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  #1  
06-12-2020, 07:13 AM
puleddu puleddu is offline
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When studying the material available on this website, I came across this paragraph from the article How to Capture MPEG Video with ATI All-In-Wonder Card (AIW)

Quote:
When capturing MPEG-2, encode interlaced! DO NOT DE-INTERLACE! You must leave the video interlaced. Your source is interlaced. Removing the interlace lines kills quality and causes stair-steps and/or blurring to appear in your video. When capturing MPEG-1, MMC will use deinterlace filters as mentioned earlier.
  • Does the first sentence mean: when capturing to MPEG-2 or from an MPEG-2 source?
  • Assuming it means to MPEG-2, and assuming I want to de-interlace, what would be the recommended procedure? To de-interlace at a later point with a different tool? Any recommendations?
  • Since, as stated in the same quoted paragraph, MMC uses deinterlace filters when capturing MPEG-1 (again, I'm assuming it means to MPEG-1), does it mean that quality will be compromised by default?

Thanks.

Last edited by puleddu; 06-12-2020 at 07:21 AM. Reason: Removed redundant link.
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  #2  
06-12-2020, 05:19 PM
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Quote:
Originally Posted by puleddu View Post
When studying the material available on this website, I came across this paragraph from the article How to Capture MPEG Video with ATI All-In-Wonder Card (AIW)


  • Does the first sentence mean: when capturing to MPEG-2 or from an MPEG-2 source?
  • Assuming it means to MPEG-2, and assuming I want to de-interlace, what would be the recommended procedure? To de-interlace at a later point with a different tool? Any recommendations?
  • Since, as stated in the same quoted paragraph, MMC uses deinterlace filters when capturing MPEG-1 (again, I'm assuming it means to MPEG-1), does it mean that quality will be compromised by default?

Thanks.
Does the first sentence mean: when capturing to MPEG-2 or from an MPEG-2 source?

- it depends if the MPEG2 source is interlaced or not interlaced, it can be either

Interlacing is whether a frame is transmitted as two pictures called "fields", or
(De-Interlaced) transmitted as one picture called a "frame"

Splitting a transmission into two (half) frames called "fields" was a bandwidth saving feature used by NTSC video so television could be transmitted over narrower RF channels. There is limited space in the RF spectrum electronics could "switch" or discriminate between without "blurring it all up" and not being able to distinguish anything from static or random noise.

Your (eye) performs the decode and "reassembles" the frame in your brain due to the persistence of vision and "interpolates" what happens in the interval of time between when the first field was captured and transmitted, and the second field was captured and transmitted. This is called "de-interlacing".

The fields are "laced together like -weaving- the lines or threads in a fine lace of cloth to produce a frame or square swatch of cloth"

There will be differences between the half frames.. motion is not smooth.. between the fields.

Your brain decodes the motion by "Estimating" what it sees to (make common sense) and fills in the logical gaps between the fields like it does between the frames of film projected in a theater. That is where they got the idea to use fields instead of frames from.. they just took it to another level when television was invented.

De-Interlacing is (never) recommended if your source (any source, composite, s-video, MPEG2) started out as interlaced.

There are (no) recommended "best" procedures for de-interlacing, because its never as good as an individuals "brain".. no computer program ever written is (so far) as good as your minds eye.

Every persons brain is different and "prefers" something else.

Today there are about 30 or 60 computer "methods" for de-interlacing, and it keeps getting larger all the time.. no one is going to suggest one method over another for fear of getting into an argument. Its like debating paintings.. everyone has an opinion, no one is actually correct.. information is missing from the beginning.. "filling in the gaps is never absolutely correct"

But.

De-interlacing (always) destroys information.

Once the fields are used up.. to make one frame.. they can never be "re-interlaced" without generation loss which appears as random "noise". This is the copy of a copy effect which eventually destroys all recognizable information in a copy of a copy.

If you never plan to copy the copy ever again.. the loss is fixed. But you choose to throw away information.. its gone.. it can never be retrieved.. there is no lossless reversal of a de-interlacing process.

That is why best practice is (do not de-interlace an interlaced capture).. that is the only true archival form.. everything else is a one-way compression which introduces errors into the result.

Today most computer generated video, or game capture video, or youtube video is made of (full frames) none of that is "interlaced". Television is now transmitted over the RF as compressed bit streams which are "full frames", none of that is interlaced. So "interlaced" content is falling out of favor.. people are forgetting what it is.. and want to dumb it all down so they don't have to remember or know the difference.

Older people want to forget what interlace video is, Younger people don't want to learn about a historical format that is becoming rare.. and to them is confusing.

So they choose to "de-interlace" without the big picture to think about.

