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  #1  
02-12-2010, 02:03 AM
Kereellis Kereellis is offline
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Hello again dear experts

Since I kept stumbling on difficulties to find properly working hardware, I've decided to let most of my homevideo tapes (the real precious ones) get ripped by a professional (although that doesn't mean I haven't learned a lot of useful stuff here that has helped in deciding on how I'd like to get it done, which proved useful in selecting a pro). In terms of analogue equipment, this guy seems to be the best choice there is available around here, since he has been passionately collecting and maintaining high end equipment (video brackets, tbc's etc.) for decades. Besides that, he's also the only pro I could find who didn't object when I asked him to rip to harddisk in such and such a way as I'd have done it myself. Most people offering their services in the field of digitalization sadly have proven to be either amateurs that like to make some easy money off their dvd recorders, or a few that stick to their own theories and methods and get touchy if you make a request that strays from that.

Anyway, for my reassurance I'd just like to check a few facts here (it'll be quite pricey after all) .
1. As a capture device this particular digitalizer uses a Datavideo DAC-10. Since I'd like him to rip in huffyuv, I'd like to make sure it isn't one of those devices that hardware-compresses to dv-avi forehand. In addition it would be nice to make sure if it's known to be 'accurate' enough. I also read the DAC-10 comes with an 'audio lock' function, but I'm not sure how those work. Perhaps by dropping/inserting frames or dynamically resampling audio like vdub? (For editing purposes I'd like to know if I'll end up with audio that's already resampled, if it'll be possible to tell).

2. Should I ask him if he monitors the tapes as he rips them? From how he said he'd rely on either automatic time/size limits for the files or rip the tapes as a whole, I got the impression he may not. For a higher tariff, he does use high end equipment that can correct chroma and luminance errors, but I'm not sure if they require manual operation. I'm personally just used to basic proc.amp settings (brightness, contrast and such) that often need adjustment in order to optimize the different types of recordings on these compilation tapes of homevideos (which is mostly required due to the difference between inside/outside recordings, and a few tapes that contain recordings from two different camera sources, that each had their own quirks). I also don't feel like paying extra for the optimization of one type of recording that is detrimental for others on a tape.

3. What kind of system would theoretically suffice for playing more compressed huffyuv files? I intend to request rips compressed with the settings predict gradient or preferably even median, but I've experienced a slower playback of such files once before due to unknown causes (with my currently installed ATI AIW 9800 PRO that is, perhaps the 9600XT is a little faster?). I'm running an optimized version XP on a Pentium 4 3.00GhZ. I suspect the bottleneck in this situation could have been the hard drive as well. My main drive is a regularly defragmented 250 gig, which according to specs runs at a maximum of 7200 rpm, but my mobo only supports S-ata1 speeds.

Currently I don't seem to have issues with replaying/ skipping through more compressed huffyuv, but by checking what the system requirements for decompression are, I'd like to exclude the risk of ending up with a collection that needs to be reencoded entirely in order to be played back on my current system.

In addition I wondered if the ffdshow codec of huffyuv isn't a little faster for decompression than the original (2.1.1)? Which would be wiser to stick with?

Last edited by Kereellis; 02-12-2010 at 02:08 AM.
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  #2  
02-12-2010, 06:37 AM
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I went ahead and moved this to a new thread, since it's starting a new topic.

Quote:
Originally Posted by Kereellis View Post
Hello again dear experts
Since I kept stumbling on difficulties to find properly working hardware, I've decided to let most of my homevideo tapes (the real precious ones) get ripped by a professional (although that doesn't mean I haven't learned a lot of useful stuff here that has helped in deciding on how I'd like to get it done, which proved useful in selecting a pro).
Video is definitely not an easy task.

The main goal of this site is for advertising our media services. While we share knowledge in various ways (guides, forum posts, etc), we do actually hope that many folks will use this information as a guide for selecting a proper service (us, hopefully -- or at least somebody like us) to help them with their projects.

For some folks, this means picking a service that does everything -- from recording, to editing, to distribution. For others, they just need piecemeal services. Your desire to get the video captured as HuffYUV is a perfect example. That's all you need help with -- capturing. (At least, that's all you need help with right now!)

