Talk:GIF

PIG

This article should include the additions currently, i.e. after the rejection of APNG, under discussion to embed PNG in GIF, called PNG-in-GIF (PIG) and RGBA-in-GIF, whether they are accepted in the end or not.

Actual format?

There's no actual information in the article about how the format actually works. I mean it says it's 8bit and that there can be frames but I would like to know what a GIF file actually has in it byte by byte. The link oto the spec has the info but that's more detail than I need. Wikivek (talk) 19:03, 29 March 2008 (UTC)

" ... what a GIF file actually has in it byte by byte." Sounds like the spec to me. If we were to rehash the spec here, how can we be expected to predict how much detail you need? There's a link to the spec, and that's absolutely the right solution. Elphion (talk) 16:56, 11 November 2009 (UTC)

Programming question moved to User talk:Vmelkon -- Elphion (talk) 18:30, 10 February 2018 (UTC)

the meaning of "GIF" has broadened

i don't know where to add this (the disambig? lone sentence in the lead?) but in contemporary usage (2018) the term "gif" now refers to a short, looping video or animation, no matter what format this in. Twitter prominently displays a [GIF] box over these small looping videos, even though there are mostly mp4. to be clear, i don't care about the technical side (so perhaps this page, actually about the technical file, is wrong?) but the linguistic side. We use "GIF" nowadays to mean something that is NOT "Graphics Interchange Format", even though the usage derives from here. 2A02:8109:9A80:6F6C:3006:3246:A00A:BBD2 (talk) 23:08, 23 July 2018 (UTC)

Wikipedia is not a dictionary, and definitely not Urban Dictionary. —DIYeditor (talk) 01:47, 24 July 2018 (UTC)

Proposed merge with Video alternative to GIF

Video alternative to GIF does not currently merit a whole separate article. Ethanpet113 (talk) 01:49, 13 January 2019 (UTC)

Support/Merge I was actually searched GIF, but I was really looking for the stub article Video alternative to GIF. ―Matthew J. Long -Talk-^☖ 04:54, 17 January 2019 (UTC)

Support I'm kinda split on this one. I agree that a stub doesn't really work for Video alternative to GIF, but not really sure how it would be included in the article. I originally was going to stay neutral, however, the more I think about it when writing this reply, the more I support this merger. GeekInParadise (talk) 17:53, 26 March 2019 (UTC)

User Since video is an alternative to all image-based animation formats like APNG, animated WebP and others, I actually think that it would be better to rename the article to Video alternative to animated images and link to it from GIF, APNG and wherever else needed. --Fernando Trebien (talk) 20:22, 24 June 2019 (UTC)

User For the reason that the article on Video alternative to GIF, in its current state, is short, I would suggest either merging the two articles and having the Video alternative to GIF page redirect to GIF; adding a very brief introduction on video alternatives to Graphics Interchange Format (under which, "see full article here" would link to the full page); or mentioning alternatives to the format in the See Also section. Among those three options, I would personally go with the introduction with the "see full article here" under the heading. ~Osvaldo Jørgensen Talk-Page 01:24, 12 February 2020 (UTC)

Support the original proposal as stated; no need for a stand-along stub given that GIF can accommodate it. Having a brief summary remain at Video alternative to GIF is inefficient, as it duplicaties the first sentence or two on the target page section. An appropriate section would be to create a new section within GIF#Animated GIF, which could then also incorporate the brief GIF#GIFs with sound single sentence. Klbrain (talk) 13:51, 12 February 2020 (UTC)

Comment Suggest deleting "GIF with Sound" section (which is misleading: there are no GIFs with sound), incorporating that material and Video alternative to GIF in a new subsection "Video alternatives" under "Alternatives to GIF". -- Elphion (talk) 18:05, 12 February 2020 (UTC)

  Y Merger complete. Klbrain (talk) 13:48, 10 April 2020 (UTC)

Removing the "GIFs with sound" section

I see no point in a section whose purpose is simply to restate that GIFs do not have sound, so I removed it. Do let me know if anyone objects. HamartiaProsciuttoPharos (talk) 22:21, 16 February 2020 (UTC)

Section "History" / first paragraph: wrong word?

@ Metaeducation
In: GIF#History / first paragraph, the second sentence read:
{I have bolded the questionable word in the second part of the following sentence.}
GIF became popular because it used LZW data compression, which was more efficient than the run-length encoding that formats such as those used by PCX and MacPaint, and fairly large images could therefore be downloaded in a reasonably short time, even with very slow modems.
I "stumbled" over this "that". Could it be, that it should have become "and"?
Because the sentence was much too long to be easily understood, anyway, I restructured and reworded the whole paragraph, in order to describe the things in chronologic sequence, without changing any information; at least this was my intention. But after having restructured it and compared it to the original I still wonder whether I have put all the information from the original correct, especially, because I still wonder about this "that.".
Please ping me. Steue (talk) 07:21, 28 October 2020 (UTC)

@Steue I agree that the "that" makes the sentence hard to read, so I simplified that sentence. Your chronological rewrite, however, obscures the important point: the earlier wording has the right elements in the right order. -- Elphion (talk) 14:53, 28 October 2020 (UTC)

@Elphion: Thank you for clarification. At least now the content is clear and understandable.

However, now the words are no longer links, as they were before.

I, personally, prefer to put facts as chronologic as possible and in short sentences, because this makes everything easier to grasp, especially for all the many readers for whom English is not their mothertongue.