They don't want to learn why "keeping it interlaced" is better than crunching the video with compression to "de-interlace".

The new younger people in the future will be even more disinclined to learn the difference.

So they pick a method and make the one-way leap.. and turn the interlaced video into poorer quality progressive.. and wonder why it looks worse than it looked before when it was still interlaced.

It makes their collections of video even more confusing.. because they didn't take the time to learn the advantages of just leaving it alone.. leaving it interlaced and not "mushifying it".

Some capture gear won't even capture in interlaced format and do it for you without telling you.

Apple Quicktime did this for DV back in the day.

Apple Quicktime "progressive-fied on playback" unless you turned on (High Resolution Playback) in the Movie Inspector hidden menus and suddenly DV looked as crystal clear as on Windows.

By removing choice. making choices for you Apple routinely makes video look worse on playback.. it looks great when you play it back on anything but a Mac.. but they make the video look worse on a Mac to make video editing and pushing icons around easier without making choices in the setups. When they give it to their friends who run Windows or Upload it to Youtube though.. it looks better because they made you suffer through poorer quality playback.

About one person out of 50 knows an Apple Mac will deliberately punish you for playing video.. without "subverting" the playback default settings.

Last edited by jwillis84; 06-12-2020 at 05:36 PM.
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06-12-2020, 05:35 PM
puleddu puleddu is offline
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Thank you, your answer completed with such a thorough background helped me to grasp the concept which I've often found a bit fuzzy.

You say the following:

Quote:
De-Interlacing is (never) recommended if your source (any source, composite, s-video, MPEG2) started out as interlaced.
Is this always true? I mean, I can appreciate that this is definitely true for the archive file. But what if you need to playback the capture in a medium that is not supposed to reproduce interlaced material?

I mean, an even wider question is: if it's never recommended then why de-interlacing tools even exist? What's the purpose of having such a tool? There must be a use case for de-interlaced videos, no?
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06-12-2020, 05:58 PM
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De-interlacing was always done for iPods and early low end low power video playback devices.

But chips got more powerful and hardware decoding moved that to chips other than the CPU of the low end device.. speeding things up.. so they could de-interlace on the fly.

A CRT is perfect for displaying interlaced content.. it was designed for that.

A Plasma TV was perfect for displaying interlaced content.. it was designed for that.

An LED or LCD display was designed for Progressive "full frame" content.. initially for Computers, later for Televisions.

LED or LCD Televisions came out before interlaced video stopped being played back from DVD players and over the air from NTSC broadcasts.. so those had dedicated de-interlacing chips.

After the transition to Digital broadcasts, some content arrived interlaced (720i, 1080i) or progressive (720p, 1080p) so the TV had to support both.

Some TVs today don't have Inputs.. so you can't even input an interlaced signal into them anymore.. so eventually those will only support Progressive (progressive means "de-interlaced") content.

On Computers.. we have far more powerful CPUs and lots of software, public domain and commercial for supporting both interlaced and progressive playback. So it will never be a problem.. our software will always autodetect the format, and select the proper decoder software in the background and play it back on your CRT or LCD monitor for you.

Again.. Interlaced will look better on a CRT, but if played back it will look okay on an LCD.. but future advantage is the de-interlace on the fly software can keep getting better over the years.

MPEG2 was carefully selected back in the 1990's for supporting film to interlaced television playback.. they widened the screen, increased the audio formats supported and made sure it was as close to a Theater experience as possible for the home market.. it holds up pretty well today. But it is usually used with and for interlaced content.. it can be used in many ways.. but by and large people use it in the interlaced form.. so its become synonymous with NTSC interlaced video with very high quality video signal input.

Personally I think one of the strange but great things is that MPEG2 "can support interlaced" video.. and preserve that as lossless.. where its lost when using many of the newer higher compression formats... as a matter of default.

Will there ever be a reason you (must) de-interlace your video?

Maybe.. but not logically.. de-interlacing is destructive.. unless someone finds a way of time traveling and re-capturing the actual scenes presented for interlacing.. filling in the gaps with "spackling paste" will always be a reality.

All the Computers in the world could be destroyed and all the public domain software in the world capable of de-interlacing on the fly could suddenly be wiped out.. or we could have to go back to wearing leathers and using stone utensils.. then you might have to de-interlace and print all the frames of your video.. but its an "edge" case.. I wouldn't worry about.

The use case I believe most commonly "used" would be when "blending" different video content types in a single video editor timeline.

You don't want to upload a video to youtube or burn it to dvd or bluray or give it to someone when the video format keeps shifting from one type to the other.. that will crash some video players.

So when "printing" a copy for distribution.. the final step in most video editors is to (render) all the variable formats into one single video format for output or upload. Today the common denominator is usually a progressive format.. and that means any interlaced video has to be de-interlaced during rendering to the common progressive format.

