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06-02-2014, 10:47 PM
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What is the best conversion method for analog video? DV or MPEG-2?

This is a question that has been debated by video professionals for the last 15 years.

DV was developed in 1995 as a codec that would allow video to be shot in and transferred to digital quite easily. TV Networks, such as NBC and Fox in the US and the Miracle Channel in Canada, have been using one of the DV for their Standard Definition newscasts and some programming since the late-1990's. A number of community access channels across the U. S. and Canada adopted the DV format as well. DV is a broadcasting standard. There have been three DV variants released: DV (Mini-DV just uses a smaller tape shell for this), DVCam and DVCPRO, aside from some minor technical details, all three variants used the exact same DV codec.

MPEG-2 was also developed in 1995 as an improvement of the MPEG-1 codec. MPEG-1 had been developed to encode video onto a CD, however the quality of the video was about that of VHS. MPEG-1 was also used at higher encoding levels by some digital satellite/cable channels, however, this encoding scheme has been discontinued in favor of MPEG-2. Sony used MPEG-2 compression on it's professional Betacam SX and MPEG IMX lines, as well it's consumer level Micro MV format. However, unlike Micro MV, which sampled it's luminance and chrominance at a 4:2:0 level, just like DVD, Betacam SX and MPEG IMX sampled their color at 4:2:2, plus their data rate (Mbps) is much higher than Micro MV or DVD. For this article these professional formats will not be mentioned anymore, as this discussion is about MPEG-2 at the 4:2:0 level, which is used for DVD, Micro MV and digital television broadcast.

4:1:1 or 4:2:0?

In all digital video, the luminance channel (a.k.a the black and white channel) is represented by a 4. This allows for the ratio's to be more easily remembered, otherwise we'd have ratio's of 1:0.5:0.5, etc. The next two numbers represent the compression of the chroma channels (the color); 1 means that the color is sampled at a quarter of the resolution that the luminance is sampled at, while a 4 means that the chroma is sampled at the same level as the luminance.

DV encodes its luminance and color at a 4:1:1 ratio, which means that the red and blue channels are sampled at only a quarter of the luminance channel. As DV's luminance is, in analog terms, 13.5 MHz; this means that both of it's chroma channels are sampled at a 3.375 MHz level. This provides better resolution than NTSC or PAL broadcast signals, as combined DV's chrominance is 6.75 MHz.

At 4:2:0, MPEG-2 also encodes it's luminance at 13.5 MHz and chrominance at 6.75 MHz, but unlike DV, MPEG-2 co-sites, or averages it's chrominance channels into one stream. To us an analogy, this is similar to how S-VHS played back it's video in the analog realm, where the luminance was in it's own channel/signal, but the choma channels were combined into one signal. For MPEG-2 this means that the vertical resolution of the chroma is greatly reduced; and for analog to digital conversions this is not good, as the interlace video format of, VHS for example, has already reduced it's vertical resolution. With interlaced video it is not clear whether 4:2:0 samples 2 side-by-side lines in a frame, or if it samples two side-by-side lines in a field, thereby skipping over lines (interlace is an old compression scheme from the 1940's, originally designed for analog television transmission, that split a frame of video into two, and sent one "field" ahead of the other).

Now then, there is one exception for DV, since European PAL DV/DVCam uses 4:2:0. 4:2:0 seems to work better with PAL and SECAM's already reduced chroma resolution, however, no one really seems to know why, since PAL DVCPRO25 uses the 4:1:1. As a result, PAL DVCPRO25 decks have the dubious distinction of having to convert from 4:2:0 to 4:1:1 for playback. (For more information I would recommend checking out Adam Wilt's DV FAQ.)

Compression Ratio

For comparison's sake, uncompressed digital video is usually stored at a compression ratio of 2.1 or 3.1; most sources give 2.1, but some indicate that it is as low as 3.1. Digital Betacam (Standard Definition) and XDCAM (High Definition) tend to shoot at this level, and some editing, especially for theatrical release, occurs at this level, although uncompressed uses a ton of memory

By comparison, DV compresses its video at a 5.1 ratio, whereas MPEG-2 compresses at a 10:1 ratio. While 10:1 is okay for final delivery, for editing this requires a ton of computer power, and causes generational loss.

What Does This Mean For DVD Transfers?

