"interlace"

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"interlace"

Mark Filipak
Admittedly, this is an anal-compulsive topic. But good documentation often requires anal compulsion.
Good documentation definitely requires thorough knowledge of language usage.

The topic is use of the various forms of the word "interlace". But I'm going to use the word "build"
as an example because it has more, and more varied cases.

"Let's build it" -- "build" as a verb.
"We will be building it" employs "build" as a present participle.
"Assemble the building crew" is the present participle used as an adjective (the crew is actively
engaged in building something, so it is the "building crew" as opposed to some other "crew").
"It's a tall building" employs "build" as a verbal noun.
"Assemble the building's crew" is the verbal noun used as a possessive adjective (the crew is
associated with "the building" as opposed to some other crew that's not associated with "the
building") in the same way that "the cat's meow" uses the ordinary noun, "cat", as a possessive
adjective.

In the case of "interlace":
"It's interlaced video" -- video in which the lines alternate (i.e. are interlaced) between two (or
theoretically, more) fields (e.g. odd-even-odd-even...). That employs the past participle of the
verb, "interlace", as an adjective to modify "video".

H.262 refers to "interlace video" when referring to hard telecine. But "interlace video" is a bit of
a mutt. "Interlace" is clearly being used as an adjective, yet "interlace" is not a participle (past
or present) -- "interlaced" is the past participle and "interlacing" is the present participle. What
it would have to be is a verbal adjective (i.e. a verb used as an adjective). I may be wrong, but I
don't think there exists such a thing as a verbal adjective.

A hard telecined video residing on a disc is clearly not interlaced. It is clearly deinterlaced
(i.e. stored in fields). Since it is deinterlaced, it can be fed directly to a scanning TV (i.e.
CRT) provided it is of the proper frame rate, or it can be interlaced -- a verb -- by a decoder as
part of the decoding step.

Conclusion: Employing the past participle, "interlaced", to a field-based video stream is just plain
wrong. All of the ffmpeg documentation that uses the word "interlaced" should be checked for accuracy.
--
Racism is like roaches. When you switch on the light, they scurry.
But if you don't switch on the light, you don't know they're there.
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Re: "interlace"

Bouke-3

> On 06 Sep 2020, at 21:26, Mark Filipak <[hidden email]> wrote:
>
>
> Conclusion: Employing the past participle, "interlaced", to a field-based video stream is just plain wrong.

Can you just shut up / stop spreading nonsense?

Bouke

Edit ‘B / VideoToolShed.com
van Oldenbarneveltstraat 33
6512 AS  Nijmegen
+31 6 21817248


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Re: "interlace"

Carl Eugen Hoyos-2
In reply to this post by Mark Filipak
Am So., 6. Sept. 2020 um 21:27 Uhr schrieb Mark Filipak
<[hidden email]>:

> All of the ffmpeg documentation that uses the word "interlaced"
> should be checked for accuracy.

Since real-world users are using this documentation it should only
be carefully changed.

Or in other words: We will certainly not change our definition of
"interlaced video" - many people seem to understand it.

Carl Eugen
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Re: "interlace"

Mark Filipak
In reply to this post by Bouke-3
On 09/06/2020 03:32 PM, Bouke wrote:
>
>> On 06 Sep 2020, at 21:26, Mark Filipak <[hidden email]> wrote:
>>
>>
>> Conclusion: Employing the past participle, "interlaced", to a field-based video stream is just plain wrong.
>
> Can you just shut up / stop spreading nonsense?

How is it nonsense? The present participle, "interlaced", is being misapplied by people who exhibit
poor language usage and it's unfortunately caught on. ffmpeg is unintentionally helping to spread
the misapplication.

This controversy and prejudice in favor of poor usage is why I recommend that "interlace" be retired
in favor of "interleave".
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Re: "interlace"

kumowoon1025
In reply to this post by Mark Filipak
Hi,

> In the case of "interlace":
> "It's interlaced video" -- video in which the lines alternate (i.e. are interlaced) between two (or theoretically, more) fields (e.g. odd-even-odd-even...). That employs the past participle of the verb, "interlace", as an adjective to modify "video".
>
> H.262 refers to "interlace video" when referring to hard telecine. But "interlace video" is a bit of a mutt. "Interlace" is clearly being used as an adjective, yet "interlace" is not a participle (past or present) -- "interlaced" is the past participle and "interlacing" is the present participle. What it would have to be is a verbal adjective (i.e. a verb used as an adjective). I may be wrong, but I don't think there exists such a thing as a verbal adjective.
That's more or less what a participle is.