Last edited by jwillis84; 06-12-2020 at 06:22 PM.
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  #5  
06-12-2020, 06:16 PM
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My project is a small but challenging one, considering I'm trying to hold myself to relatively high standards and I'm no more than a newbie: I'm aiming to digitalize my dad's VHS and negative/slide film archive. For both things I tried to build the best system that my budget allowed. The video material is made of home tapes only (i.e. kids, vacations, etc.)

Once I'm done acquiring these and have them available in digital format, and decent quality, I'd like to upload them to a web service like SmugSmug or Google Drive and have that shared with my family. I'd still be keeping the lossless version of whatever I captured, for archival purposes, but that's irrelevant to my question.

So, I'm not after perfect archival quality, but I do really want to avoid a sloppy job, and that's why I'm trying to learn as much as possible – I find it fun as well.

Would the upload to any of these web services (e.g. SmugSmug, Google Drive, Vimeo, Youtube) require de-interlacing? Or do they support de-interlacing on the fly with their player as well?
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06-12-2020, 07:52 PM
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All upload archives have their own form of import.

Usually its totally out of your control, it works or does not work.. and then you start troubleshooting.

Generally even they are newbies at it and don't care about quality, they are a warehousing or storage business, ingesting video is a drain on their funds or profit.. so they give very little support.

Communities grow up around the ingest point online forums and boards which commiserate and share tips and best practices.. its mostly "bros science" and trial and error.

As a customer what your seeking in a service to distribute your product and simplify playback for other people not technically experienced.. that varies quite a bit from person to person.. and by age group.

It (sounds) attractive to upload and forget

It (feels) responsible to do the best job you can on the inbound side and then let someone else handle the download and playback

your likely to be disaappointed..

DVD's were about as good as you could get at sharing video that everyone could sort of understand

Physical mailing a USB thumb drive is the most common method today

Online.. beyond uploading it to YouTube for free.. most people wouldn't bother.. its the common watering hole for anyone trying to watch a video.. you upload.. wait for Google servers to de-interlace and reformat your video.. then grab the sharable URL and email that to people who care

If you want to build collections on YouTube, then you create "Playlists" and share those links.. and people try to watch on their phones or browser

Some people try to use Facebook.. but that gets mined for data and invades a lot of peoples privacy by tagging GPS location and peoples faces to webify them all together and start assigning shopping habits to them so they can spam them with ads.. Facebook is pretty craven these days.. but its pretty popular with Grandparents and older Parents

Google does same as Facebook.. just a little more stealthily.. somebody has to get paid for storing your video

Other places than those generally charge you a monthly storage fee for your videos.. and some leave even more up to you about the video content.. like its format.

Anything online is not archival.. and will be wiped by housekeeping or "changes in business policy" about every three years.. it just happens.. nothing you can do about it.. all that work you put into it.. will be gone. And there will likely be a new platform or preferred method for people to watch videos.. if they still care.. Ancestry dot com seems to be getting into the video business too.. but their longevity at holding on to things is not proven

So never under estimate your personal archives.. or under estimate the need for sorting and storing copies off site.

If you really want to hang on to video, or 8mm film or slides.. you have to bring them into a PC digital format.. and keep moving them.. from one format and hard drive size to another.. reviewing or checking up on them to make sure they aren't degrading.. and realize.. eventually nobody will care.

Life moves on.. and we eventually drop things by the way side or whittle down the collection of media to things more currently important to us. Your videos of your grandparents will be important to you.. but mean less and less as kids and their kids are born.. that's just how it is.

The Ultimate backup is the source material itself.. but over the years it becomes Big and Bulky, Corrodes and Errodes and the playback devices stop being made.. and those are why you have to convert it into something else.. and keep moving it. Hard drives and size keep changing, computer file systems, commonly used software.. keeps changing.. ot keep access you have to keep updating and trans coding the format from one form to another.

You may "think" you will go back to the original reference material.. but what if there is a fire? what if that projector no longer works? what if they stop making D-VHS players? or DVD players? or 5.25 inch floppy drives?

You've heard it all before.. (this time is different) (oh they would never do that) (2.5 inch floppies for a Mac are forever!) .. lazy procrastination.. every format comes to an end.. and very quickly too.. well within a human lifetime.

The snake oil today is oddball format of tomorrow.. 3000 year Millennium discs are made in DVD, Bluray.. and now tape format.. think those will be readable in 3 years.. let alone 300 ? Who will make the drives? - Who made them 300 years ago?

