Quantcast Editing using uncompressed RGB/YCbCr capture? - digitalFAQ Forum
  #1  
07-01-2019, 03:03 PM
Masogir Masogir is offline
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Question Setup:
This was all done using VirtualDub2. I captured a 2:24 long VHS segment using "Uncompressed RGB/YCbCr" that came out to 2.81GB. I then proceeded to edit out 3 frames from the beginning of the video to remove some minor noise and saved a new AVI using "Uncompressed RGB/YCbCr". The new file with the 3 frames removed came out to be 4.2GB (over 50% larger).

My Question
I did some research and it should of ticked "Fast recompress" instead of "Full processing mode"... but why would reprocessing an uncompressed format turn out to be 50% larger? I am so confused... Should I even be capturing my old VHS tapes with this format to begin with?

Potential Relevant Information
Storage and PC specs are not an issue in my case so capturing using lagarith or huffyuv is not necessary (unless there is a benefit I am not aware of). I have a beefy PC, SSD, plenty of storage space, etc...

I'm happy with the cheap hardware I'm using since the software can compensate for timing and other issues for later editing/deinterlacing/etc... Right now I'm just trying to capture RAW video for later archives/edits and I'm just so confused on this one issue. Why does reprocessing under the same (uncompressed) format create a 50% larger file size?

Capture AVI Setup
Software: VirtualDub2
Capture Hardware: "VHS to Digital Converter USB 2.0 Video Converter Audio Capture Card"
Capture Compression: Uncompressed RGB/YCbCr
Capture Resolution: 720x480


Attached Images
File Type: jpg Timing.jpg (72.7 KB, 38 downloads)

Last edited by Masogir; 07-01-2019 at 03:40 PM.
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  #2  
07-01-2019, 03:43 PM
hodgey hodgey is online now
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Most likely the color space changed when you saved. Virtualdub filters often operate in RGB (i.e 24(8Red+8Green+8Blue) bits per pixel). You can see when adding a filter if there is a color space change next to the filter name Capture cards normally capture to some form of YUV 4:2:2, which means 8 bits brightness for each pixel, and 8 bits for each color channel for every other vertical pixel. This comes out as 16 bits per pixel combined, i.e RGB is 50% larger. So if you want to keep it in the same format after filtering, you would have to save it as YUY2 or YV16 or similar, rather than the default RGB.

I would really suggest using huffyuv or another lossless video codec instead though, there is pretty much no downside. Uncompressed is just a waste of space and it means longer loading times.
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  #3  
07-01-2019, 07:40 PM
sanlyn sanlyn is offline
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Quote:
Originally Posted by Masogir View Post
Should I even be capturing my old VHS tapes with this format to begin with?
No.

I don't know where you get your video information, but RGB and YCbCr are two different video storage matrices. You can't have both in the same video at the same time. So I'm not cure what you mean when you type "RGB/YCbCr". As alluded to earlier, RGB is a 4:4:4 matrix, YCbCrr is 4:2:2. RGB has more chroma resolution that YCbCr. VirtualDub and most video editors work in RGB.

VHS data is stored as YPbPr, not as RGB and not as YCbCr. The most commonly used colorspace for digital capture that resembles YPbPr is YUY2. VHS is usually captured as YUY2 using a lossless codec such as HuffYUV or something similar like Lagarith. As hodgey says, capturing uncompressed is a waste of space and CPU, and if you're capping to RGB it's an unnecessary conversion that many capture setups don't handle so well and results in illegal video signal levels. Also, although YCbCr and YUY2 are similar in some ways, they ain't exactly the same thing.

I don't know what a "VHS to Digital Converter USB 2.0 Video Converter Audio Capture Card" is, but I'm afraid to ask.

Last edited by sanlyn; 07-01-2019 at 07:51 PM.
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  #4  
07-02-2019, 04:47 AM
Masogir Masogir is offline
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Thank you both for responding. I'm very new to this VHS video capturing thing and learned a lot from your responses.

@hodgey
You were correct! I was capturing an uncompressed YUYV format and saving edits with the VirtualDub default RGB24 format. I'm going to take your advice and use a lossless codec (I chose Lagarith) with a YUV422 pixel format for archiving. As you suggested, doing so saves HDD space and waiting 1-2 minutes for frames to decode while editing in VirtualDub was absolute rage educing.

@sanlyn
"Uncompressed RGB/YCbCr" is a drop down selection for VirtualDub meaning uncompressed RGB or uncompressed YCbCr. Thank you for suggesting that RGB is unnecessary. This saved me time when choosing a color space and also lowered file sizes.

This is my capture card . The price is right for small projects. I'm not trying to capturing 20+ hours of priceless home videos like most of this community is trying to do .


Attached Images
File Type: jpg UCEC USB 2.0 Video Audio Capture Card Device Adapter.jpg (44.7 KB, 28 downloads)

Last edited by Masogir; 07-02-2019 at 04:59 AM.
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  #5  
07-02-2019, 05:00 AM
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lordsmurf lordsmurf is online now
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VirtualDub2 does some weird things on capture, regular 1.9.x is most suggested for now.

"Uncompressed RGB/YCbCr" refer to uncompressed with what is native to the device. It's either RGB, or YCbCr (YUV), but not both.

Uncompressed is large, and should almost never be used. The file size can cause dropped frames. Use lossless, preferably Huffyuv.

You probably captured YCrCb (4:2:2) and re-saved as RGB (4:4:4). Hence a larger 50%+ file size.

That capture card is s low-end POS. It's not "just cheap", but adds problems to the video. To be blunt, the conversion job will look so miserable that it should be reconsidered if it's even worth doing. And that's with a VCR with internal TBC, it's look completely dreadful from a consumer VHS deck. A sea of wiggles, over contrast, and blown out highlights, to name a few issues. I'm almost afraid to ask for sample clips.

UVYV is the alternate to YUY2, also native to some cards.

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  #6  
07-02-2019, 05:44 AM
Masogir Masogir is offline
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Quote:
Originally Posted by lordsmurf View Post
I'm almost afraid to ask for sample clips.

Wasn't able to find any rules for uploading samples. This is a 5 second capture using Lagarith:
Sample

I'm just going to assume you want a sample for personal interest. Whatever you have to say about this will not change my mind. I do not have the time nor money to invest in top notch equipment for such a small project.
Cheers!

EDIT: I forgot to mention that this was recorded on November 14, 1998.


Attached Files
File Type: avi Sample.avi (40.58 MB, 11 downloads)
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  #7  
07-02-2019, 05:53 AM
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Some of the EZcap and VHS VCR issues are obvious, but from the short clip it's not completely unwatchable as often happens. It's still below my standard, but I could watch it without getting noxious.

So that's something.

Old band videos make you really wish they had widescreen HD back in the day. The quality really sucked back then. Yours actually looks better than average. Modern kiddos don't realize how spoiled they are.

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  #8  
07-06-2019, 11:11 AM
Masogir Masogir is offline
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Juts wanted to upload a finished filtered/compressed sample. Source is an 8mm videocassette that was captured using a Sony CCD-TRV68 Hi8 with S-Video out and a mono -> stereo Y-Adapter. Same low-end POS capture card was used.

Seattle Aquarium Sample

I also wanted to thank admins/staff/etc for maintaining this forum. I've only publicly asked one question, but the knowledge gained behind the scenes from hours of reading old posts on this forum is priceless.


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File Type: mp4 Seattle_Aquarium(Jun1994).mp4 (32.14 MB, 5 downloads)
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