When you put this together, if you capture your video just in MPEG-2 4:2:0 (which is what most people do with set top DVD recorders and the $20 dollar department store capture devices), you are transferring in low quality. By capturing in DV, then going to MPEG-2, I am able to capture in a higher quality, and then put the video onto DVD. This is analogous to, in the 90's, shooting your family's home movies on VHS-C and then making copies for family members onto VHS from the VHS-C. You would not use the VHS-C to make a good copy for Grandma, since you would be losing quality: the better way would be to transfer the VHS-C to a Hi8 tape, and then use the Hi8 tape to make another VHS copy. So you end up with a video that looks just as good, if not better than the original tape.

Software or Hardware Encoding

Also, for formats such as U Matic, Betamax, VHS, S-VHS, Video8 and Hi8, the video is recorded on the tape in a composite format, which is already a compressed analog signal. Most set-top DVD players only capture analog video by the yellow composite RCA or RF inputs, and this leads to video that does not show off its full potential. While set top DVD recorders do use hardware encoding, it is usually the cheapest hard ware out there (usually equivalent to a camera that has a 1 CCD for capturing video). Unless you plan on watching your DVD via your DVD player's composite connection, you'll find that DVD's made in this fashion have horrible chroma problems when played back by S-Video, Component or HDMI.

The various USB converters that are sold in department stores for around $20 dollars tend to use software encoding more often than hardware encoding. Software encoding tends to soften an image and never gives you the quality that you are looking for. These types of converters are better suited for just capturing TV shows from analog/digital cable than for converting analog video to digital for your precious memories.

Here at Trevor Thurlow Productions one of my main converters is the Grass Valley Canopus ADVC-300. It is a high-quality, broadcast level analog-to-digital DV converter, that uses hardware to convert the signal to digital before sending it to the computer for burning to a DVD. I know that there is one company out there that tries to say that it is a poor converter, however, I have tried several converters over the years (including set top DVD recorders) using the DV and MPEG-2 codecs, and I have never found a better converter than the ADVC-300. The chroma's very stable (especially with video from VHS and U Matic) with no chroma bleed, and the converter delivers a very sharp picture.

Even for editing I find with my own projects that I get a better quality image when I'm using footage (even footage from DVD) that's been captured and imported with DV. With DVD, if I just copy the VOB or use another program to convert the MPEG-2 4:2:0 image, I find that I end up with very choppy video that also looks like it came from a VHS recorded in the SLP mode. This is due to MPEG-2 recording in the inter-frame GOP mode, where it only records (for example) frame 1, and then frame 5, and then it relies on information from both those frames to create the missing frames. So everytime that I apply an effect to an MPEG frame, the computer has to uncompress the video, fill in the missing frames, apply the effect, and then recompress the image: this leads to a large loss of visual information and sharpness. DV, on the other hand, records each frame and compresses it (sort of like how a JPEG is compressed) in intra-frame compression, so it has access to every frame and the rendering does not cause a major quality drop to its image.
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06-02-2014, 11:52 PM
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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:
unlike DV, MPEG-2 co-sites, or averages it's chrominance channels into one stream. To us an analogy, this is similar to how S-VHS played back it's video in the analog realm, where the luminance was in it's own channel/signal, but the choma channels were combined into one signal.
That isn't what "co-siting" means at all, and in fact DV 4:1:1 and DV 4:2:0 both co-site their chroma while MPEG-2 4:2:0 doesn't in the vertical direction. All it means is that the chroma sampling is done at the same location as a luma sample. MPEG-2 is still a YCbCr system while what he's describing would be YC.
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06-03-2014, 01:03 AM
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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.

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06-03-2014, 09:12 AM
sanlyn sanlyn is offline
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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.
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06-03-2014, 11:16 AM
premiumcapture premiumcapture is offline
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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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06-03-2014, 01:21 PM
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Quote:
Originally Posted by premiumcapture View Post
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.
I used to have some, years ago, that was intended for the site. But a computer crash many years ago destroyed them. I had 99% recovery, but those files were in that 1%. Several items for digitalFAQ.com were destroyed, along with some various Smurfs-related files (games, comics, images, etc). The "My Documents" folder was hardest hit in the crash.

