPEG4 is going to have that Virtualdub equivalent any time soon. There is another open source container format, OGM, that was supposed to compete with AVI and MPEG4. It also can hold the same codecs as AVI and MPEG4. It never took off, and I would argue the reason it didn't was because there was no good way to edit it. Easy editing is the key. And it usually only takes one good program, like Virtualdub. But I don't know if there's something inherent in MPEG4 that makes it very difficult to edit. As it stands now, I basically have a huge list of procedures for editing MPEG4. I've never had to make a list for AVI or any other format.
  9. I believe WMV is just a container for the codec. Actually, the VC-1 codec, which I mentioned earlier is part of the Blu Ray standard, is often placed in a WMV container. I've seen some samples, and it does provide excellent quality at a low bit rate. I used IgCutter (my lossless wmv/asf editor), and it worked perfectly with it. It's easy to check which codec specifically is being used with GSpot. If you encode VC-1 at 720x480 (or 720x576), there's a chance that it will be Blu Ray compatible without re-encoding, assuming you guess (or know) all the other settings needed for compatibility. WMV generally does provide excellent quality but finding tools to edit it (without re-encoding) is my main problem with it. It's not that it's a hard format to edit. It's just that Microsoft will harass and threaten anyone who writes software for it. I think Virtualdub supported wmv/asf until version 1.3. It's a little too proprietary for me, but otherwise provides very good quality. The only format I'm 100% comfortable with at this time is DVD compatible mpeg2. I generally capture in DV/mjpeg (preferably in Virtualdub if it supports my capture hardware), edit with Virtualdub, convert to mpeg2 (6+ Mbps, multiple pass) using Cinema Craft Encoder (pay software), and author the DVD using TMPGEnc DVD Author (pay software). TMPGenc also converts the audio to AC3 if you buy the separate plugin. As I mentioned before, I do my VOB/mpeg2 cutting using VideoRedo (pay software) and/or mpeg-vcr (pay software). TMPGEnc can also do basic cutting. VideoRedo is better than the other two because it always has flawless audio sync, it can combine mpeg streams into one, and is intuitive to use. TMPGEnc DVD Author, mpeg-vcr, and VideoRedo are all lossless, and none of them are capable of video encoding, although VideoRedo and mpeg-vcr are both very good at repairing both mpeg1 and mpeg2 streams. Between the two of them, I can fix virtually any problem with mpeg1/mpeg2/VOB videos. As I mentioned TMPGEnc can convert audio to AC3, and it is Dolby Digital branded. This is important to me because there have been problems with AC3 encoders in the past. Mpeg-vcr can encode audio to mp2. Since most of what I use is pay software, I don't expect anyone to go out and buy them, but with this combination of software, I feel I have mpeg1 and mpeg2 covered from every angle. As is pretty obvious, I hate re-encoding anything. I prefer to fix video while maintaining the original quality. Versions I use: TMPGEnc DVD Author 1.6, mpeg-vcr 3.14, VideoReDo 2.5. These are all very old versions. They've probably all been updated extensively, so my descriptions may not accurately reflect the current versions. I haven't looked for anything new because they all still work fine for me. I think VideoReDo is working on mpeg4 support, although I haven't been paying attention. As far as I know, there are currently NO mpeg4 editors that are anywhere near adequate.
  10. I've personally never de-interlaced mpeg2. They've always played properly for me interlaced. I was wondering which (if any) of these de-interlacing methods allow the mpeg2 to retain DVD compatibility? I would argue that there is absolutely no reason to use mpeg2 unless it is DVD compatible. Each of the other codecs that I previously mentioned can equal the quality of mpeg2 at a lower bit rate. Thanks
  11. I don't think anyone will tell you exactly which settings you should use because it depends on the hardware you have to work with. I can only give you 3 things you should look out for. 1. Capture: If you plan to do any editing (other than basic, lossless cuts) after you capture your video, then use the lowest compression codec you have available to you. A low compression codec will take a lot more space on your hard drive than mpeg2 will, but it will yield a lot better quality. Two good codecs that I've used are DV and mjpeg (720x480). After your capture, then you can convert to mpeg2 or h264, usually with much better results than if you had initially captured in mpeg2 or h264. As a general rule, the more compressed a codec is (i.e. most of the mpeg4 codecs), the worst the quality will be if you capture using that codec, and doubly so if you plan to do any editing (other than basic cuts, which can be done losslessly). Mpeg2 capture may yield better results than mpeg4 capture. 2. Editing: DV and mjpeg can be edited with much less quality loss than mpeg2 or h264. With DV, you can probably get away with multiple conversions (re-encodes) with little loss in quality. If you try to re-encode mpeg2 even once, you'll probably notice a considerable loss in quality. Although Kilrah has suggested that mpeg2 -> h264 or mpeg2 -> divx may yield better results than mpeg2 -> mpeg2. If you plan to edit mpeg2, I would suggest using something like VideoRedo or mpeg-vcr, which can do basic cuts without any loss in quality. h264 can also be edited losslessly, but the process is more complex. Unfortunately, real editing usually requires re-encoding, which is why DV is a better codec. 