Just to understand why you answered although I wrote to U:Metaeducation, and, of course, only if you would like to disclose this: Are you the author of this paragraph and are using a different username or is it, that you know the facts good enough to tell how the sentence has to be?

Please ping me. Steue (talk) 03:08, 30 October 2020 (UTC)

I responded because I watch this page and you pointed out a passage that needs clarification. -- Elphion (talk) 03:33, 30 October 2020 (UTC)

Dictionaries, years of the editions?

In: GIF#Pronunciation_of_GIF / second paragraph there are mentioned a lot of dictionaries.
I would appreciate, if:

1. at each dictionary there would be mentioned the year and
2. if the dictionaries would be sorted by year.
   

This way one could see, whether there has been a kind of developement and who might have been following whom.
Please ping me. Steue (talk) 09:00, 28 October 2020 (UTC)

@Steue — This would be overkill, bordering on WP:OR. The dictionary references serve to show that both pronunciations are current, and that's what matters. If you have a WP:RS tracing the evolution of the usage, that would be an appropriate addition. But it is not our job to dictate (or even to suggest) "correct" usage. -- Elphion (talk) 14:58, 28 October 2020 (UTC)

@Elphion, it seems that you misinterpreted my intention. I do not intend to dictate or suggest anything. My intention is to find out whether there was a developement of some kind or not, and to get this made visible easily. And in case there was, it may be interesting to someone else als well.

If you, personally, are satisfied with what there is in this article, that is your decision; and I do not intend to evaluate or invalidate this. But you have no right to force your limitation onto all the other readers and to barr more information.

Please ping me. Steue (talk) 02:19, 30 October 2020 (UTC)

No change in my response: a reliable source for this would be fair game. -- Elphion (talk) 03:31, 30 October 2020 (UTC)

Empty.gif

The LZW sequence of Empty.gif consists just of one byte 0x44. The minimum code size for this LZW sequence is 2. Decoding that works only if the decoder adds another byte with the lowest bit set (e.g.: [0x44, 0x01]). The decoder now works as follows:

• Read the first 3 Bits from the LZW sequence --> 4
• 4 is the clear code. So the LZW state is reset.
• Read the next 3 Bits form the LZW sequence --> 0
• 0 is the colormap entry for the only pixel in Empty.gif.
• Read the next 3 Bits from the LZW sequence --> This would need the next byte from the sequence, but that does not exist.
• If the next byte would have a value with the lowest bit set (such as 0x01) then reading 3 bits from the LZW sequence --> 5
• 5 is the end code, so the LZW decoding is finished.

I have tested several GIF files and Empty.gif is the only GIF where the LZW decoder needs to read beyond the sequence. In all other GIFs I tested the LZW sequence ends with an end code and there is no need to go beyond the end of the LZW sequence. So either Empty.gif is not a correct encoded GIF or there is something missing in the explanation. In Wikipedia is also Blank.gif, which is encoded as

47494638 39610100 01008000 00ffffff 00000021 f9040000  GIF89a.............!....
0000002c 00000000 01000100 00020244 01003b             ...,...........D..;

Empty.gif is encoded as

47494638 39610100 01008000 00000000 ffffff21 f9040100  GIF89a.............!....
0000002c 00000000 01000100 00020144 003b               ...,...........D.;

You can see that Blank.gif uses an LZW sequence of [0x44, 0x01] which contains also an end code. -- Hans Bauer (talk • contribs) 10:35, 19 March 2021 (UTC)

You are correct: Empty.gif is not coded correctly and should have a 2-byte sub-block to include the full 3 bits for the stop code, exactly as Blank.gif does. Many decoders will ignore a screw-up like this if the stream contains enough data to fill out the pixels for the area described in the image descriptor. Some will even assume pixel values of 0 to the end of the image if the stream ends prematurely. I've removed the code readout for Empty.gif: it's not only incorrect, it contributes nothing to the discussion. -- Elphion (talk) 20:04, 19 March 2021 (UTC)

PS: The stop code is somewhat superfluous for GIF files (as opposed to, say, LZW-encoded text streams), since the decoder knows in advance how many pixel codes there should be. As I indicated above, many (probably most) decoders won't blink too hard if the stop code is missing (as it effectively is in Empty.gif, which simply stops after the last data byte). But both the 87a and 89a specs say that the stop code "must be the last code output by the encoder." -- Elphion (talk) 20:47, 19 March 2021 (UTC)

Application block for animated GIFs

A recent edit by user FaKen2021 claims that the application extension block added by Netscape to signal a repeating animation has an additional field for the length of the application name field. The 89a spec is quite explicit about the format of the application block, and it contains no such length field. It is possible for an application to fudge this, but a complying parser would not read it that way. Animated GIFs I have examined do not include such a field. -- Elphion (talk) 01:32, 20 April 2021 (UTC)

Apologies -- I misunderstood the edit because the description of the fields differed materially from the spec's definition. I have reinstated the edit and changed the annotations to conform to the spec. Thanks for catching the error in the original description. -- Elphion (talk) 02:00, 20 April 2021 (UTC)

GIF Spec

Danbloch (talk · contribs) removed the link to https://www.w3.org/Graphics/GIF/spec-gif89a.txt, claiming that it is not the GIF spec. This is the document that has been circulating for decades as the GIF spec, and it is so labeled at W3C. The link should be restored. -- Elphion (talk) 22:16, 27 July 2021 (UTC)

@Elphion: Sorry, you're quite right. I've reverted my change. Dan Bloch (talk) 23:34, 27 July 2021 (UTC)

Thanks. -- Elphion (talk) 23:51, 27 July 2021 (UTC)