[Docs] Typo in lossless webp test results page; noasm flag

[Joe Duarte]

Hi all,

Three things:

1) There's a typo in the Table 2 heading for the lossless test results here: https://developers.google.com/speed/webp/docs/webp_lossless_alpha_study

It says: "Average encoding average time for the compression corpora..."

I assume the correct version would drop the second instance of average, yielding "Average encoding time for the compression corpora..."

This is also a good time to nudge the powers that be that we need more data, with real-world devices. Some data on battery life impacts would be awesome as well.

2) In the guide for cwebp, there's a -noasm option, which "disables assembly optimizations". What's the purpose? If I'm a user trying to convert or create webp files, when do I care about disabling assembly optimizations? That sounds like a compiler flag, like a user telling cwebp not to unroll any loops while creating images. Is this a solution or workaround to another issue? Would we lose or gain anything other than wall time from using this option?

3) Other doc stuff: The FAQ is very helpful, but a little hard to find. Currently, it's in the Reference page, which is unexpected (I don't think people would consider an FAQ a reference, or look there for it). I humbly suggest providing a link to the FAQ on the homepage. The docs right now are a very mild case of what I provisionally call the GettingStartedDocSpecHelpRefGuideMore problem that you see on lots of software sites, where there are several links / main menu options that sound similar, like Docs, Learn More, Guide, and Reference. I think it probably paralyzes visitors for a moment as they try to guess which one will give them the info they want. The webp page is pretty good, but I'd move the FAQ out of the Reference page (or rename the Reference page the FAQ page or something.)

Cheers,

Joe

[Pascal Massimino]

Hi Joe,

On Sun, Oct 2, 2016 at 11:59 AM, Joe Duarte <songof...@gmail.com> wrote:

Hi all,

Three things:

1) There's a typo in the Table 2 heading for the lossless test results here: https://developers.google.com/speed/webp/docs/webp_lossless_alpha_study

It says: "Average encoding average time for the compression corpora..."

I assume the correct version would drop the second instance of average, yielding "Average encoding time for the compression corpora..."

thanks for spotting this. Should be fixed now. 

This is also a good time to nudge the powers that be that we need more data, with real-world devices. Some data on battery life impacts would be awesome as well.

Actually this study could use a refresh / re-match, since the code has evolved a lot (speed, compression efficiency, platforms) since.

 

2) In the guide for cwebp, there's a -noasm option, which "disables assembly optimizations". What's the purpose? If I'm a user trying to convert or create webp files, when do I care about disabling assembly optimizations? That sounds like a compiler flag, like a user telling cwebp not to unroll any loops while creating images. Is this a solution or workaround to another issue? Would we lose or gain anything other than wall time from using this option?

This is mainly used for testing the validity of the assembly optimizations and catching mismatch bugs: in the jenkins tests, we run commands (cwebp's, but also dwebp's) normally, and compare the output to the reference one issued by the '-noasm' flag. They should match bit-for-bit.

 

3) Other doc stuff: The FAQ is very helpful, but a little hard to find. Currently, it's in the Reference page, which is unexpected (I don't think people would consider an FAQ a reference, or look there for it). I humbly suggest providing a link to the FAQ on the homepage. The docs right now are a very mild case of what I provisionally call the GettingStartedDocSpecHelpRefGuideMore problem that you see on lots of software sites, where there are several links / main menu options that sound similar, like Docs, Learn More, Guide, and Reference. I think it probably paralyzes visitors for a moment as they try to guess which one will give them the info they want. The webp page is pretty good, but I'd move the FAQ out of the Reference page (or rename the Reference page the FAQ page or something.)

Thanks for the suggestion! The doc site has been part of a global overhaul with a common chart for menus and such, but let's see if we can put the FAQ on the site and more prominently visible...

hope it helps,

skal/