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Question: writing JPG files to FAT32 thumbdrive for TV slideshow

This has me a little stumped. Macs can read/write FAT and FAT32 formatted drives. I wanted to do a picture slideshow on a VISIO smart TV (E-Series) in another town using its built in slideshow feature from .jpg files on a USB thumbdrive. Visio manual states the USB thumbdrive must be formated FAT32 (my own Samsung TV will also take FAT and NTFS). The thumbdrives I bought, SanDisk 16 GB, came formated FAT32 (according to Get Info) so I just copied my .jpg images over, no folders. Plugging the thumbdrive into a VISIO smart TV (slightly different model than on at location) here at Costco (with thier help) for testing before leaving, and later into the VISIO TV at location, and neither recognized it, playing around with menus showed an empty drive. No problem on my Samsung TV. On location, Visio owner just copied files on thumbdrive over to another thumbdrive using a Windows computer and the Visio TVs then had no problem, so it wasn't any part of the filename or extension. I thought if one device could see files on a FAT32 thumbdrive, all devices could. Is the Mac doing something not quite standard in writing the .jpg files so Visio TVs just can't read/see them? I did eject thumbdrive before phyically removing. Is this just a problem with Visio TV having a very rudimentary OS?

iPhone 6, iOS 11.1

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Apr 22, 2018 1:23 PM in response to phillman55 In response to phillman55

When you write files to a FAT32 drive, the OS creates two files. One is the data fork (typically the actual data file) and another file to hold the resource fork data, which would normally be lost on the FAT32 drive's single fork file system. So, you end up with things like this:


puppy.jpg

._puppy.jpg


The second is the AppleDouble file of the saved resource fork. You don't see it from your Mac because it begins with a period, and any such file is automatically hidden.


However, the type of system you're referring to doesn't know anything about that and tries to display the ._puppy.jpg file because as far as it's concerned, it ends with .jpg, so it must be an image. That causes it to hang.


The Terminal command dot_clean will will remove these AppleDouble files.


Using an MS-DOS formatted USB flash drive as an example. Have the drive plugged in so its icon is available on the desktop. In Terminal, type:


dot_clean -mn


Put a space after the -mn. Don't hit Enter yet. Now drag and drop your USB drive's icon from the desktop into the Terminal window. It will fill out the correct path for you, similar to this:


dot_clean -mn /Volumes/FLASH\ DRIVE


I happened to use a flash drive that has the name "FLASH DRIVE". That's why the \(space) between the two words in Terminal.


What you've done is:


1) Entered the basic command

2) Added the command argument m, which means "Always delete dot underbar files." This is automatically done recursively (all folders and subfolders on the drive).

3) Added the command argument n, which means "Delete dot underbar file if there is no matching native file." Without it, Mac files on the DOS formatted drive such as ._Trash would be left behind.

4) Told it what drive to run this command on.


Now press Enter. It's done when Terminal goes to the next prompt. Dismount the drive and insert it in a Windows computer to confirm all ._ prefix files are gone. They should be. All .DS_Store files, I believe, still get left behind.

Apr 22, 2018 1:23 PM

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Apr 23, 2018 9:42 AM in response to Kurt Lang In response to Kurt Lang

Kurt,

Thanks, not being a neophyte, I follow you. However even on a Windoze 10 computer and using the command line, all the ._filename.jpg files are not shown. On the Mac, telling the finder to show invisible files (or in terminal), I see items such as: System Volume Information, .device info_ . . ., .fseventsd, .spotlight-100, .Trashes, but not ._filename.jpg files. Wouldn't these be hidden in a database file or folder so as not to confuse OSs that are just expecting a single fork? The Visio TV showed the thumbdrive as completely blank, it said there were no media files present, not that it was having problems with the resource fork files.

I've not had a problem before writing files to FAT and FAT32 thumbdrives to be read by various devices. This seems to to me, especially as my Samsung TV had no problem, to be a Mac - Visio TV problem.

Apr 23, 2018 9:42 AM

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Apr 23, 2018 10:13 AM in response to phillman55 In response to phillman55

I see items such as: System Volume Information, .device info_ . . ., .fseventsd, .spotlight-100, .Trashes, but not ._filename.jpg files. Wouldn't these be hidden in a database file or folder so as not to confuse OSs that are just expecting a single fork?

._xxx.jpg (or other other filename extension) will only be written if the file has a resource fork. Such as, if I copy old .tif images I created years ago with Photoshop CS6 or older to a FAT32 drive, those will always have a resource fork and will get ._ files created. But the CC apps dropped writing a resource fork, so .tif or .jpg files from the newer versions of Photoshop won't result in a ._ file being written.


These paired files, when they exist, are always right next each other so the OS can find them.


That the Visio sees nothing most likely means the only drive format it will recognize is NTFS. That's been the case in at least a few other similar topics here. What you'd have to do is put the images from your Mac onto the flash drive you want to view on the Visio. Take that drive over to the Windows computer, copy the images off, format it as NTFS, then copy the images back onto the flash drive.

Apr 23, 2018 10:13 AM

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Apr 23, 2018 10:39 PM in response to Kurt Lang In response to Kurt Lang

Thank again Kurt. According the to manual for Vizio (sorry for the spelling mistakes) they just will accept FAT32 (my Samsung TV will do FAT, FAT32, NTFS). I did do a test, on a Windows computer, copied the .jpg images off the thumbdrive, deleted the .jpg files on the thumbdrive, copied the .jpg files back to the thumbdrive. So if any ._filename.jpg files were there, they still were. I didn't reformat the thumbdrive. Now the thumbdrive worked just fine in a Vizio TV.

So, my main point here is there seems to be some problem with the combination of Mac written FAT32 thumbdrives and Vizio TVs (I've had no problems with Sharp and Samsung). You have explained a possible cause to the problem. If you're taking the thumbdrive to another location, be prepared for some problems, best to write the files onto the thumbdrive on a Windoze computer. But I think this should work and either Apple or Vizio need to make some changes.

Apr 23, 2018 10:39 PM

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Apr 24, 2018 6:01 AM in response to phillman55 In response to phillman55

I did do a test, on a Windows computer, copied the .jpg images off the thumbdrive, deleted the .jpg files on the thumbdrive, copied the .jpg files back to the thumbdrive. So if any ._filename.jpg files were there, they still were. I didn't reformat the thumbdrive. Now the thumbdrive worked just fine in a Vizio TV.

That is simply bizarre. I can't think why writing the .jpgs from Windows would work, and not from the Mac. They're the exact same files written to the same FAT32 formatted drive. Wish I could give you a clue why that made any difference at all, but it shouldn't have.


Glad you got them to work, though.

Apr 24, 2018 6:01 AM

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Apr 24, 2018 9:49 PM in response to Kurt Lang In response to Kurt Lang

That is simply bizarre. I can't think why writing the .jpgs from Windows would work, and not from the Mac. They're the exact same files written to the same FAT32 formatted drive.


Ah, this is more or less the reason for the original post. I did notice when this later 'test' thumbdrive was put into the Vizio, and the Costco employee selecting slideshow, I did see for a split second the Vizio showing a directory, including some of the Mac invisible files mentioned in a reply above.

Apr 24, 2018 9:49 PM

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Question: writing JPG files to FAT32 thumbdrive for TV slideshow