Problem transferring MP3s via VPN

[moeuf]

I wonder if anyone can shed some light on this...
While transferring MP3 files over a Virtual Private Network, my husband discovered that regardless of actual file size, 4 to 5MB of data was being transferred. After extensive testing, we've determined that dAP is the most likely cause, but we can't figure out what's happening. Even in a file of less than 1MB, 4 to 5 MB of data are transferred. The file size at the other end is correct. So where is the extra 3 to 4MB of data coming from? This doesn't occur with any other file type; just ones that dAP handles.
I've come to rely heavily on dAP, but if we can't resolve this issue, I'm afraid I'm going to have to uninstall it :( .
TIA for any insight/assistance
-moeuf

[xoas]

Re: Problem transferring MP3s via VPN

You could check an mp3 file from another source and try sending that. I do not know much about networking but I did find an article about Virtual Private Networks (VPN's) here: http://computer.howstuffworks.com/vpn13.htm. The full text talks about how VPN's work. In talking about part of the technology, known as tunneling, this article states:

Most VPNs rely on tunneling to create a private network that reaches across the Internet. Essentially, tunneling is the process of placing an entire packet within another packet and sending it over a network. The protocol of the outer packet is understood by the network and both points, called tunnel interfaces, where the packet enters and exits the network.

The article also mentions that the contents of the inner packet (in this case your mp3 file) are usually encrypted as another security feature. My guess would be that the extra MB being sent represent this outer packet which serves as a security protocol for the VPN and the extra encryption for the inner packet.In that case, you would find the same result for an mp3 file regardless of the program that created it. If you know that the situation is otherwise, you might provide some explanation as to how you are certain this is not the case.

Best wishes,
Bill Mikkelsen

[ChristinaS]

Re: Problem transferring MP3s via VPN

Are you using dAP to trasnfer files? like playing them from a remote drive?

In any case, I'd think it's more a matter of packet size as Bill mentioned. 4MB seems to be a regular buffer size for data transmissions. It is the standard buffer size for FTP, for SDP and quite likely for whatever you are actually using. Perhaps it can be configured.

Why is this an actual problem? Isn't the file in fact restoerd to the right size at the destination?

[moeuf]

Re: Problem transferring MP3s via VPN

The reason we're fairly certain that it's related to dAP is that we have not seen this effect when transferring other file types, such as image files.
In itself, the extra data transfer is not a problem (except that it slows down the works a bit). We are more concerned about understanding *why* it's happening only with these file types that are associated with dAP, as it seems to suggest that dAP is doing something naughty. :shocked:

[ChristinaS]

Re: Problem transferring MP3s via VPN

The reason we're fairly certain that it's related to dAP is that we have not seen this effect when transferring other file types, such as image files.
In itself, the extra data transfer is not a problem (except that it slows down the works a bit). We are more concerned about understanding *why* it's happening only with these file types that are associated with dAP, as it seems to suggest that dAP is doing something naughty. :shocked:

How is dAP (and do you mean the player or the entire dBpowerAMP set of programs?) actually involved in your transfer, this is what I don't understand.

[moeuf]

Re: Problem transferring MP3s via VPN

How is dAP (and do you mean the player or the entire dBpowerAMP set of programs?) actually involved in your transfer, this is what I don't understand.

That's just it...it isn't. Or at least it shouldn't be. I can see no reason at all why these files should entail such large data transfers. However, the only files that we are seeing this with are files associated with the player. We've experimented with this, trying the same transfers on systems without the player installed, and there is no excessive data transfer on those systems. On my own system, there is no excessive data transfer when transferring other file types. Thus, the only rational conclusion appears to be that the player is somehow associated with this extra data transfer. :confused:

[ChristinaS]

Re: Problem transferring MP3s via VPN

Could it be that in fact all that those files have in common is that they are audio files? AUdio files are much larger than image files or text in general.

I still don't understand what you are using to transfer those files on the network. Are you playing them? are you copying them using a straight copy and paste or drag and drop? is it FTP of sorts?

You'll have to really give a good detailed example of what you mean, because I'm at a loss to understand what the problem is.

When you check the properties of a file you get 2 values: actual size and size on disk. The size on disk will be determined by the file addressing scheme your system is using. Files are stored in blocks of a minimum size. A one line text file will take as much space as a much larger file simply because the minimum block size is 4K (in NTFS, for instance) and files are stored in multiples of 4k bytes.

[Spoons]

Re: Problem transferring MP3s via VPN

i'm not sure i understand what the problem is either. if "any" file is associated with dap you should see the files association in dap config : start-->programs-->dbpoweramp-->configuration-->file association

give us an example of the exact file name you are seeing that you think dap is associating it with.

[moeuf]

Re: Problem transferring MP3s via VPN

Could it be that in fact all that those files have in common is that they are audio files? AUdio files are much larger than image files or text in general.

We've compared the audio file transfers with image file transfers of similar size. What concerns us is not simply the size of the data transfer, but the difference between the size of the file and the size of the data transfer. Obviously a larger file will require a larger transfer of data. But two files of similar size should have roughly similar amounts of data being transferred, should they not?

I still don't understand what you are using to transfer those files on the network. Are you playing them? are you copying them using a straight copy and paste or drag and drop? is it FTP of sorts?

It's a VPN...I just drag and drop from a folder on my system to a folder on his.

You'll have to really give a good detailed example of what you mean, because I'm at a loss to understand what the problem is.

When you check the properties of a file you get 2 values: actual size and size on disk. The size on disk will be determined by the file addressing scheme your system is using. Files are stored in blocks of a minimum size. A one line text file will take as much space as a much larger file simply because the minimum block size is 4K (in NTFS, for instance) and files are stored in multiples of 4k bytes.

When I drag and drop a .jpg(not associated with dAP) of 2.1 MB from my system to his, the data transfer is approximately 2.1 MB. When I drag and drop an .mp3(associated with dAP) of 2.1 MB from my system to his, the data transfer is approximately 5 MB. dAP is not playing the song at the time of the transfer, nor is the song being played at his end at the time of the transfer.
I have checked size on disk against actual size, and there is only a few bytes difference; not enough to account for the vast disparity between the data transfer sizes.