Quantcast Deinterlace during capture, or later? - digitalFAQ Forum
  #1  
08-07-2017, 07:03 PM
sanlyn sanlyn is offline
Premium Member
 
Join Date: Aug 2009
Location: N. Carolina and NY, USA
Posts: 2,290
Thanks: 76
Thanked 614 Times in 558 Posts
The following questions were submitted via PM. The forum moderators request that technical questions such as those in the email quoted below should be posted in the public forum where other readers can see the answers. That's the purpose of a forum. It also becomes a problem when the person receiving the PM might not know all the answers to a particular question, but other readers can contribute their expertise in a public post.

The questions show unfamiliarity with what interlacing is and how it is processed.

Quote:
if i capture raw with VDub,....
By "raw" I think you man capture to a lossless format. VHS and other analog source are usually captured as interlaced YUY2 color using lossless real-time compressors like huffyuv, Lagarith, etc. Capturing to uncompressed, RGB, or lossy media is not recommended and makes no improvement over lossless compression.

Quote:
if i capture raw with VDub, and the capture is interlaced, will programs deinterlace when you make dvds
DVD is either interlaced or partially interlaced using telecine. Most reputable DVD authoring programs will insist on interlace or telecine, and most will treat both true interlace and telecine as interlaced.

Almost all computer media players deinterlace or inverse-telecine during play. The exception is VLC player, which doesn't deinterlace by default (it can be set to do so in its "options" menu). Modern DVD and BluRay players are programmed to recognize DVD as an interlaced format and will deinterlace by default. For older players that don't deinterlace, the tv deinterlaces.

Quote:
im thinking i should figure out a way to deinterlace when capturing...

i really like the deinterlace features of amarectv, but i get errors on playback... using media player classic, and MPC plays everything no problems!
Are you saying that you "like" the shortcomings found in virtually all capture-time deinterlacers? If you're fond of defective playback, continue to deinterlace during capture. Capture cards and capture-time deinterlacers are two of the lest favored forms of deinterlace. They don't work properly with telecined video. Most will deinterlace by discarding alternate frames, throwing away 50% of the original temporal resolution, resulting in judder or choppy motion. The usual Inferior deinterlace methods also result in buzzing edges and/or aliasing, moire, stairstepping, line twitter, blurry field resizing, smeared motion, and (in the case of improper deinterlace involving telecine) a slew of artifacts including ghosting and periodic groups of duplicate frames. Those are some of the errors that occur with sloppy deinterlace, although we don't know which of those "errors" you refer to.

Are you saying that You get errors on playback using media player classic but not on "MPC"? I don't understand what that means. Media Player Classic and MPC are the same player.

Why are you deinterlacing? Double-rate deinterlace can't be used for DVD or standard definition BluRay, both of which are either interlaced or telecined. Deinterlacing always has a cost. Even the supposedly simple act of resizing two half-size fields into two motion-corrected full frames without interpolation artifacts and distortion is difficult Most capture cards and NLE's do an inferior job of it when compared to your media players, your tv, and to smart deinterlacers such as those in Avisynth. The premium deinterlacer these days is Avisynth's QTGMC, followed by NNEDI3, then by yadif. While yadif is better than some other methods, it can give alaising and other defects with animation and makes no attempt to smooth motion between interpolated fields. QTGMC is the cleanest method out there and is superior to many external players and tv's.

Deinterlacing always involves a quality cost, which is why deinterlacers like QTGMC are strongly favored for minimizing those losses. QTGMC can also be used to repair sloppy interlacing and many processing defects, and is often used as a general denoiser. A short video has been posted that contains 4 sections with the same video deinterlaced using various deinterlace methods. These methods include yadif, plus relatively simple bob used by many capture cards and some players, plus a method used by TempGaussMC, and the TDeint styled method used by other deinterlacers and some NLE's. The preferred and cleanest of the 4 sections is labeled "TempGaussMC", which is the coding and method source for QTGMC. The sample video comparison is here: stockholma_0-520_q3_yadif_mvbobmod_tgmca4_tdtmm.avi.


While deinterlacing always involves compromise, it's sometimes a necessary evil. It's required for web posting. For many filtering and repair operations, including resizing, purely progressive video is required. QTGMC makes many repairs and avoids many of the usual deinterlace defects. OTOH, telecined video must be inverse telecined with different filters, not deinterlaced. In both cases, for standard output formats like DVD or BluRay the video is either re-interlaced or new pulldown (telecine) flags are added when the video is re-encoded.

Quote:
if i could do huffy multithread in amarectv thatd be great, but like i said i get errors on playback when i capture with amarectv
What "errors"?

The older multithreading and the newer multi-core processing aren't the same thing. If you refer to huffyuvMT, it's obsolete and superceded by newer versions and by all other lossless compressors who passed up multi-threading a long time ago with newer technology.

