DV is best to convert VHS? Do you agree with this article?
http://www.trevorthurlowproductions.ca/dvmpeg.php
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There are a bunch of opinions in that article so I don't think anyone is going to agree with all of them.
The author makes some objective technical errors, for example: Quote:
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Always quote the article here. Fixed it for you.
DV = not for conversion! DV was never invented for transfer. That's BS aka myth. DV was a shooting format. Period. The latter half-cocked conversion idea was completely Canopus. Until the craptastic ADVC boxes came along, the only way to capture as DV was using Matrox or Canopus NLE cards in ways for which they were NOT intended. The intention was (A) working real-time with shot DV, and (B) capturing uncompressed or lossless. You'd then integrate everything in Premiere 6 and export to MPEG or SDI. Due to the somewhat willynilly nature of the devices, you could also capture DV. After the Matrox/Canopus NLE cards had been on the market for a while, Canopus added a DV-only product to their lineup, as a cheaper option for folks that were trying to capture analog on archaic IDE Pentium III systems. In those days, you needed a RAID array for better capturing. By the time the IDE 7200 (and later SATA) Pentium 4 systems were out, such nonsense should have died off as the inferior method that it was. But for some reason -- mostly Canopus BS marketing ("audio lock", etc) -- it persisted. To this day, it's mostly only stubborn "old timers" (pre-2004, a decade ago) that insist it's the best method. In all honesty, it's mostly them (still!) trying to justify that shitty method as good. It was indeed an eventual broadcast standard, as stating in the first paragraph -- but ONLY for shooting. Big difference. For capturing, uncompressed (or lossless) was, is, and will probably continue to be best. The runner up format for capture/transfer is MPEG, not DV, due to the way the color information is recorded, and because of the GOP (short of long) use of variable bitrates. Mhz? My head hurts... I get tired of people that keep parroting the 90s era Canopus marketing doublespeak about the Mhz on the image. That doesn't matter. What matters is (A) how the colors are stored, and (B) the bitrate specs. Nobody should give a crap about the Mhz of the analog system. This is digital now, not analog. Unless you're a capture card engineer, not a capture card user, much of the analog spec info is trivia more than anything else. MPEG is NOT high compression! The idea that "MPEG = 10:1 compression" shows a complete lack of understanding about MPEG. For example, I-frame only or IP GOP is/was a preferred studio editing format, especially at Sony. If you actually worked at a studio, you'd know this. These days, quite a few MXF files are delivered at 4:2:2 MPEG-2 MP@HL, and at 25+ Mbps bitrates. To say something as stupid as "MPEG = 10.1 compression" is to have only read the help file from a DVD authoring program. In the world of video, it's a dumb as saying the earth is flat. DV to MPEG = double loss! That's horrible. You start with 4:2:2 (assuming VHS/Video8 sources), compress is down to 4:1:1, and then compress that down to 4:2:0. It's the video equivalent of putting your color quality through a shredder first. It's reduces the hell out of the chroma by double converting it needlessly. Pick one! Either use 4:2:2 to 4:2:0, or simply start with 4:2:0 to begin with. Hardware = good! To say "software = bad" or "hardware = bad" is really stupid. You have to take each piece of hardware (the WHOLE workflow, actually!) and the software on a case by case basis. For example, with DVD recorders, Panasonic makes some of the worst encoder chipsets there are. Those nasty chips choke on everything from Half D1 to chroma accuracy. On the flip side, LSI Logic made some of the best chipsets around, and it's a shame that the recession killed them off last decade. They just could not compete with manufacturers that wanted to make crappy in-house chips to save $5. Zoran chips are also very, very nice. The hybrid software+hardware method used by the ATI All In Wonder cards (Theatre Rage/100 and Theatre 200 chipsets) is one of the best their is for analog conversions. Conclusion... When it comes to video, this person doesn't know his ass from his elbow. Yes, I'm being mean here. But after 10+ years of hearing this dribble, I grow tired of it. It's crap. This person is mixing up facts all over the place, and is doing nothing more than justifying his own purchase of the Canopus junk. That last paragraph makes no sense. Why is he "copying" VOB files? That's the WRONG method for decompiling a project for re-edit. It sounds as if he wants to convert MPEG-2 to DV, and back to MPEG-2. Yikes! That's what happens when amateurs start video services -- they have no idea what the hell they're doing. FYI: MJPEG or JPEG2000 is like JPEG. DV is not even close. MPEG I-frame would also be similar to JPEG, and be a better choice than DV. Not only is MPEG color better, but the 4:2:0 is cross-platform (NTSC/PAL), which is important in a studio setting. You should also re-extract an MPEG to lossless or AVI before dumping in an NLE. Yes, trying to live edit an MPEG (or even a DV file, to be honest) is a test in patience! Better yet = only editing the MPEG parts as needed, then seamlessly re-integrating everything in an MPEG editor post re-encode. That way, you only introduce re-encoding where needed, and at the merges -- not wholesale on the entire file. But that's not the lazy way, of course. Even studios make dumb mistakes. I'm irked by the pathetic chroma work done on the Critereon release of "It's A Mad, Mad, Mad World". It's like they just failed to process the last leg of the project for the uncut edit, as it has horrible rainbows everywhere in the footage. Avisynth could have easily fixed that. |
Amen. I don't think the reply is mean. Rather, it's simply to the point. If lordsmurf doesn't mind, next time I see a VHS->DV project I'd like to reference the above post, along with several others that are similar and with even more detail. I've had and seen countless debates with those who say they "can't see a difference" between capturing VHS to DV and capturing lossless. DV fans can't see a difference, perhaps, but many people can.
