I'm capturing from VHS using a Hauppauge USB-Live2 and AmarecTV, passing through a Panasonic DMR-ES10 on the way. Here are two consecutive frames of a random recording, either side of a cut:
[Attachment 51239 - Click to enlarge]
[Attachment 51240 - Click to enlarge]
(It's a promo - don't judge me.)
You'll notice there's an after-image of the younger lady in the second picture. What's going on here? It looks a bit like the chroma is somehow a frame behind the rest of the video, if that's even possible. I don't think it happens with every capture, although perhaps it's just not always noticeable, but it is quite common. I'm at a bit of a loss to know where to start, and really need to be talked through what could cause this. What have I done wrong? What do I need to do to put it right?
I've attached a very short sample below for you to examine (Ut codec) - all it's been through is a 'Direct stream copy' trim in VirtualDub. The clip contains two cuts, and the issue is evident on both.
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The chroma isn't behind the luma, it's temporally blended. Make sure you turn off the noise reduction filter in the ES10. And the VCR and capture device too (if they have one).
Looks like you need a VCR with line TBC to clean that line wiggle, also use S-Video and a S-VHS deck whenever possible especially when chroma problems arise. DNR ON in the VCR can cleanup some of that chroma noise.
Thanks very much for the replies.
I'm going to have to do some test captures, but I know for a fact that both the noise reduction and comb filter of the ES10 are off. Would I also be correct in saying that this is an issue that, if not fixed at the capture stage, there's no way to put it right later? I expect so.
Apologies for the (probably) newbie questions, but I'm trying to fully understand what's happening here.
[Attachment 51258 - Click to enlarge]
Here you see the U channel, as greyscale (after increased saturation to make the problem more visible), of four consecutive fields. Field 55 is just before the scene change. Field 56 is the first field after the scene change. You can see the heavy blending of field 55's chroma (especially obvious in the window in the background). At field 57 the blending is still there but lighter. Even at frame 58 you can see a tiny bit of the blending.
Would I also be correct in saying that this is an issue that, if not fixed at the capture stage, there's no way to put it right later? I expect so.
Hi Mr Chris. Are you able to capture this same clip using some of your other hardware that you used in the Blind Test thread?
I'm curious about the source of the luma AGC effect at the second scene change.
- My sister Ann's brother
Here we go, then - I'll try and go in as logical an order as possible, but it's still going to be a bit all over the place. Before I start, the following stay constant in all of the tests:
Capture device is a Hauppauge USB-Live2
Capturing software is AmaRecTV
Codec is Ut
Bearing in mind that the issue in question comes and goes, it stands to reason that none of the above are suspects in this case. What else can we eliminate early on? Well, let's see if the chroma blurring is burned into the recording on the tape itself. The 'rawest' capture I can do is from my Sharp VCMH704 consumer-level VHS player directly into the Hauppauge via composite (01chroma.avi in the attachments):
Sharp VCMH704 - [Scart|Composite] - Hauppauge
[Attachment 51536 - Click to enlarge]
That screenshot (and please do click on the screenshot - it's resized when embedded in the post, which doesn't present an accurate picture) is the first frame after the scene change. Ignoring all of the multiple other issues with that capture, there's no sign of any after-image to my eyes (the black vest top from the original post is my main point of reference). I'm satisfied that the tape itself is not to blame.
Let's now feed the same VHS machine through a Panasonic DMR-ES10 (02chroma.avi):
Sharp VCMH704 - [Scart] - PanaES10 - [S-video] - Hauppauge
[Attachment 51537 - Click to enlarge]
Your eyes are probably more sensitive to these issues than mine, but again, I see no sign of the chroma mess in this one, either. So do we agree that it's not the tape, and it's not the ES10?
But that's all been composite so far - let's see if S-video is the problem. Time to fire up my old SVHS machine (03chroma.avi):
Panasonic NV-HS1000 - [Scart] - PanaES10 - [S-video] - Hauppauge
[Attachment 51538 - Click to enlarge]
The NV-HS1000 is in passive mode there, with everything switched off apart from the TBC. No issue that I can see.
All of this leads me to conclude that the problem lies with my previously-unmentioned latest acquisition, a JVC HR-S9600. Here's a capture through my normal preferred chain (06chroma.avi):
JVC HR-S9600 (TBC on) - [S-video] - PanaES10 - [S-video] - Hauppauge
[Attachment 51539 - Click to enlarge]
I've done a lot of toggling of settings (and we may get in a tangle here, because the PAL version gives different names from the NTSC model) and also tried different cables and inputs/outputs, but nothing can shift that after-image. Is this a general problem with the HR-S9600, or is it just my unit? I'd be surprised if I'm the first person to notice this.
There is, however, one final vaguely interesting discovery. The following is a capture through a chain identical to the previous, but that one had the TBC on and this one has the TBC off (07chroma.avi):
JVC HR-S9600 (TBC off) - [S-video] - PanaES10 - [S-video] - Hauppauge
[Attachment 51540 - Click to enlarge]
You have to look a lot closer, but an after-image is still there. However, now I wonder whether that's luma we're seeing rather than chroma. Try opening the video in (say) VirtualDub and rocking back and forth between the two frames following either of the scene changes. It's more of a shadow than a colour artefact, isn't it? Or is it something else?
I have a feeling I'm stuck with this issue, which is particularly disappointing as my captures have otherwise never been so good. Any ideas? All thoughts and theories welcome.
I've read that (some?) JVC S-VHS decks switch the noise reduction function along with the TBC. Ie, you use neither or you use both. Your captures here appear to verify that claim. And yes, from #7 it looks like the noise reduction in the luma is never completely disabled.
video #7, Y, U, and V channels (top field on top, bottom field on bottom) all contrast stretched:
[Attachment 51548 - Click to enlarge]
AviSource("07chroma.avi") AssumeTFF() SeparateFields() StackVertical(SelectEven(), SelectOdd()) StackHorizontal(ColorYUV(cont_y=1000, off_y=-100, cont_u=-256, cont_v=-256), \ ColorYUV(cont_u=600, cont_v=600).UtoY(),\ ColorYUV(cont_u=600, cont_v=600).VtoY())
[Attachment 51553 - Click to enlarge]