Quote:
what is the raw codec Vdub uses?
I'm afraid you have to qualify that question. Which codec for which process? If you used AmarecTV's own lossy codec for capture, Virtualdub uses that installed codec to decompress your capture for display and processing as uncompressed RGB.

What's odd about this deinterlacing obsession is that you don't see people complaining about their interlaced retail DVD or BluRay discs, nor taking the time to deinterlace every TV show they see over their cable boxes. True, there's progressive streaming available today -- if you can stand the low-bitrate damage and other sloppy processing that afflicts these horrible broadcasts. But everyone has their own idea of quality.
Reply With Quote
Someday, 12:01 PM
admin's Avatar
Ads / Sponsors
 
Join Date: ∞
Posts: 42
Thanks: ∞
Thanked 42 Times in 42 Posts
  #2  
08-08-2017, 12:31 PM
x77x x77x is offline
Free Member
 
Join Date: Sep 2015
Location: escanabasucks@yahoo.com
Posts: 32
Thanks: 0
Thanked 0 Times in 0 Posts
what im getting at is

if its captured with the interlaced bars, isnt it going to stay like that?




raw signal from a vcr is one thing, a captured avi with bars is another...
Reply With Quote
  #3  
08-08-2017, 12:43 PM
sanlyn sanlyn is offline
Premium Member
 
Join Date: Aug 2009
Location: N. Carolina and NY, USA
Posts: 2,290
Thanks: 76
Thanked 614 Times in 558 Posts
What "bars" do you mean? Do you refer to interlace combing? Combing always appears in editors that don't deinterlace for display. They don't appear during proper playback. Do you see interlace combing on your HDTV broadcasts or when you play a DVD?

If you refer to the discoloration along the left border, it can be filtered out and cropped, along with the head-switching noise along the bottom border. It looks as if you also have some dot crawl, which can be cleaned. Did you use composite output for that capture?

Home video from consumer cameras often have excessive combing and aliasing effects, but they can be cleaned up.
Reply With Quote
  #4  
08-09-2017, 06:30 AM
x77x x77x is offline
Free Member
 
Join Date: Sep 2015
Location: escanabasucks@yahoo.com
Posts: 32
Thanks: 0
Thanked 0 Times in 0 Posts
normal



vdub deinterlaced filter



but if it captured with interlace combing, doesnt is stay like that once its put on to dvd or bluray?

raw s-video signal is obviously cleaned up by the tv or with whatever machine you watch it with, but a capture is a capture...
Reply With Quote
  #5  
08-09-2017, 09:51 AM
lordsmurf's Avatar
lordsmurf lordsmurf is online now
Site Staff | Video
 
Join Date: Dec 2002
Posts: 6,115
Thanks: 566
Thanked 886 Times in 796 Posts
Quote:
Originally Posted by sanlyn View Post
The forum moderators request that technical questions such as those in the email quoted below should be posted in the public forum where other readers can see the answers. That's the purpose of a forum. It also becomes a problem when the person receiving the PM might not know all the answers to a particular question, but other readers can contribute their expertise in a public post.
Correct.

Also, you can go ahead and just post their question in its entirety, as you first post. Just write something like "*** MODS, THIS IS A PM QUESTION ****" at the top. We can change ownership to the actual asker, or just the "via Email or PM" member.

Anyway....

Based solely on the title, this is an easy answer: never deinterlace at capture time.
It's just that easy.
Never.

"Bars" is jargon reserved for a type of noise. Don't use it here.
What I see in x77x's last capture is
(1) overscan noise, including head-switching noise on the bottom of the overscan area
(2) standard interlace combing aka NOT noise/error

If you want to deinterlace well, use QTGMC via Avisynth.
The best in VirtualDub is Yadif. It can often look well, though not always. Depends on image content.

- Did my advice help you? Then become a Premium Member and support this site.
- Find television shows, cartoons, DVDs and Blu-ray releases at the TVPast forums.
Reply With Quote
  #6  
08-09-2017, 10:18 AM
sanlyn sanlyn is offline
Premium Member
 
Join Date: Aug 2009
Location: N. Carolina and NY, USA
Posts: 2,290
Thanks: 76
Thanked 614 Times in 558 Posts
Quote:
Originally Posted by x77x View Post
but if it captured with interlace combing, doesnt is stay like that once its put on to dvd or bluray?
Interlaced video doesn't look that way when it's played in media players or on TV because players and tv's deinterlace during play. And they do it better than you can using most software.

Your capture card doesn't "capture combing" It captures interlaced frames. The combing shows up when you open that video in an editor.

Quote:
Originally Posted by x77x View Post
raw s-video signal is obviously cleaned up by the tv or with whatever machine you watch it with, but a capture is a capture...
I don't know what you mean by "raw s-video". A raw uncompressed signal can't be played on your tv.

Yes, the tv or media player cleans it up, and it will clean your interlaced encoded video the same way. That's the idea.

How does your capture look in PC media players that have built-in deinterlace? Do you see combing? When you play a DVD movie (a real DVD, not an internet download), do you see combing?