Quote:
get ripped by a professional
I just want to nitpick this real quick. "Rip" is an amateur word, often used incorrectly (as it is here). While it's understandable that you might use it, RUN AWAY QUICKLY from any so-called "service" that uses it. This is a clear indicator of hobby-quality work and lack of advanced understanding of video.

Quote:
In terms of analogue equipment, this guy seems to be the best choice there is available around here,
Most professional video services work from closed facilities, and many of them only deal in private contracts. There is no walk-in location in a strip mall, and phone numbers have slowly gone unpublished due to time-wasters and telemarketing junk calls. While we've heavily shifted to contracts in the past few years, we're still committed to helping the mom-and-pop home/hobby/amateur crowd. You guys need services, too! And the "local options" are often pretty terrible.

The "local option" is typically not the best one. Not to say all walk-in locations are bad, but many are pathetic. Many more bulk-ship tapes to unspecified locations overseas! Yikes!

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since he has been passionately collecting and maintaining high end equipment (video brackets, tbc's etc.) for decades.
Old gear and gear-head collecting honestly doesn't mean much. Be sure there is knowledge, experience, and quality-of-work to back that up.

Quote:
Besides that, he's also the only pro I could find who didn't object when I asked him to rip to harddisk in such and such a way as I'd have done it myself.
Pathetic, isn't it? Some of these people don't understand that DVD-Video isn't the only digital format.

Quote:
Most people offering their services in the field of digitalization sadly have proven to be either amateurs that like to make some easy money off their dvd recorders, or a few that stick to their own theories and methods and get touchy if you make a request that strays from that.
YES! YES! YOU SEE THE LIGHT! We've stopped competing with $6.95 per tape conversions or "fill a box for $19.95" services. Our services are now bombarded by "can you fix this bad conversion I got from the $6.95 place?" work. The prices are ridiculous, set by people that fail to understand the technicals of video, hoping to get rich off a room of DVD recorders.

The reason many of those folks get touchy is because they don't know what the hell they're doing.

Quote:
Anyway, for my reassurance I'd just like to check a few facts here (it'll be quite pricey after all) .
Pricey? Maybe see what our rates would be on it?

Quote:
1. As a capture device this particular digitalizer uses a Datavideo DAC-10. Since I'd like him to rip in huffyuv, I'd like to make sure it isn't one of those devices that hardware-compresses to dv-avi forehand. In addition it would be nice to make sure if it's known to be 'accurate' enough.
The DAC-10/100/200 are DV devices only. That's it, period. Nothing else. The only way to get HuffYUV is to convert the DV (either post-capture or on-the-fly during capture).

The only people who pretend these devices are "professional grade" are the companies selling them. I like Canopus and DataVideo products, but when it comes to their DV converter boxes, they are all bark (marketing) and no bite. I never see these in studios or real high-quality conversion facilities, only in the hands of home users and students.

Sometimes you'll see these in film conversion services -- amateur home films, that is, the 8mm's grandpa shot in 1950 -- but it's really the only option to conveniently return quality film work. (It's too shaky for DVD conversion, in most cases, to be an "archival grade" solution.) Color on home film tends to be crap anyway, so DV colorspace compression loss is transparent.

The same argument could be made for VHS sources, but color values tend to be better, and there is less inherent shake frame-to-frame. DVD-Video and uncompressed are better solutions.

Tape is officially dead now too -- everything has moved to disc, drive or solid-state. Nobody likes "eaten" tapes, be it VHS or DV. DV is a decade+ old technology, and it's been escorted out the door by H.264 (for better or worse) and HDV.

Quote:
I also read the DAC-10 comes with an 'audio lock' function, but I'm not sure how those work. Perhaps by dropping/inserting frames or dynamically resampling audio like vdub? (For editing purposes I'd like to know if I'll end up with audio that's already resampled, if it'll be possible to tell).
"Audio lock" is a gimmick. It's an invented term (mostly used by Canopus for their DV products) and doesn't mean anything. It's a marketing buzz word. Maybe 10+ years ago, when a Pentium III computer used a slow IDE hard drive and audio/video capturing was still in it's infancy, yes a/v sync lock was a problem. But now? 2010? No way. A cheap capture card in a budget dual-core tends to be able to maintain a/v lock just fine, without any extra advertised feature. Dropped frames and a/v sync has become less and less of any issue in the past 5-10 years (for standard-def video work), due to advances in computer components.

