Improve playback quality of captured VHS tapes? + computer preview output

[Kereellis]

Hello again

For quite a while now I've been capturing PAL vhs-video in YUY2/huffyuv with the following hardware setup:

JVC s7950 -> 1t-tbc -> ATI Radeon 9600XT

Captured in 720x576. I left the video interlaced.

However, even though this would be a recommended workflow, if I play back any captured file on my analogue widescreen, I notice the image still looks far less good/sharp/'natural' than when I directly connect the vcr to the tv using Mediaplayer classic-> ATI (admittedly, composite, but this shouldn't make that much of a difference) -> widescreen. Is there a way to compensate for this unauthentic look at any point between capturing and playback? For instance, will the issue be solved once I switch to a digital tv-set / HDMI input, or do I need to upscale/deinterlace somewhere in the progress?

I'm guessing the reason for a more cooked image would be, that the tv simply handles the 'raw' analogue video nicer than the analog signal of the digitalized video when it comes to rescaling, contrast adjustment and deinterlacing of the image, or maybe the ATI just isn't the best output device. However, even if this is the case, I'm pretty much in the dark as to how to tackle this problem, so I'm eager to hear any suggestions.

[juhok]

I didn't quite understand how you're routing the signal in different scenarios. But analog is analog, there's no different kinds of "raw" and "less raw" analogs. The signal from VCR is likely more unstable than from PC card and benefits from TBC(frame sync). Shouldn't be any difference in the "look" of the image that could be atributed to that (edit: capture in/output quality being different subject).

Then again, when I got 1T-TBC I never used it because of all the artifacts / problems it added to image.

There is no significant difference in my setup in:

VCR -> monitor
VCR -> TBC -> PC -> Monitor (routing without capturing)
PC -> monitor (playing back after capturing)

[juhok]

To be more clear by "monitor" I meant analog CRT video monitor.

[Kereellis]

I see my words were switched around a bit, indeed rendering my question confusing.

I was talking about the full screen playback of digital captured material on a widescreen tv-set (so I'm not assuming the existance of anything "semi-analogue" here, there's just a digitalized analogue video, reconverted to an analogue signal by the videocard).

Thus the playback set-ups are as follows:
captured YUY2 file on PC (mediaplayer classic) -> ATI composite-> widescreen analogue tv

versus:
same video on tape in JVC s7950 -> same tv

There's a significant difference in visual quality between tape playback and capture playback on tv, although it's hard to describe exactly the nature of this difference. In all the digitalized video on tv just looks less sharp and less vibrant, although I've been using default settings and a recommended capture device (I didn't get better results with a tbc-1000 I once had either).

I know the tbc reduces the image quality somewhat (on a very small scale, but it's the sort of quirk I've come to accept because the ATI is too sensitive to do without), but I don't think it's the crucial factor here. I've run tests without it too once, and the issue described has always been present.

I hope that cleared things up

[admin]

Computer output is progressive, so it will always appear softer on interlaced displays. You've have to create a format made for an interlaced display, like MPEG-2 for DVD, in order to see the true sharpness of the image.

The flaw comes with the preview method, not the formats.

I never use the ATI output to TV for judgments on sharpness -- only on color clarity, overscan boundaries, etc. You'll want to judge the sharpness on the computer's LCD or whatever type of monitor you're using (if you're one of the two people in the world that still use a CRT, aside from my mom).

Quote:

But analog is analog, there's no different kinds of "raw" and "less raw" analogs.

Well, yes and no. There is 16-bit, 24-bit, 32-bit -- and then 4:2:2 vs 4:4:4, etc. There are variations on what "uncompressed" can mean, in various contexts. For most conversations at this site, 4:2:2 and 24-bit counts as uncompressed video, as the topic is largely consumer formats (VHS, 8mm, etc) and lower-end pro formats (S-VHS, Betacam, etc). Some of those don't get to be important until you're shooting your own cinema-grade video, or working with broadcast workflows.