Thanks, lordsmurf. Again. |
One thing I haven't seen that would probably help a lot of people make the right decision is a tape captured in DV and a tape captured uncompressed. There are few if any canopus samples available, so if anyone does have a sample to put up it would be appreciated.
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Recreating clips would require another ADVC, which was never budgeted for. In addition to be one of the worst devices, it's also one of the most expensive. So it's double punishment! We have the DataVideo DAC-100 still, a Canopus rebadge/clone, but it's finicky, and sometimes will not power on. It'd have also required a large time investment to tediously create the various clips. And it just never happened. I would not mind redoing a few, but it would require the donation of an ADVC 50, 100 or 300 series. The last test showed the 300 series, and the horrid abuse the filters do to video, in addition to DV loss. |
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In any event this is direct from the DV file transferred from the cam over firewire, this is the original source. It was never analog: http://www.digitalfaq.com/forum/imag...13/07/dv-1.jpg This is from the cam over S-video going into a Canopus 110: http://www.digitalfaq.com/forum/imag.../canopus-1.jpg My advice has always been DV especially for newbies, if you are using a Canopus it just works each and every time. ;) |
Hmm. Perhaps you don't understand the point of this thread ? ? The question deals with analog VHS -> DV vs analog VHS -> lossless. However, the samples do prove the point that re-encoding DV involves a quality loss. No one can doubt it from your samples.
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Image 1: Straight transfer over firewire. Image 2: Camcorder >> S-Video >> Canopus110 In a sense image 2 is substitute for your VHS source and since we have image 1 we know exactly what it should look like. ;) |
Clarify, if you would. I thought you said the source was never in analog format. I also thought this was a discussion about comparing VHS-to-DV and VHS-to-lossless. Is the source VHS? Is the top image a DV capture from that VHS source? Is the bottom image a lossless capture from the same VHS source? What your source proves is that isn't a good idea to capture lossy DV source to lossy DV. I think most readers here already know better than that.
One might also note that while you can deduce a few things from a still frame capture, a still image isn't the same thing as a video source with motion. |
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If you are going to do any real comparisons you'll need to do something similar because you need to know what the result should be. If I had another capture card I could for example capture that from S-video too. Now we can compare the Canopus capture, the capture from the other card and compare them both to the source. Quote:
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Thanks for clarification. The original request was for this:
a) analog VHS -> capture device -> DV capture b) the same analog VHS -> analog capture device -> YUY2 lossless media (e.g., uncompressed, or huffyuv or Lagarith lossless, etc). What you posted was: a) DV source -> DV copy device (Firewire ?) -> exact DV copy b) the same DV source -> capture device -> lossy re-encoded DV Where is the VHS original? :) |
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Any chance you can try a VHS tape for us to take a look at too? |
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I have all that equipment stored, not digging it out. Besides my VHS deck need work. There is some sample captures here but be aware the VHS tape was a copy. http://www.digitalfaq.com/forum/vide...html#post21873 |
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Hold on. Whose VHS->DV captures were linked earlier? I refer to those, whoever they belong to.
Should we take it, then, that your request for VHS source comparisons is now null and void? Since VHS data is stored as a flavor of YCbCr, uses a different color matrix for translation to other color systems, isn't lossy source, and has several other characteristics that distinguish it from DV (tape surface and head noise being two of VHS's DV-unfriendly problems), I guess this means that comparing genuine VHS source processing is no longer part of the question. Perhaps if someone would play a DVD or standard-def AVCHD thru s-video and capture it to DV, would that serve as an equivalent analog capture source? How about DivX and Xvid? I also take it that capturing to huffyuv lossless media is no longer relevant. So....since all of the source variables have changed, and many of the hardware components that would be used for VHS->lossless capture are also removed from the equation, then the original proposal no longer exists. What remains is a different question. The images demonstrate that it's a bad idea to "capture" DV by decoding it in an analog circuit and re-encoding it thru a Canopus DV encoder. It's always better to just transfer or otherwise make an exact copy of a lossy digital source. One might also cast a tad of skepticism about the posted images: they are not from the same moment in the video. Oh, well. I must apologize for misinterpreting your original proposal and being a little slow to track all of its modifications. However...Like many people I'm pretty firm in my belief that VHS is not like DV, and DV is not like VHS. They aren't just different breeds. They're different species. |
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