Quote:
2. Should I ask him if he monitors the tapes as he rips them?
Yes!!!! An unmonitored video tape can easily turn into "I'm sorry, the VCR ate your tape while I wasn't looking."

Quote:
From how he said he'd rely on either automatic time/size limits for the files or rip the tapes as a whole, I got the impression he may not.
He hits play on the VCR, record on the computer, and ignores it. Welcome to batch processing, where your tapes don't matter to the service.

Quote:
For a higher tariff, he does use high end equipment that can correct chroma and luminance errors, but I'm not sure if they require manual operation.
No. His "high end equipment" is probably just an embedded TBC in a VCR. Which begs the question: What crappy non-TBC VCR does he use for this "professional service" when not paying for "high end equipment" use?

Quote:
I'm personally just used to basic proc.amp settings (brightness, contrast and such) that often need adjustment in order to optimize the different types of recordings on these compilation tapes of homevideos (which is mostly required due to the difference between inside/outside recordings, and a few tapes that contain recordings from two different camera sources, that each had their own quirks).
This is time-consuming, but can be done. It would cost extra anywhere that offers it.

Quote:
I also don't feel like paying extra for the optimization of one type of recording that is detrimental for others on a tape.
Again, very time consuming. To properly correct a "mix tape" you have to capture it in many separate pieces, each with it's own optimized settings and tweaks. There's nothing more miserable than a tape where somebody records 5 minutes at a time for the entire 1-2 hours worth of tape. That's a $100 tape if you have to correct everything.

Quote:
3. What kind of system would theoretically suffice for playing more compressed huffyuv files? I intend to request rips compressed with the settings predict gradient or preferably even median, but I've experienced a slower playback of such files once before due to unknown causes (with my currently installed ATI AIW 9800 PRO that is, perhaps the 9600XT is a little faster?). I'm running an optimized version XP on a Pentium 4 3.00GhZ. I suspect the bottleneck in this situation could have been the hard drive as well. My main drive is a regularly defragmented 250 gig, which according to specs runs at a maximum of 7200 rpm, but my mobo only supports S-ata1 speeds.
This isn't a really good playback format. But that said, this system I'm typing on right now is a 2.8Ghz, IDE 7200rpm, and HuffYUV plays back fine. Any problem with playback may be one of not having a second hard drive dedicated to video. The OS drive sometimes does not play nice with streamed video content (local streams).

Quote:
Currently I don't seem to have issues with replaying/ skipping through more compressed huffyuv, but by checking what the system requirements for decompression are, I'd like to exclude the risk of ending up with a collection that needs to be reencoded entirely in order to be played back on my current system.
As noted above, probably won't be an issue. Use VLC, GOM -- anything other than Windows Media Player. Sometimes HuffYUV conflicts with other system codecs, but only for playback. I don't know the exact combo. I have issues on a few systems here, but I don't often have need for playback -- most everything is scrubbed in an editor anyway.

Quote:
In addition I wondered if the ffdshow codec of huffyuv isn't a little faster for decompression than the original (2.1.1)? Which would be wiser to stick with?
Don't use HuffYUV MT (multi-threaded) if you want good playback. It processes faster both in and out, but it plays like a beast (or not at all).Just stick to standard HuffYUV codec, and that's it.

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  #3  
02-12-2010, 06:49 AM
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By the way if I come across aggressive on this topic, it's because I've declared war on myth and stupidity, as it relates to this field. I've had enough. Consider this my resolution for 2010. Competing with fools has become tiresome. Rather than just point out why we're the service you should use (or a few of our peers with good service, too!), we've started to point out the services you should avoid at all cost.

For example, a recent post at http://www.digitalfaq.com/forum/show...67&postcount=7 -- idiots.

I feel sorry for folks who get duped by the hacks and quacks.

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  #4  
02-12-2010, 04:21 PM
Kereellis Kereellis is offline
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Quote:
I just want to nitpick this real quick. "Rip" is an amateur word, often used incorrectly (as it is here).
Well.. that's my own phrasing. I'm Dutch, I'm an amateur. I sometimes use the word rip because it's short and people know what you mean anyway (right?). He has used the words transfer and restore for describing his service.