Last edited by jwillis84; 06-12-2020 at 08:13 PM.
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  #7  
06-12-2020, 09:08 PM
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Some thoughts:
Quote:
Does the first sentence mean: when capturing to MPEG-2 or from an MPEG-2 source?
It must mean "to" MPEG-2, because MPEG 2 itself is a digital format. MPEG 2 only exists on DVDs and the like, which you would never "recapture"; you'd just rip the digital files off and work with them.

Quote:
Assuming it means to MPEG-2, and assuming I want to de-interlace, what would be the recommended procedure? To de-interlace at a later point with a different tool? Any recommendations?
The overwhelming recommendation at DigitalFAQ, as far as I have read, is don't de-interlace. All TVs can deinterlace automatically. But I find that with VLC Player (maybe not the best player out there?) I have to set the de-interlacing to "On" (not auto) to get it to display a interlaced video nicely.

The only issue appears to be what do you deliver to the online services, as their output is progressive/de-interlaced. Do you upload de-interlaced video or do you let them de-interlace it? For me, this is a moot point because I upload in MP4, which I believe cannot be , by definition, "interlaced".

Re capturing, my understanding is MPEG-2 is a lossy format. If you capture in MPEG-2, you're compressing. You'll then edit it and then compress it/render it again (unless your editor can smart-render) for the final output. If you capture lossless (I use Lagarith with Virtual Dub) then you're saving one generation of quality, at the expense, of course, of large file sizes (MPEG 2 ~max 100mb/min, Lagarith 500mb/min).

I understand that applying all those VHS-type filters eg noise reduction, colour correction is much better done on the lossless files rather than already-compressed/processed MPEG-2.

All that said, looking at my MP4s verses the interlaced VDub originals: I can't tell the difference! Lordsmurf will probably tell me to get my glasses cleaned. Was that with Isopropyl at 99% or only 97?

Last edited by Hushpower; 06-12-2020 at 09:33 PM. Reason: VLC Player note, final para.
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  #8  
06-12-2020, 09:53 PM
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Quote:
Originally Posted by Hushpower View Post
Some thoughts:
It must mean "to" MPEG-2, because MPEG 2 itself is a digital format. MPEG 2 only exists on DVDs and the like, which you would never "recapture"; you'd just rip the digital files off and work with them.
Well, mostly. In years past, you'd record satellite/cable to DVD. The broadcast was MPEG2, and the DVD was MPEG2. It was D>A>D, so there was an analog step in there, no way to rip the satellite/cable source files (at least legally, and without special equipment).

Quote:
don't de-interlace. All TVs can deinterlace automatically.
Correct.

But I find that with VLC Player (maybe not the best player out there?) I have to set the de-interlacing to "On" (not auto) to get it to display a interlaced video nicely.

Quote:
MP4, which I believe cannot be , by definition, "interlaced".
It can be. But viewer devices usually don't expect it.

Quote:
MPEG-2 is a lossy format.
Correct ... sort of.
- Technically, always lossy.
- Visually, with 4:2:2 and high bitrates, not so much.

Quote:
If you capture in MPEG-2, you're compressing. You'll then edit it and then compress it/render it again (unless your editor can smart-render) for the final output.
Correct, don't edit MPEG.

Quote:
I understand that applying all those VHS-type filters eg noise reduction, colour correction is much better done on the lossless files rather than already-compressed/processed MPEG-2.
Not just better, but "possible". Lossy compression can obliterate the data to an unrestorable mess.

Quote:
All that said, looking at my MP4s verses the interlaced VDub originals: I can't tell the difference! Lordsmurf will probably tell me to get my glasses cleaned. Was that with Isopropyl at 99% or only 97?
If done correctly, the MP4 could be even be better than the original.

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06-13-2020, 04:25 AM
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Thank you all for your contribution, all this really helped me to clarify my plan, which is:
  1. get the best lossless digitalization I'm able to produce from the source
  2. dry store the source
  3. se the lossless material to produce the best lossy (interlaced/de-interlaced) format for the destination use
Knowing more about the nuances of MPEG-2 and the interlace/de-interlace topic, I feel more comfortable moving forward.

I'll be researching in more detail how the service I'll end up using is treating my uploads and feed them what's more appropriate – I imagine I might have more detailed questions once I figure things out.

Either way, my plan is to keep a lossless version of everything. Those files will be securely and redundantly stored independently from the service or the interlaced/de-interlaced version I might need to produce from them.
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06-13-2020, 11:05 AM
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Quote:
Originally Posted by jwillis84 View Post
Some TVs today don't have Inputs.. so you can't even input an interlaced signal into them anymore.. so eventually those will only support Progressive (progressive means "de-interlaced") content.
Do you mean "some TVs today don't have ANALOG inputs."? Lack of analog inputs doesn't mean, that you can't input interlaced video via HDMI!
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