[juhok]

I've never used ATI Radeon 9600XT but I'm quite sure that it's analog input / output is not up-to-spec and this is causing the variation in perceived image quality. All modern(and old) consumer videocards I've seen are more or less bad in this regard. By switching composite analog output to HDMI connection you'll eliminate (bad) DA conversion in your ATI and another AD conversion in your TV which might aswell be sub-optimal quality. What is bad is of course subjective and my standards are quite high.

Quote:

Originally Posted by admin

You'll want to judge the sharpness on the computer's LCD or whatever type of monitor you're using (if you're one of the two people in the world that still use a CRT, aside from my mom).

I'm using CRT video monitor (not CRT TV) to monitor all my work, beside LCD screen.

[juhok]

Quote:

Originally Posted by admin

Well, yes and no. There is 16-bit, 24-bit, 32-bit -- and then 4:2:2 vs 4:4:4, etc. There are variations on what "uncompressed" can mean, in various contexts. For most conversations at this site, 4:2:2 and 24-bit counts as uncompressed video, as the topic is largely consumer formats (VHS, 8mm, etc) and lower-end pro formats (S-VHS, Betacam, etc). Some of those don't get to be important until you're shooting your own cinema-grade video, or working with broadcast workflows.

When the signal is converted to analog there is no more 4:2:2 or 4:2:0 as such. But I get your point. What I meant was that there's no special kind of analog that comes from VCR, compared to other sources (say broadcast quality PC card). With TBC's and other post processing in deck, and external frame syncs, the signal has seen a lot of AD/DA action before even hitting the capture card. It would make sense to get the digital signal off TBC/frame sync before converting back to analog. There are TBC/FS's with SDI output but I don't have that kind of money

[Kereellis]

Quote:

Computer output is progressive, so it will always appear softer on interlaced displays. You've have to create a format made for an interlaced display, like MPEG-2 for DVD, in order to see the true sharpness of the image.

The flaw comes with the preview method, not the formats.

Thanks, I mean, that sounds like a perfectly reassuring explanation for what I've been seeing I assume for this issue it doesn't matter then, that the video file itself is still interlaced because it is still put out by the ATI as a progressive signal?

And since my knowledge is pretty limited on this, is there a way to circumvent the need for mpeg2 conversion, for instance by upgrading to an lcd screen / hmdi wiring (which is what I think Juhok suggested as well)?

Juhok also makes an interesting point about the AD conversion itself. I haven't been recommended anything beyond my current set-up, but since I have a newer pc (without AGP support) as well as some hundreds to throw around, I've considered the purchase of an additional capture device lately. Currently I'm considering the Matrox MXO2 Mini for PC (as a possibly more reliable alternative to the Blackmagic Intensity Pro I had considered earlier) and would like to know what you guys think.

Now with my ATI there are a few points where I hope such a device would bring improvements:

1) Apparent sensititive circuitry requires the 1t-tbc to be in use for all tapes, and the tbc not being a high-end device, it does add some 'textures' to the image, which compromises the otherwise decent capture quality of the card. In all honesty, it seems to me to be certain that the ATI is overly sensitive to signal instability (and so is my other ATI, so it must be an inherent thing), because even my Easycap can capture most tapes pretty well tbc-lessly without constantly dropping/inserting frames.

2) It's AGP-based and therefore requires my old pc to occupy space in my room for a long while to come..

3) The tbc-less capture quality seems relatively good, and the textures are smooth instead of pixellated, but even so, I can imagine there's still room for improvement in image quality. However, I'd like to know if recent devices in the price range of the MXO2 Mini actually implement such improvements, besides having future-oriented advantages such as HD capture features.

Anyway, I appreciate the assistance so far. Oh, and I'm sorry my topics always seem to expand into broader questions like this.

[juhok]

I don't know about MXO2 Mini, but I'm confident that Blackmagic does not work well with your VCR without TBC/Framesync. What are your reliability concerns with Intensity? Pretty much all problems I've seen around are either related to lack of TBC/Framesync or user error. Not to say there cannot be any problems.

Why did you change your TBC-1000 to 1T-TBC? From my own experience and from your description 1T-TBC seem to distort the image beyond "normal operation", where TBC-1000 does no such thing for me.