Interlaced frames contain two images arranged as fields. Each field contains a different image from different instants in time. The fields are arranged in alternating horizontal lines, with the first field starting at line 0 and the second field starting at line 1.
The deinterlaced image you posted contains only one of the images in the original frame. The second field contains an image of an action that occurred an instant later, but you didn't post that second instance.

Or test it this way: attached is a .png image of the same interlaced frame you posted above.



You can open that .png image in VirtualDub. When you first open it you'll see that the input panel and the output panel show the same combed image. Look at the frame counter at the bottom of VDub's window. It shows that you have a frame count of 1. Now mount the yadif deinterlace filter. In the filter setup dialog for "Deinterlacing mode", select "Interpolate using Yadif algorithm". In the "Field Order" column enable "Double frame rate, top field first". The filter setup dialog is shown below:



Close that setup dialog and you'll see that the frame counter at the bottom of the VDub window has changed from 1 to 2.

Now use the frame-by-frame scroll icons (<< and >>) to go back and forth between the output images. The frame-by-frame scroll icons are shown in the image below:



When you click the "<<" and ">>" back and forth, Use the frame-by-frame scroll icons (>> and <<) to go back and forth between the output images. The left-hand input pnel won't change. But the in the output panel you'll see that there is no combing and that there are two different images in that frame. Go back and forth with "<<" and ">>" and you'll see the two different actions in the two images in that frame.

Mount your capture in Virtualdub. Then load the yadif deinterlaing filter as shown above. Then scroll through your video one frame at a time looking at a sequence that contains motion. With the filter turned on, your input panel will show the same image that displays combing and won't change for two clicks of the scroll icon. The output image will change with each click, once for the top field, and then a second and different image for the bottom field. The same thing occurs when you play interlaced video properly.

I guess you really don't get it that VirtualDub isn't deinterlacing your video for display. Most NLE's don't deinterlace for display. Try it in Visual Studio, Vegas Pro, Premiere Pro, After Effects Pro, DaVinci Resolve, Final Cut Pro, or any other editor, cheap or expensive, and you'll see combing. So If all you want is PC playback (which is not the ideal way to watch movies) go ahead and deinterlace. VirtualDub is inferior to QTGMC, but since your video looks pretty soft anyway go ahead and use yadif in VDub. Your output frame rate will double and your file size will increase because the number of frames will double. If you drop frames when deinterlacing, you'll have choppy motion and judder and will throw away 50% of your resolution. You won't be able to make a DVD or BluRay from the results. Your choice.

And below, the "cleaned frame.jpg" attachment is the same interlaced frame with borders centered, bottom head switching noise removed, and most of the pink junk on the left border cleaned up in Avisynth and Virtualdub (can probably clean it more, but I'm short on time):


Attached Images
File Type: png original frame.png (516.3 KB, 14 downloads)
File Type: png yadif setup.png (11.9 KB, 14 downloads)
File Type: png frame by farme scroll.png (4.6 KB, 14 downloads)
File Type: jpg cleaned frame.jpg (78.2 KB, 14 downloads)

Last edited by sanlyn; 08-09-2017 at 11:08 AM.
Reply With Quote
  #7  
08-10-2017, 05:58 PM
lordsmurf's Avatar
lordsmurf lordsmurf is online now
Site Staff | Video
 
Join Date: Dec 2002
Posts: 6,115
Thanks: 566
Thanked 886 Times in 796 Posts
I tend to matte the frame more, and would simply hide all that pink mess.

NLEs use a simple drop-frame for display. Sadly, many NLEs also use it for output (yuck!), or some weenie "adaptive" method from about 15 years ago. Even Yadif is better, which was long ago superceded by YadifMod then QTGMC (and that was at least 5 years ago).

Yet HDTVs (usually) still do a better job of deinterlacing, using the built-in hardware deinterlacers.

- Did my advice help you? Then become a Premium Member and support this site.
- Find television shows, cartoons, DVDs and Blu-ray releases at the TVPast forums.
Reply With Quote
Reply




Similar Threads
Thread Thread Starter Forum Replies Last Post
Color Flicker after QTGMC Deinterlace mrb5217 Restore, Filter, Improve Quality 16 03-20-2017 04:15 PM
How to deinterlace, demux and encode DV to MPEG-2/MP4 bever Edit Video, Audio 1 02-07-2017 03:56 PM
How to deinterlace MP4 video + batch processing? segen77 Restore, Filter, Improve Quality 3 02-13-2014 11:43 AM
Will a TV always deinterlace video? premiumcapture Restore, Filter, Improve Quality 6 12-27-2013 11:06 AM
Deinterlace feedback from edDV admin Encode, Convert for discs 0 02-15-2005 05:09 AM

Thread Tools



 
All times are GMT -5. The time now is 08:17 PM  —  vBulletin Copyright Jelsoft Enterprises Ltd