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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06-04-2014, 03:51 AM
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Quote:
Originally Posted by premiumcapture View Post
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.
I have some samples, not sure hot these managed to end up 720*576. They should be 720*480.

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:



This is from the cam over S-video going into a Canopus 110:




My advice has always been DV especially for newbies, if you are using a Canopus it just works each and every time.
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06-04-2014, 06:47 AM
sanlyn sanlyn is offline
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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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06-04-2014, 07:49 AM
thecoalman thecoalman is offline
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Originally Posted by sanlyn View Post
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.
Yes I understand the point, the DV source provides a control. The second sample is not renecoded per se because it's being encoded from an analog source.

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.
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06-04-2014, 08:48 AM
sanlyn sanlyn is offline
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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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06-04-2014, 09:20 AM
thecoalman thecoalman is offline
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Quote:
Originally Posted by sanlyn View Post
Clarify, if you would. I thought you said the source was never in analog format.
It isn't until output over s-video. I'm using a DV camcorder to output the DV over s-video into the Canpous. When I said it was never in analog format I was referring to the source.

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:
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.
It's not ideal but if were to do it again I's use .png. Those are from 8 years ago. That said the original and the capture went through the same editor, .jpg compression settings etc. One other thing to note is that's it's not the exact same frame.
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06-04-2014, 10:43 AM
sanlyn sanlyn is offline
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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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06-04-2014, 02:49 PM
thecoalman thecoalman is offline
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b) the same DV source -> capture device -> lossy re-encoded DV
Not really because that would imply it's already been encoded. The DV source is of course digital but is output over s-video, that is analog and a substitute for the VHS. Again this provides a control because now you can compare the capture to the source.

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06-04-2014, 03:29 PM
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Originally Posted by thecoalman View Post
Not really because that would imply it's already been encoded. The DV source is of course digital but is output over s-video, that is analog and a substitute for the VHS. Again this provides a control because now you can compare the capture to the source.
Thank you for posting the pics. While the topic wasn't necessarily on native DV video, e.g. captured on a DV camcorder, the S-Video image comparison does help, because after all, while the difference may not be as stark as VHS to Canopus, it still does provide a good comparison.

Any chance you can try a VHS tape for us to take a look at too?
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06-04-2014, 03:47 PM
thecoalman thecoalman is offline
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Originally Posted by premiumcapture View Post

Any chance you can try a VHS tape for us to take a look at too?
The issue is what are you going to compare it too? I can't post VHS. You have no clue what the source looks like.

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.

Videotape noise filtering suggestions needed
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06-04-2014, 05:19 PM
sanlyn sanlyn is offline
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Originally Posted by thecoalman View Post
Not really because that would imply it's already been encoded. The DV source is of course digital but is output over s-video, that is analog and a substitute for the VHS. Again this provides a control because now you can compare the capture to the source.
Sorry, incorrect on all counts. DV source is lossy encoded video to begin with. Playing it as analog and saving it again to DV is another lossy encode, and DV under any circumstances is a long way from being "like" VHS source.
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06-04-2014, 09:06 PM
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Originally Posted by sanlyn View Post
Sorry, incorrect on all counts. DV source is lossy encoded video to begin with. Playing it as analog and saving it again to DV is another lossy encode, and DV under any circumstances is a long way from being "like" VHS source.
The two photos he shared demonstrate an analog capture vs. a digital transfer. While not VHS as preferred, it does show, though only slightly due to the codecs matching, the differences in quality. The canopus can copy DV directly via firewire or capture over analog, so he is not in the wrong.
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06-04-2014, 09:37 PM
sanlyn sanlyn is offline
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Quote:
Originally Posted by premiumcapture View Post
The two photos he shared demonstrate an analog capture vs. a digital transfer. While not VHS as preferred, it does show, though only slightly due to the codecs matching, the differences in quality. The canopus can copy DV directly via firewire or capture over analog, so he is not in the wrong.
Enjoy. I've seen his VHS->DV captures, and I've seen yours. No thanks.
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06-04-2014, 09:39 PM
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Originally Posted by sanlyn View Post
Enjoy. I've seen his VHS->DV captures, and I've seen yours. No thanks.
I've never captured to DV. What are you talking about?
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06-04-2014, 10:37 PM
sanlyn sanlyn is offline
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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.

Last edited by sanlyn; 06-04-2014 at 10:48 PM.
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