Quote:
Most professional video services work from closed facilities, and many of them only deal in private contracts. There is no walk-in location in a strip mall, and phone numbers have slowly gone unpublished due to time-wasters and telemarketing junk calls. While we've heavily shifted to contracts in the past few years, we're still committed to helping the mom-and-pop home/hobby/amateur crowd. You guys need services, too! And the "local options" are often pretty terrible.
I should make it clear that this guy isn't a competitor for your service. By local I mean within The Netherlands. Just trust me when I say this country is extremely primitive on the matter of digitalizing video. Practically everyone just lets their old stuff get transferred to dvd by stores and most individuals who claim to be pros just offer the same service as well. If I had the option of letting it done by you guys I'd have gone with that long ago, but alas I don't feel comfortable with sending my tapes and harddisks back and forth across the ocean. There aren't any similar services to yours here either. This guy does come close (in terms of analogue correction), since he has come across as serious about what he's doing and he doesn't just work for the mom and pop-crowd either but attracts international customers as well. He also told me that because of his reputation he doesn't need to advertise. It seems true that he doesn't. From his site and our phone calls I could tell he is fanatic and specialized in the analogue end of equipment (he also offered me to show his equipment in use). However myths about digital formats are vastly alive here, and even people like him will try to tell me that the dv-fromat suffices for VHS. As an exception to others I've contacted he said to be willing to work with huffyuv for this project. It's just that his DAC-10 doesn't seem to allow the capture of genuine huffyuv video, much to my grief. I'll suggest to him the use of my easycap (yes). This is practically my only option, aside from doing it myself with the help of a 11 years old Sharp vhs-player and said easycap. Since I started out with this project in May last year, I've invested more than enough time and money in non-functionable if not plain untraceable hardware and I'm seriously sick of it. I'm lucky to have found some of the best advisors in the world in you guys, but I'm cursed when it comes to the means to work with your advice. I hope you guys understand that. It's not like I'm easily 'tricked' by quacks in my ignorance. On the contrary. My knowledge renders it impossible to get this job done in a way that meets my standards.

In any case, I've asked this guy whether he monitors the tapes. If he'll reply he doesn't, I'll admittedly get suspicious and maybe I'll just let him do one or two tapes first to see how much better the results are than those following from my own attempts.

Quote:
Don't use HuffYUV MT (multi-threaded) if you want good playback.
Hmm, I haven't heard of that one. In direct show there are two options under the FOURCC item: HFYU and FFVH. HFYU is set per default, and it worked fine for me (but it does require the directshow codec for playback). It's also possible to select 'adaptive huffman tables', but that sounds like it would compress too much for flexible playback.

The reason I'd like to try out the predict median setting is that I have over 46 hours of material, and I'd like to see all of that backupped on an extra drive as well. At 50 gigs an hour I have enough space for that, at 70 I don't. In any case, I'll run some tests with it since my system should be able to handle it. Thanks.
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02-12-2010, 04:38 PM
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HuffYUV generally runs at 30-40GB/hour -- I've never seen it go to 50-70. I mean, 75-80GB/hour is uncompressed YUY2/4:2:2!!
HuffYUV MT runs about 10% larger, but encodes about 50% faster on multi-core.

PAL DV isn't as abusive to colorspace compression as it is in NTSC. Give him a tape to try, and see how it goes. It may turn out fine for you.

DV is also 13GB/hour, and will still play fine on your computer.

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  #6  
02-12-2010, 07:39 PM
Kereellis Kereellis is offline
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Yes, damn.. it suddenly hit me that I got uncompressed YUY2 and huffyuv mixed up all this time. This seems to be because huffyuv supports YUY2, plus the terms losless and uncompressed are tempting to mix up, but now all these little inconsistencies I came across (file size etc.) finally make sense.

Concerning the losless aspect, since I apparently got mostly YUY2-captures I wondered if it's worth comparing these with their respective huffyuv reencodes, or shouldn't there be any differences upon decompression/playback (as the term losless suggests)? Like, can huffyuv compression be compared to compressing to zip-files without truly losing any data? (In the case of YUY2-> compressed YUY2, not RGB-> YUY2 I mean).