3. Final format: My two preferences are h264 (in mpeg4) and mpeg2 because they yield good results and they are likely to be the most future proof. Mpeg2 (720x480) is a standard for both DVD and Blu-Ray. And h264 is a Blu-Ray standard. Divx/xvid is also extremely popular. VC-1 is the third Blu-Ray compatible codec, although I have no experience with it and can't recommend it in any way. But supposedly it's on par with h264. These are probably the only codecs I would consider. In my mind, there's little doubt that h264 will eventually become the de facto standard. It gives you the best bang for the buck (i.e. excellent quality at low bit rate). So, it would be my recommendation to use this format, but not for capture. But, if you initially capture in mpeg2 and only want to do basic cuts (no re-encoding), then I wouldn't do any conversion. Any conversion you do will always result in quality loss. So, in short, if you have the proper hardware, my preference for SD would be to capture in DV or mjpeg and convert to h264/AVC (in mpeg4 container). As for what settings to use for the conversion, I'm still working on that myself. It's still an immature technology. My goal is to eventually make it Blu-Ray compatible (720x480 is accepted on Blu-Ray discs), but since I don't have a Blu-Ray burner or player, I'd only be guessing as to how to make it compatible at this point. Mpeg2 would be my choice if I'm still not comfortable with h264. As for whether to interlace or de-interlace, just try one of each and see how they look on your TV and computer monitor. But I don't believe you can de-interlace mpeg2 without re-encoding, which may reduce the quality. If I had to re-encode mpeg2 to de-interlace it, I wouldn't do it. I would de-interlace from my original source, before it's ever converted to mpeg2.
  12. Okay, I'll take your word for it. They shouldn't take up that much space anyway. Thanks
  13. Thanks for your response. Every recommendation I've seen has been to use capacitors with the LM7805, but to be honest, I have yet to see a lick of difference (for my application) with or without them. The signal looks the same as the original to me. But it wouldn't be the first time I've missed the obvious (has happened multiple times in this thread already). I'll just keep playing with it to see what I notice. But so far, I see none of the noise that occurred with the resistor. I'm trying to keep everything as small as possible. So far, the LM7805 hasn't gotten any more than mildly warm (if any heat at all). It was the same when I was using the resistors. The current is too low to produce much heat.
  14. Okay, I'm sorry if I'm posting too much. I tried the 5V regulator from Radio Shack. It's absolutely perfect. No capacitors are needed when used with the splitter. It provides a clean 5V. And there's no noise at all, even without a capacitor. And it's tiny. So, ignore everything I said previously about resistors. Thanks
  15. Update: In my quest to use this splitter with a 12V (+/-25%) source, I've made a couple modifications since my last post. I decided to lower the resistance from 440 ohm to 380 ohm (or 330 ohm) because the 440 ohm wasn't perfect around the 9V range. Also, I added a 100 uF capacitor from the ground to the +5V (pin 1 to pin 2 on the input side of the splitter). Again, I didn't modify the splitter and simply added the capacitor to the wiring. Apparently, adding the resistor introduces a small amount of noise (low frequency?). The thing about the noise is that it usually isn't visible. It would probably work fine with just a resistor and no capacitor. In fact, I watched TV for hours with this device using just a resistor, and it looked perfect. I only noticed it with one specific thing produced by my cable box. So, I added the capacitor, and it disappeared. A 10 uF capacitor improved it but it didn't disappear completely. Also, I want to make it clear that it was my adding the resistor that introduced the noise. If you just feed the splitter 3.1V to 11V, the output is always perfect. So, I found the simplest solution is to add 2 components to the wiring (no circuit board needed). Add a resistor to the middle wire feeding pin 2 (+5V) to reduce the voltage being fed into the splitter. Then add a 100 uF capacitor to eliminate the noise introduced by the resistor. The capacitor should be placed on the ground and +5V wires (feeding pins 1 and 2). The capacitor should be between the resistor and the splitter. It's actually very easy to build (just some minor modifications to a servo cable). I also want to emphasize though that if someone uses a splitter with even a small difference in current usage than mine (e.g. slightly different components), then a different resistor will be needed, or else too much voltage (>11V) can be supplied to the splitter, possibly damaging it. So, anyone attempting this should measure it for themselves (with a good multimeter), starting at a higher resistance and working your way down. Go with the highest resistance that works. There's also a very small 5V voltage regulator (7805) from Radio Shack that can take any input voltage from 7V to 35V and give you a clean 5V. All you need is the regulator and 1 or 2 capacitors. I haven't used it yet, but I've seen some good reviews. I decided to go with the resistor because I could make everything a little smaller overall. But a regulator is a safer option with a wider input voltage range. With a 380 ohm resistor, I get a range of approximately 9V to 17V. If someone can explain the noise introduced by the resistor, I would appreciate it. I don't fully understand it. But my guess is that small variations in current usage by the splitter induce small changes in voltage across the resistor (because the voltage across the resistor is dependent on current). So, does this introduce a low frequency AC component?
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