[admin]

I'm of the understanding that the ATI card outputs a progressive signal. The TV will simply display the interlaced version, which is basically the same image over both fields. Remember that any interlaced input is deinterlaced for on-screen (computer) preview by the ATI card -- possibly with framerate doubling, but more likely with bob/weave combo used by the Theatre 100/200 chipsets. And this is the same sort of "preview" that is output to the TV, based on my observations. I really don't know all the specifics of how each piece of the card's hardware operates. It really doesn't matter, anyway -- the point is simply that the signal is processed several times, and is different from the source input or the files it has recorded. The ATI AIW card was never intended to be a "preview mode" in this way. This is where you'll have to remember that the ATI All In Wonder cards were created for a consumer audience, even if certain functions (like AVI and MPEG capturing) were of a professional quality.

The best preview is to copy the files to another dedicated viewing device. MPEG-2 DVD-Video is convenient for a DVD player, but any number of "media players" work well these days, such as the WDTV boxes. These can play any number of formats. How accurately these work, I don't much know, as I have never used them for this specific purpose.

But again, this is really only a requirement if you're trying to ascertain the sharpness. The ATI preview works fine for color tweaking. I would ask what the need for such a preview is. The input formats all have a finite level of detail, and there's not much you can do to change this anyway. What I do is split the output to both a TV set and the ATI card at the same time, with s-video to the ATI and composite to the TV. Thus I can see any pre-capture changes being done in hardware.

The Blackmagic has, to my knowledge, a professional output mode made for such things, whereas the ATI did not. However, you'll be hard pressed to replace the recording functionality of an ATI AIW card with anything currently available on the market. What you're doing now will be almost completely abandoned for new methods. Newer doesn't mean better.

Regardless of video capture card, you need timebase correction. Analog video is too messy signal-wise for a quality digital acquisition or "capture" of that video input. If that TBC is causing problems, then get another one. Many of those old broadcast grade TBCs were created with other tasks in mind -- not VHS to DVD/digital conversions. The AVT/CTB and DataVideo lines, however, were. Maybe you need to simply swap over to an AVT-8710 or CTB-100? More on TBCs at the post "What is a TBC? Time Base Correction for Videotapes."

[Kereellis]

I had a bad experience with a tbc-1000 that pixellized the image horribly, which it probably did because it was broken but it still left a bad taste. Also, these were hard to get by (at least over here), so I switched to an alternative. As for the 1t-tbc, I'm talking of changes on a rather small scale that aren't visible without enlarging screenshots (but of course replay on a tv-set would imply enlargement as well). Furthermore, the extend to which tbc's compromise image quality vary unit per unit, or so I've learned from around here. You can see why it seemed so tiresome to go out of my way and track down another tbc-1000.

To be honest, I just came across quite a few topics where people were having issues with the Blackmagic, and myself I've not been able to do anything productive with the Shuttle (but then again, who has..). Also, it seems that Matrox has more experience in producing professional capture devices. Of course the price tag is a quite a bit higher, so it's not like the Blackmagic is out of the question yet, unless it's as sensitive as the ATI after all.

With the easycap (which I use for 'audio version' captures) I only get frame inserts when there's a notable disruption in the signal (for instance between camera shots), while the Asus can't go about capturing without inserting at least a frame every 30 seconds without the tbc. I don't mind desynchronization all that much upon capture, but even so, all those frames are a pain to edit out later.

[juhok]

TBC-100/TBC-1000 can be got from amazon etc. I bought new 1T-TBC from the manufacturer and in certain sources it produced very noticeable "grid" in the image. Their support, which was advertised "the best in industry", didn't even once reply to my emails. Glad if works better for you.

About Shuttle, if I recall correctly it's USB3 version of Intensity and so far only works with certain chipsets, X58 or something. This is from BM support forums I've read at creativecow. This known issue is unrelated to Intensity. If it comes to getting new device maybe buy from somewhere that accepts returns in case of problems?

[Kereellis]

Quote:

Maybe you need to simply swap over to an AVT-8710 or CTB-100?

I'd like to, but I thought the 1t-tbc was pretty much a repackaged AVT-8710? And when picking a tbc, I learned there are good and bad experiences with practically all models. I'm not saying mine is doing a bad job, it's just that for image quality rather than stability, not using one would seem to be preferable.