I guess I'll talk the matter of the dv-format over with this guy when I go visit him. Who knows, so far he has presented himself as pretty well-willing, so perhaps he'd be interested in learning of the differences between huffyuv/dv-avi himself. In any case, a try-out tape indeed seems to be a good idea before I hand over the entire collection.
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02-13-2010, 08:35 AM
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Quote:
Originally Posted by Kereellis View Post
can huffyuv compression be compared to compressing to zip-files without truly losing any data?
It is actually the very same type of compression! Both are based on Huffman coding. If you want to read all the math on how it works, check out the wiki article: http://en.wikipedia.org/wiki/Huffman_coding. Also, HuffYUV is actually working in YCrCB colorspace, too, not YUV. But technicals asides, they're essentially the same.

from wikipedia:
Quote:
Huffyuv (or HuffYUV) is a lossless video codec created by Ben Rudiak-Gould which is meant to replace uncompressed YCbCr as a video capture format. Despite the "YUV" in the name, it does not compress the YUV color space, but YCbCr. "Lossless" means that the output from the decompressor is bit-for-bit identical with the original input to the compressor, given that no color space conversion takes place. Huffyuv's algorithm is similar to that of lossless JPEG, in that it predicts each sample and then Huffman-encodes the error.
I think the JPEG comparison is not the best one to make here. MPEG is more like JPEG than is a lossless algorithm. There is loss in a JPEG and in an MPEG, although visual effects can be mitigated (often by psychovisual methods). I'd say HuffYUV is more like a compressed TIFF, which also used Huffman style coding. Not sure if you're familiar with TIF images -- they've largely been discontinued, because HQ JPEG files can look just as good, at smaller sizes, thus easier to work with.

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Originally Posted by Kereellis View Post
so perhaps he'd be interested in learning of the differences between huffyuv/dv-avi himself.
I get squeamish when a pro service doesn't know the basics. I'd hope this guy knows the difference between 5:1 DV compression and the lossless compressions!

With 5:1 DV compression, you can still get blocks and digital artifacts during motion. It doesn't really happen when DV is used for shooting video, but it does when used as a conversion format.

DV was never really meant as a capturing/tape-conversion format, it was developed as a replacement for VHS/S-VHS and 8mm/Hi8, but with quality approaching closer to Betacam SP used by camera crews. (But DV was not as good as Betacam, which led to DVCPro.)

The 5:1 compression was partly an issue of tape size, tape speed (physics limitations), and keeping at least an hour or more of shooting per tape. There was also concern about editing it on home computers, so file size and bandwidth was kept down to available speeds of the time, being 5400/7200rpm IDE hard drives and Firewire connections (both very new at the time!) Again, DV was new tech in the age of Pentium III computers in the mid/late 90s.

DV is not much different from I-frame MPEG, both being intra-frame encoding methods. (GOP MPEG encodes temporally, interframe, as used on DVD-Video and broadcasting. These are often referred to as "Long GOP" formats.) Temporal = time, FYI. In a 30fps DVD video, a GOP is often 15 frames, so you have 2 GOPs per second. Broadcasters use much longer GOPs, sometimes 100-300frames! So your compression can be spread out across quite a few seconds.

DV is prone to color problems and blocks, even during shooting. When used for compression, it tends to magnify these issues. It doesn't help that you can critically compare the before/after tape, unlike real-life shooting.

Color problems are mostly due to colorspace compression, using 4:1:1 NTSC (180 samples per line) or 4:2:0 PAL (co-sited 360 sample, alternating lines). Remember that DVD-Video is 4:2:0 NTSC or PAL. While the samples alternate lines, having more of them spread evenly helps retain color fidelity. The common defense to DV is that DV exceeds the color bandwidth of the source, thereby justifying the lower sample count, but I find that to be more theoretical than anything else. In practice, VHS>DV often looks "cooked" compared to the tape, both in contrast and in edge accuracy of colors.