> A hard telecined video residing on a disc is clearly not interlaced. It is clearly deinterlaced (i.e. stored in fields). Since it is deinterlaced, it can be fed directly to a scanning TV (i.e. CRT) provided it is of the proper frame rate, or it can be interlaced -- a verb -- by a decoder as part of the decoding step.

Is it? Hard telecine is like telecining film and then recording it on a VCR, isn't it? And you don't need to deinterlace interlaced video to display it on an interlaced scanning TV. I think the confusion is when you deinterlace interlaced video, it is still interlaced video (or at least I think of it that way).

Regards,
Ted Park

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Re: "interlace"

Mark Filipak
On 09/06/2020 04:16 PM, Edward Park wrote:

> Hi,
>
>> In the case of "interlace":
>> "It's interlaced video" -- video in which the lines alternate (i.e. are interlaced) between two (or theoretically, more) fields (e.g. odd-even-odd-even...). That employs the past participle of the verb, "interlace", as an adjective to modify "video".
>>
>> H.262 refers to "interlace video" when referring to hard telecine. But "interlace video" is a bit of a mutt. "Interlace" is clearly being used as an adjective, yet "interlace" is not a participle (past or present) -- "interlaced" is the past participle and "interlacing" is the present participle. What it would have to be is a verbal adjective (i.e. a verb used as an adjective). I may be wrong, but I don't think there exists such a thing as a verbal adjective.
> That's more or less what a participle is.
>
>> A hard telecined video residing on a disc is clearly not interlaced. It is clearly deinterlaced (i.e. stored in fields). Since it is deinterlaced, it can be fed directly to a scanning TV (i.e. CRT) provided it is of the proper frame rate, or it can be interlaced -- a verb -- by a decoder as part of the decoding step.
>
> Is it? Hard telecine is like telecining film and then recording it on a VCR, isn't it? And you don't need to deinterlace interlaced video to display it on an interlaced scanning TV. I think the confusion is when you deinterlace interlaced video, it is still interlaced video (or at least I think of it that way).
>
> Regards,
> Ted Park

I have great respect for you, Ted. Tell me: What is interlaced video?
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Re: "interlace"

Mark Filipak
In reply to this post by Carl Eugen Hoyos-2
On 09/06/2020 03:33 PM, Carl Eugen Hoyos wrote:

> Am So., 6. Sept. 2020 um 21:27 Uhr schrieb Mark Filipak
> <[hidden email]>:
>
>> All of the ffmpeg documentation that uses the word "interlaced"
>> should be checked for accuracy.
>
> Since real-world users are using this documentation it should only
> be carefully changed.
>
> Or in other words: We will certainly not change our definition of
> "interlaced video" - many people seem to understand it.

Do they really? There are alternatives that are more appropriate.
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Re: "interlace"

Mark Filipak
In reply to this post by kumowoon1025
On 09/06/2020 04:16 PM, Edward Park wrote:

> Hi,
>
>> In the case of "interlace":
>> "It's interlaced video" -- video in which the lines alternate (i.e. are interlaced) between two (or theoretically, more) fields (e.g. odd-even-odd-even...). That employs the past participle of the verb, "interlace", as an adjective to modify "video".
>>
>> H.262 refers to "interlace video" when referring to hard telecine. But "interlace video" is a bit of a mutt. "Interlace" is clearly being used as an adjective, yet "interlace" is not a participle (past or present) -- "interlaced" is the past participle and "interlacing" is the present participle. What it would have to be is a verbal adjective (i.e. a verb used as an adjective). I may be wrong, but I don't think there exists such a thing as a verbal adjective.
> That's more or less what a participle is.
>
>> A hard telecined video residing on a disc is clearly not interlaced. It is clearly deinterlaced (i.e. stored in fields). Since it is deinterlaced, it can be fed directly to a scanning TV (i.e. CRT) provided it is of the proper frame rate, or it can be interlaced -- a verb -- by a decoder as part of the decoding step.
>
> Is it? Hard telecine is like telecining film and then recording it on a VCR, isn't it? And you don't need to deinterlace interlaced video to display it on an interlaced scanning TV. I think the confusion is when you deinterlace interlaced video, it is still interlaced video (or at least I think of it that way).
>
> Regards,
> Ted Park

"interlace [transitive verb]: 1. To connect by or as if by lacing together; interweave. 2. To
intersperse; intermix: 'interlaced lies with truth'. [intransitive verb]: To intertwine."