Of course I don't have much to compare my 1t-tbc to, but I could see if I can find screens, so you guys can judge whether it's influence is abnormal.

Quote:

I would ask what the need for such a preview is.

Sorry to be unclear about that. Actually, it's not intended as a preview at all. I just would like to be able to enjoy my captured material straight from hdd, since I'd prefer my workflow to end at the huffyuv files. If a mediaplayer can output files sharply, can't a blackmagic or Matrox MXO2 do it properly too?

[juhok]

Quote:

Originally Posted by Kereellis

If a mediaplayer can output files sharply, can't a blackmagic or Matrox MXO2 do it properly too?

If Intensity doesn't have some radical changes from it's "big brother", I'd say yes - they should do it properly. If not, return them to the seller.

[admin]

The 1T-TBC looks like a different device entirely. It doesn't appear to be the AVT-8710 / CTB-100, no. Maybe there's something I'm not seeing here, but those don't appear to be the same device. The only real problem of the AVT-8710/CTB-100 is heat -- you can't run it 24/7 without some cool-down time every 5-6 hours. The case is plastic, and the internals lack heatsinks.

[jmac698]

Hi,
I only have a little bit to add here. When I last used a real TBC, it looked horrible compared to the VCR on pause. This was in a studio with UMatic tape. The reason was, the TBC only recorded 352x480 pixels. This should be enough to capture all quality, but it still looked quite pixelatted on an analog monitor.
Second, all composite outputs are interlaced, even if it cames from the video out of a video card. What might be happening is that MPC is bob-deinterlacing the video which will end up displaying at blurry. It could also be a mismatch in field order somewhere, which again will make it blurry or chunky.
I've managed to play video fine from computer through a Sigma Designs DVD accelerator card. Of course, we don't have these anymore. Another problem with video out is scaling. There's a program to fix this, TVTool. It's probably out of date now, but it would program the video encoder chip of the video card directly to give better video quality.
http://ixbtlabs.com/articles2/gf4/geforce4-tv-out.html

With my recent experience in video out, scaling is still an issue, the goal being 1:1 pixel correspondence from your screen to TV out. That would mean your screen is limited to 720x480 resolution. You can barely run windows on that small a screen, so 'video mirror' feature is also used (twinview, etc.). The procamp settings being exactly neutral is also a problem.
All in all, it's better to preview from a standalone device with a fixed output.

[Kereellis]

Quote:

Second, all composite outputs are interlaced, even if it cames from the video out of a video card. What might be happening is that MPC is bob-deinterlacing the video which will end up displaying at blurry.

On the tft it's still interlaced during playback. In fact I haven't even succeeded in deinterlacing YUY2 content through ffdshow when I tried to, and as far as I know MPC supports deinterlacing only for a select number of formats such as MPEG2. I'm also sure the 1t-tbc doesn't half the resolution. There just isn't a notable difference between capturing with or without it in terms of detail.

[admin]

Quote:

Second, all composite outputs are interlaced

Before it gets there, however, I'm pretty sure the ATI card has fed it a deinterlaced signal, because the graphics card can only generate progressive display. The conversion to interlaced composite would happen after processing. I maybe wasn't as clear as I needed to be the time in explaining that.

Quote:

the TBC only recorded 352x480 pixels

Strange. I've never seen a TBC that wasn't Full D1 (720x480).

Quote:

the goal being 1:1 pixel correspondence from your screen to TV out

Part of the ATI output processing downscales the image to about 640x480 resolution, if I'm not mistaken. It's not a full Full D1 720x480. But at the same time, between all the processing, I'd say it was comparable to somewhere halfway between VHS and S-VHS tapes, in terms of detail and clarity. It's "good enough" for judging the color quality, but not so much the sharpness. Again, consumer card.

[jmac698]

From what I've read, the problem with the video card tv out was they accounted for overscan thus what was labelled as 640x400 for example was really 720x480 with pillarboxing. This was explained in the link I gave.
Anyhow it's all theoretically, I was thinking of running MPC myself and recording the output of my video card, to see what it's doing. So far we don't have any answers.
Bit busy right now.