Related rant: To further compound problems, some people like cooked video, because it has "bright picture" and "better colors". There's not a cure for stupid, sadly. This is one reason HDTV sets are such a mess, with people wanting the overly-bright and abused image quality, while accurate models go unsold. The goal should still be accuracy! If somebody wants to watch it in butchered form, then they can crank up brightness, contrast and saturation on their TV set. Once the video is cooked, you can't undo it, you're stuck with it.

If you want to read more on DV colorspace technicals, Adam Wilt has written about it --- from a shooting and editing/processing aspect !! --- at http://www.adamwilt.com/DV-FAQ-tech.html#colorSampling -- I don't necessarily agree that 4:2:0 is horrible for the capturing/tape-conversion, I think it's better than the 4:1:1 alternative.

Another look at colorspace is in a wiki article: http://en.wikipedia.org/wiki/Chroma_subsampling
I don't know how credible that article's sources are, so don't examine it too closely. I mostly link to it so you can look at the sample images.

Given the choice of formats, I'd much rather have:
  1. HuffYUV lossless
  2. MPEG-2 I-frame or short-GOP
  3. uncompressed YUV / YUY2
DV doesn't even make the list. It's sort of like licorice jelly beans or coffee ice cream -- something you tend to eat when all the others are unavailable. I begrudgingly accept DV when other options are exhausted.

I would admit that I dislike MJPEG (Motion JPEG, not to be confused with MPEG) more and more. I'd probably pick DV over MJPEG. It's not so much the MJPEG format, but rather the poorer quality of MJPEG codecs found in 2010.

Here's a good colorspace chart from http://www.dvcentral.org/DV-Beta.html

Image1.gif

That shows how the colorspace compression takes place.

And I didn't even go over the variances in DV, between the different codecs (Canopus, Matrox, Sony, Panasonic, etc).
Matrox is probably the best of the four I just listed.

Quote:
Originally Posted by Kereellis View Post
In any case, a try-out tape indeed seems to be a good idea before I hand over the entire collection
Yep, give one tape a try, see how it goes. The least important tape, of course.



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  #8  
02-14-2010, 07:21 PM
Kereellis Kereellis is offline
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Thanks for some of the arguments against the dv-format. Hopefully that guy will listen to them instead of sticking to the myths surrounding it.

Quote:
It is actually the very same type of compression! Both are based on Huffman coding. If you want to read all the math on how it works, check out the wiki article: http://en.wikipedia.org/wiki/Huffman_coding.
Well wiki pages are in general a bit too technical for me, but yea, I got an idea of how it worked from another source.

In spite of theory though, I have noticed something a little odd upon playback of a particular huffyuv-compressed YUY2-file. As it turns out it seems that it's slightly, but only very slightly more saturated than the original.

I basically made bmp-screenshots in MPC (directly, using 'save image as') of the same frame in the following ways:
- during playback of the original file (uncompressed YUY2)
- during playback of the huffyuv encoding (libavcodec in ffdshow)
- as above but with the standalone codec of MPC by disabling huffyuv in ffdshow
- during the playback of a directshow-encoded huffyuv version of the file

In every case where I used huffyuv, there was the subtle effect of more saturation (mostly in the red chroma noise). At first I thought my eyes were deceiving me, but by switching between screens while focussing on the image instead of the file name I was always able to pick out the one screen of the original YUY2 encoding among these four (like 8 out of 8 times).

However, after reencoding the huffyuv file to uncompressed in vdub, the screen of this frame turned out exactly the same as the original. So, now I'm curious, is it theoretically possible that during the playback of huffyuv the reproduction of images can be slightly inaccurate compared to the uncompressed video? All the same I could upload the screenshots if you'd like.
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  #9  
02-15-2010, 08:10 AM
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Colors will always vary slightly due to colorspace, encoder, decoder, matrices and viewing device. Playback on a computer often uses overlay graphics mode, which can differ from standard mode in an editor or preview mode.

I see things like this all the time -- I have to remember to adjust myself accordingly, when editing or restoring.

Test clips are always helpful, when in doubt.

Sure, post some sample screenshots, that always helps a conversation.

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  #10  
02-15-2010, 07:53 PM
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Alright, I very carefully cropped some screenshots in vdub so the coordinates of each pixel would match the ones in the screens taken in mpc, then resorted to photopaint to determine the RGB value of a single particular pixel in all significant screenshots (I assumed it doesn't matter that the colorspace is automatically converted to RGB here).