The word "interlaced" is universally applied to scan fields. Scan fields are not interlaced. The
lines are aggregated into odd and even fields (i.e. blocks at the macroblock level) but the rows
("lines" if you will) are not interlaced. Scan fields are interleaved, but that is not interlacing.
If anything, that is deinterlacing.

Given the historic misuse of "interlace", I will continue to use alternatives. The best alternative
is "field-based". Next is "unweaved". Also acceptable is "interleaved" because that aptly describes
the condition of the fields.
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Re: "interlace"

kumowoon1025
In reply to this post by Mark Filipak

> I have great respect for you, Ted. Tell me: What is interlaced video?

Well that is unwarranted, possibly spiteful, even, to someone as insecure as me ;)

That is the real question isn't it. Probably won't be very satisfying but I'll try to describe it. Probably not useful to say it's video that is interlaced (or to be interlaced) lines. Video as in not film? When individual frames don't correspond to a single moment in time.

Regards,
Ted Park

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Re: "interlace"

Mark Filipak
On 09/06/2020 05:24 PM, Edward Park wrote:
>
>> I have great respect for you, Ted. Tell me: What is interlaced video?
>
> Well that is unwarranted, possibly spiteful, even, to someone as insecure as me ;)

Hahahaha... Ted I want you to do something for me. Take your right hand, put it over your left
shoulder, extend it down your back, and, with an open palm, slap it against your back two or three
times. This list is a better place with you in it.

> That is the real question isn't it. Probably won't be very satisfying but I'll try to describe it. Probably not useful to say it's video that is interlaced (or to be interlaced) lines.

Well, that's interesting. Is interlaced *lines* a requirement for interlaced video? I would say so,
but tell me: How does what is called interlaced video related to interlaced *lines*?

> Video as in not film? When individual frames don't correspond to a single moment in time.

Well, there you go. That's what everyone says. But a video that is field-based (aka "interlaced",
yuck!) can also portray a single moment in time. In fact, the vast majority of so-called
"interlaced" video is actually concurrent. I'm sure you agree with that, eh? So, if "interlaced" is
not really a good word for "in fields" or "composed of fields", then what is a good term?

Variables:
Frame-based v. field-based
Concurrent v. successive (or, if you prefer, pictures v. scans)

There are 4 combinations:
1, Frame-based pictures
2, Field-based pictures
3, Frame-based scans
4, Field-based scans

Number 1 seems reasonable. Agreed?
If a picture is an image that completely fills the frame, then number 2 is a contradiction in terms.
Agreed? I use the term "half-picture" for the fields extracted from a frame. What do you think of that?
Number 3 is possible, but not desirable due to excessive combing. Agreed?
Number 4 applies to streams that were generated by scanning cameras (TV studios) to be viewed on
scanning TVs (CRTs), so is not really applicable for new video, today. Nonetheless, they do exist,
if only as legacy video. Agreed?

1, Frame-based pictures
2, Field-based half-pictures
3, Frame-based scans -- beware!
4, Field-based scans -- legacy

What do you think?

> Regards,
> Ted Park

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Re: "interlace"

Carl Zwanzig
In reply to this post by Carl Eugen Hoyos-2
On 9/6/2020 12:33 PM, Carl Eugen Hoyos wrote:
> Or in other words: We will certainly not change our definition of
> "interlaced video" - many people seem to understand it.

Sounds rather strong ("certainly not"), but those of us coming from the NTSC
analog world all understood the concept of "interlaceD video" and the
various word forms of it. We also understood the 5-blade shutter, 3:2
pulldown, etc. Unfortunately, that often gets muddied when people coming
from the progressive-scan world try to understand it.

Ref- https://en.wikipedia.org/wiki/Interlaced_video (which is pretty good)

With all of the latent issues with the ffmpeg docs, arguing over a "d" does
not seem productive.

Later,

z!
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