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View Full Version : Weird "Broken Line" artifact when viewing DVD rips




godslabrat
Apr 19, 2010, 12:06 PM
Hi all.

I've been ripping for a while now, but it seems that some DVDs just look better than others after ripping. One artifact I notice most often is a "broken line" effect, where it almost seems as if two different frames are being displayed at once, and the lines of resolution are split between them. This is most noticed in scenes with lots of movement. Here's a particularly bad example:

http://i207.photobucket.com/albums/bb258/linkvb06/55f150f6.jpg

The effect only lasts for half a second, but it can be distracting.

Here's what I'm using:

Intel Mac Mini
3GB RAM
OSX 10.4
Handbrake w/PS3 Presets, 2500 Mbps, have tried both single and double pass rips
PS3 for playback

All help is appreciated.



wysinawyg
Apr 19, 2010, 12:14 PM
Its an intelaced image (a TV show presumably?).

Assuming you're using the GUI you want to go into picture settings and either:

1. if you want to be able to use it all the time without worrying about whether the image needs it tick "Decomb" in the Filters tab; or

2. if you want to properly fix it with a bit better quality but on the basis that you will screw up non-interlaced progs if you forget to untick it tick "Deinterlace" and choose from fast, slow etc. with the slower versions being better quality but slower encode times.

wysi

dynaflash
Apr 19, 2010, 12:15 PM
Um, thats because your video is interlaced. Turn on deinterlacing or decomb.

http://trac.handbrake.fr/wiki/HandBrakeGuide

godslabrat
Apr 19, 2010, 12:24 PM
Wow, thanks for the help. I really appreciate this.


Its an intelaced image (a TV show presumably?).

Assuming you're using the GUI you want to go into picture settings and either:

1. if you want to be able to use it all the time without worrying about whether the image needs it tick "Decomb" in the Filters tab; or

2. if you want to properly fix it with a bit better quality but on the basis that you will screw up non-interlaced progs if you forget to untick it tick "Deinterlace" and choose from fast, slow etc. with the slower versions being better quality but slower encode times.


The above image is from the movie "The Life and Death of Peter Sellers". Oddly enough, my episodes of Stargate SG1 almost never show significant artifacts.


Um, thats because your video is interlaced. Turn on deinterlacing or decomb.

http://trac.handbrake.fr/wiki/HandBrakeGuide

Generally, I don't worry too much about how long it takes to encode, I just set it to run before I go to bed. So, if I can make this better by adding an extra two hours to encode time, I'm all for that.

roidy
Apr 19, 2010, 02:16 PM
Just turn 'Decomb' on and leave it on all the time. The problem with deinterlace is that it will deinterlace every single video frame and some if not most DVD's contain a mixture of both progressive and interlaced frames and deinterlacing a progressive frame will reduce it's quality making it look bad.

Where as the Decomb filter will look at each frame of the video and detect if it's interlaced and only deinterlace it if needed. I leave Decomb turned on for everything I encode and I've never had any problems with interlacing artifacts like your picture.

fpnc
Apr 19, 2010, 04:15 PM
...some if not most DVD's contain a mixture of both progressive and interlaced frames and deinterlacing a progressive frame will reduce it's quality making it look bad...
What you're talking about here is the result of the "hard" telecine operation that takes place when film at 24fps is converted to 30fps for broadcast at NTSC frame rates (30 frames per second, which is 60 interlaced fields per second). In its standard form, telecine takes four fames of progressive material and outputs five frames with three essentially unaltered frames (progressive in nature) followed by two frames that combine fields from what were previously progressive frames (think of this as a 3:2 cadence, sometimes called 3:2 pulldown).

Here is a link that explains this process:

http://www.projectorpeople.com/resources/pulldown.asp

Unfortunately, editing operations can cause breaks in this 3:2 cadence which not only makes the inverse telecine operation difficult but it may also result in real data loss from the original progressive source. If, however, the cadence is left unbroken throughout the entire video sequence then a reverse telecine operation can return the content back to a fully progressive state. Sadly, I've never seen a case where a delivery mechanism (DVD or broadcast TV) included telecined content that had unbroken cadence (which means that even after a reverse telecine you're going to see random field/interlacing errors in the converted material). Thus, the only effective technique on such material may be to use a "smart" deinterlacer such as Handbrake's decomb filter (thus leaving the video in a 30fps state).

It should be noted, however, that not all DVDs undergo "hard" telecine. Many film-based DVDs contain fully progressive content and thus don't need to be deinterlaced, decombed, or inverse telecined.

roidy
Apr 19, 2010, 05:07 PM
Thus, the only effective technique on such material may be to use a "smart" deinterlacer such as Handbrake's decomb filter (thus leaving the video in a 30fps state).

Which is what I said in my post...... Use Decomb.

It should be noted, however, that not all DVDs undergo "hard" telecine. Many film-based DVDs contain fully progressive content and thus don't need to be deinterlaced, decombed, or inverse telecined.

And many DVD's still contain interlaced portions, which is why leaving Decomb on is the best option. You then get the best of both worlds, any progressive content is left untouched and any interlaced content is deinterlaced.

fpnc
Apr 19, 2010, 06:24 PM
...And many DVD's still contain interlaced portions, which is why leaving Decomb on is the best option. You then get the best of both worlds, any progressive content is left untouched and any interlaced content is deinterlaced.
However, we shouldn't be confusing the results of the frame-by-frame interlacing that occurs in all NTSC 60-field-per-second video content and the effects from the telecining of film-based materials. Although the end results may look somewhat the same to the untrained observer the handling of such content may want to be different.

I've found cases where Handbrake's Decomb filter will actually introduce defects that can be avoided with a properly applied deinterlace filter. Furthermore, there will be some cases where an inverse telecine will produce results that are significantly better than Decomb, although as I stated in my earlier post cadence breaks often make a simple inverse telecine operation somewhat lacking (in those cases, inverse telecine to 24fps followed by a decomb can produce good results).

Nevertheless, for a lot of content, or when you aren't being absolutely critical about the quality of the result, Handbrake's Decomb filter works pretty well.