As it turned out my earlier observation wasn't incorrect. Huffyuv is played back with slightly more saturated colors than YUY2, but not just in MPC, in vdub as well according to these results.

I packed the screens I used for comparison and the results of the pixel test (that can be repeated since I included the coordinates as measured from the top left).

Visit this page for the tests.zip file. I also apologize for the randomness of the screen. At some point you just stop realizing what you're looking at.

The most significant result for me would be the one conducted on the screenshot from the reconverted capture (from huffyuv back to YUY2), since it implies the colors are the same compared to the original (which is also what the eye tests told me). Nevertheless, it's kind of odd that losless compression would after all produce a color difference upon decompression even without colorspace conversion taking place simply because the compressed data is handled differently.
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02-16-2010, 04:20 AM
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NOTE: Try to upload images/attachments directly into the forum. Instructions at: http://www.digitalfaq.com/forum/show...ages-1529.html.
Also don't use BMPs, use PNG or JPEG images, and then put them in an inline preview as shown in the attachment instructions.

I've attached the last group of images for you:

0746-Huffyuv-(fast-recompress;-mpc).jpg (43.4 KB)
0746-Huffyuv-(fast-recompress;-mpc).jpg

0746-Huffyuv-(vdub).jpg (43.4 KB)
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0746-yuy2-(mpc).jpg (43.3 KB)
0746-Huffyuv-(vdub).jpg

0746-yuy2-(reconverted-from-huffyuv-mpc).jpg (43.3 KB)
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0746-yuy-vdub.jpg (43.5 KB)
0746-yuy2-(mpc).jpg

And your TXT notes:
Quote:
pixel coordinates: X=251,Y=151
YUY2 in mpc - rgb: 54 32 46
YUY2 reconverted from huffyuv in mpc - 54 32 46
YUY2 in vdub - 55 33 47
huffyuv in mpc - 55 32 47
huffyuv in vdub - 55 32 47
Honestly, I don't see much difference here, and I have a calibrated monitor. Maybe if you pump up contrast and saturation on your computer monitor, then there may be more visible differences for whatever reason (decoder, overlay, etc). But that's really not the way it should be viewed.

What I do see a lot of, however, is chroma noise -- all those color specs.
Read more about chroma noise at http://www.digitalfaq.com/forum/show...flaws-565.html



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02-16-2010, 09:50 AM
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Hmm it's just that the RGB-values returned by Corel photoshop confirmed exactly what I thought I was seeing (my brightness and contrast settings are quite low btw). I'm not saying these differences cause visible annoyances (especially NOT with increased brightness! I couldn't even bare look at a bright monitor that intently), but that there is a subtle difference in how yuy2 and huffyuv are displayed even when viewed in virtualdub, and that the difference lies in color saturation. That's it, but it's still weird! (And perhaps also the fact that I could make out any difference while expecting there wasn't any.. I admit that I had to look very carefully though).

Yes I'm quire aware of the flaws in these vids. I have a S-VHS player with DNR actually, but that one adds an annoying buzz to the sound output. Tried to remove it in software and by using different cables and what not, but to no avail. Cleaning the audio head didn't help a thing either.

This is why I wanted to pass these tapes to a pro. I can only seem to get my hands on flawed equipment and it's starting to cost me more this way ;\

Last edited by Kereellis; 02-16-2010 at 09:54 AM.
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02-16-2010, 01:49 PM
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Quote:
Originally Posted by Kereellis View Post
. I have a S-VHS player with DNR actually, but that one adds an annoying buzz to the sound output. Tried to remove it in software and by using different cables and what not, but to no avail. Cleaning the audio head didn't help a thing either.
Capture it twice!
Once with DNR turned on, for the video.
Once with DNR turned off, for the audio.

Overlay them in an editor (I use Adobe Premiere for this, when AVI) to sync within a half-frame radius.

Or for MPEG, trim the lengths of both to match exactly, using an MPEG editor like Womble MPEG-VCR or Womble MPEG Video Wizard.

I've been in similar situations.

Going back to the variances you measured, being off by one value may be a difference of some other kind.

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