PSA: Filenames for web experiments can be case-sensitive

AKrishna — Mon, 26 Feb 2024 16:54:14 GMT

Hi all,

I've run into this issue before and I really should know better by now, but I just spent 20 minutes googling and couldn't find an answer, so I thought I'd write up a problem I had and its solution for posterity.

I set up an Inquisit Web experiment which included media files (specifically mp4s, although I didn't test whether other types of media such as pictures were also affected). It ran fine locally, but when I tested it from the Inquisit Web launch page, the script crashed when loading the media ("Relax_1.mp4"). The error message was: "Invalid media 'Relax_4.mp4'." (Code 0), followed by "Player Error 'Relax_1.mp4'. Resource could not be resolved. Failed to load source." (Code 0), and "Unable to load the media file '[redacted link to file]'. Failed to load media." (Code 63).

The solution was to change the Inquisit script from:
[code]<video RelaxationVideo>
/ items = ("Relax_1.mp4")
/ playthrough = false
/ size = (80%, 80%)
/ stream = true
</video>[/code]
to:
[code]<video RelaxationVideo>
/ items = ("relax_1.mp4")
/ playthrough = false
/ size = (80%, 80%)
/ stream = true
</video>[/code]

Note the case spelling in the /items attribute. This fixed the issue. Hope this helps if anyone has the same problem.

And hi, future me! Yes, you have had this problem before!

RE: PSA: Filenames for web experiments can be case-sensitive

Dave — Mon, 26 Feb 2024 16:54:14 GMT

+x[quote]

[b]AKrishna - 2/26/2024[/b]
Hi all,

I've run into this issue before and I really should know better by now, but I just spent 20 minutes googling and couldn't find an answer, so I thought I'd write up a problem I had and its solution for posterity.

I set up an Inquisit Web experiment which included media files (specifically mp4s, although I didn't test whether other types of media such as pictures were also affected). It ran fine locally, but when I tested it from the Inquisit Web launch page, the script crashed when loading the media ("Relax_1.mp4"). The error message was: "Invalid media 'Relax_4.mp4'." (Code 0), followed by "Player Error 'Relax_1.mp4'. Resource could not be resolved. Failed to load source." (Code 0), and "Unable to load the media file '[redacted link to file]'. Failed to load media." (Code 63).

The solution was to change the Inquisit script from:
[code]<video RelaxationVideo>
/ items = ("Relax_1.mp4")
/ playthrough = false
/ size = (80%, 80%)
/ stream = true
</video>[/code]
to:
[code]<video RelaxationVideo>
/ items = ("relax_1.mp4")
/ playthrough = false
/ size = (80%, 80%)
/ stream = true
</video>[/code]

Note the case spelling in the /items attribute. This fixed the issue. Hope this helps if anyone has the same problem.

And hi, future me! Yes, you have had this problem before!
[/quote]

Adding:
- For general background, all files names are automatically converted to all lowercase when they are uploaded to the web. This is done for cross-platform compatibility reasons (some file systems are case-sensitive, i.e. A.jpg and a.jpg are different files than can coexist in the same place, whereas others are not.
- In most cases, the casing in /items does not matter, since Inquisit will convert these to all lowercase when downloading, which happens before the script is executed on the client system.
- There are, however, edge cases: Here, the file isn't downloaded up-front, but streamed at runtime, and that is why the casing matters. Another ede case would be HTML files that read file names from <item> elements in your script.
- In terms of defensive programming, it is a good idea to always give file names in all lowercase.

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PSA: Filenames for web experiments can be case-sensitive

RE: PSA: Filenames for web experiments can be case-sensitive