Please note: This posting is just as a matter of record in case anyone has a similar issue now or in the future. Although this issue arose with a Nexus 7, I suspect similar issues (and solutions) apply to other Android devices.
To start with, I recently bought a Nexus 7 tablet. Overall a great device. As part of setting it up to my requirements I wanted to copy over a variety of files from my computer. The Nexus connects up via a supplied USB cable and appears as a device (not a disk) in Windows Explorer. MP3s and WMAs went across without a problem (just drag’n’drop in Windows Explorer), but other file types would not, with an error dialogue appearing stating “…file type is not supported on this device…” and giving the options to Skip, Skip All or Cancel.
Having researched this, I've come up with the following.
Note that this is a crude summary of a complex area just to give the flavour of the problem. It may not be technically 100%, but will give a feel for the issue.
Now, as mentioned above the Nexus does not appear as Removable USB Storage (e.g. a disk or facsimile thereof) in Windows Explorer and is not serviced using the same protocols. Instead MTP (Media Transfer Protocol) is used. With USB disks and the like Windows takes control of the device (e.g. a USB Flash drive), but with MTP Windows does not take control of the device. This is for two good reasons. Firstly the Nexus is a live computer plugged in to a USB port and so Windows cannot take exclusive ownership. Secondly, the storage made available for access externally by the Nexus (via the USB port) is just a segment of its overall storage that the Nexus is exposing externally (i.e. it is not a discrete physical or logical “disk” inside the Nexus).
So, to safely allow file copies and the like, MTP allows Windows (as the Initiator) to send requests and data (the files) to the Nexus (as the Responder) for the Nexus to do the necessary disk / file actions under its control.
The issue in transferring non-media files across is hinted at in the name of MTP itself (MEDIA Transfer Protocol). And it is Windows that is preventing the transfer (i.e. it believes that non-media files should not be allowed to go across), not the Nexus blocking the files.
As far as I know this issue is constrained to certain versions of Windows and Windows Media Player (there’s that word media again). In my case I am running Windows XP with WMP10. I am given to believe that upgrading to WMP11 should circumvent the issue. More information is available in the MTP Responder Development Guide [ available at http://www.microsoft.com/windowsembedded/en-us/develop/CE-MTP-Responder-Development-Guide.aspx ] in particular “File Transfer Messages” at the end of p28 and the table at the start of p29.
BUT there is an easier solution (as long as it is not too many files). Before copying simply rename the files to be transferred to an acceptable media type (e.g. rename manual.pdf to manual.mp3), then transfer the files across and then rename them back on the Nexus (e.g. manual.mp3 to manual.pdf).
Note that to facilitate the renaming on the Nexus a suitable app (e.g. equivalent of Windows Explorer) needs to be installed to access the folders on the Nexus. I use ES File Explorer, but there are a number of similar apps available.
To cut a long story short you cannot use windows files on a Linux System. Unless you know how to do it and if you can get Linux support for the above. So you need to Search Google for support of your Device and Windows Files
Dropbox speed depends on your upload speed connection.
A further option that I've now tried (at a small cost) is via a UBS OTG cable and a flash drive plugged into the Nexus via the cable
My UBS OTG cable arrived today (£1.29 off ebay), it is slightly loose in the microUSB socket on the Nexus, but I downloaded Nexus Media Importer (NMI) and it all seems to do the job.
I looked around at other apps on the Google Play site that provide some degree of USB OTG support, but although the others were free, NMI (at £1.88) was the only one I saw that made it clear that rooting was not required, plus NMI comes with an integrated file manager that works well enough for both media and other files.
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