A few people pointed out IDM in my FDM review, so I decided to check it out.

First up, I must say the initial interface is rather disappointing.
Here's my criticisms:

• The "Time left" column seems to be totally wrong here on my test download (connection speed is stable, but the time is stuck at "3 seconds" when it's quite obvious that it's going to take around 20 seconds to complete)
  Note, this test download doesn't support resuming (I made it that way).  For files that support resuming (Accept-Ranges header), it seems to work properly.
  
• The status window is very basic - pretty much just displays the download progress and shows nothing about headers sent etc.  Can't be docked to the main window either.  It does show how much each connection has downloaded at least, I guess.
  
• The "Add URL" dialog is pretty retarded - why does it come up with 2 dialogs?  Can't it just use the 2nd one for all the info?
  
• Even on the 2nd Add dialog, there's very little options.  No options for referrer, number of portions to split, can't manually specify mirrors/alternative URLs, no proxy selection etc.  Very little control over the download at an individual file level.
  
• The speed is a lie.  IDM claims that I'm downloading at ~57-58KB/sec on my 512Kbps connection.  Certainly within the maximum limit, but I know for sure I can't get such a fast sustained transfer speed, as every single other app maxes out at ~52-53KB/sec.  Just to verify that IDM doesn't have some magical component in it, I test downloaded a 2.2MB (exactly 2,332,126 bytes) file using IDM and Flashget, and timed each.  Both took slightly longer than 46 seconds (around 46.5s), though IDM claimed speeds of 57KB/sec whereas FlashGet claimed 52KB/sec, so it's quite obvious that the real transfer speeds are very similar.  Doing a calculation, you get around 49.5KB/sec, but then, that includes overhead such as initiating the download etc, so the Flashget speed seems more accurate (plus my other applications display the same thing).  Used 2 connections for both IDM and FlashGet.
  
• IDM doesn't preallocate space for the download on the destination drive - instead, it saves to a temp directory, and even then, doesn't do any preallocation.  This is bad for a number of reasons:
  1) Obvious overhead of moving the file after the download completes (this won't occur if you have everything on the same drive).  But even on the same drive, because it doesn't preallocate, it's forced to save every connection to a separate file, which means it has to do a concatenation (rewrite the entire file) after the download completes.
  2) Preallocation assures that there won't be an issue of running out of free space
  3) Probably insignificant, but fragmentation issues.
  
• IDM uses the AppData folder, thus more difficult to make a portable version.
  
• No multi-proxy support.  Furthermore, no SOCKS proxy support (FDM also suffers from lack of SOCKS proxy support - forgot to mention it in previous thread)
  
• Surprisingly, despite being the most basic compared with FlashGet and FDM, it uses the most RAM, though it doesn't really use that much to be of any real significance.
  
• You're limited to 16 connections.  You could argue that there's little point in having more, but I can point out a number of specific cases where it does help.  Either case, why put the artificial limit there?  What's worse is that you're forced to use a number which is a power of 2.  At least IDM isn't silly enough to go overboard with connections if you ask it to use 16 on a small file.
  

Overall, to be quite honest, I see little justification in going for this app.  FDM offers more features, works better internally, and is free.

(This post was last modified: 09/02/2009 04:22 AM by ZiNgA BuRgA.)

I use Crypt Load.

I never liked Flash Get, or any of the others I've tried...

(This post was last modified: 09/02/2009 11:29 AM by Kana.)

feinicks Wrote:

ZiNgA BuRgA Wrote:[list]

The "Time left" column seems to be totally wrong here on my test download (connection speed is stable, but the time is stuck at "3 seconds" when it's quite obvious that it's going to take around 20 seconds to complete)
Note, this test download doesn't support resuming (I made it that way).  For files that support resuming (Accept-Ranges header), it seems to work properly.

don't know why you get that. Its shows me a near about accurate time always. Not saying 100% accurate, but that is in any case false.

Have you tried this with a file which doesn't send an Accept-Ranges HTTP header, but does send a Content-Length header?
It's a bit weird - I might re-try it.

feinicks Wrote:

ZiNgA BuRgA Wrote:

The status window is very basic - pretty much just displays the download progress and shows nothing about headers sent etc.  Can't be docked to the main window either.  It does show how much each connection has downloaded at least, I guess.

You can. While downloading, click on the advance view. It shows all the connection and recieved... never really paid attention to it however.

Yes, I do have the Advance view open.  It still doesn't show headers - only shows progress.
Still can't dock it to the main window...

feinicks Wrote:

ZiNgA BuRgA Wrote:

The "Add URL" dialog is pretty retarded - why does it come up with 2 dialogs?  Can't it just use the 2nd one for all the info?

What? Which 2 boxes? Unless you mean one for adding the URL and the second one specifying where you save the download. It is meant to be integrated into the browser, due to its "Dumb user" friendliness. Ideally, you shouldn't have have to add a URL manually. And even if you have to, it shouldn't be a pain to do that. When grabbing from the net, you'll get only one.

That's kinda silly...  The other download managers just have one dialog, then when you add an URL from the browser, it just fills the URL textbox in for you.

feinicks Wrote:

ZiNgA BuRgA Wrote:

Even on the 2nd Add dialog, there's very little options.  No options for referrer, number of portions to split, can't manually specify mirrors/alternative URLs, no proxy selection etc.  Very little control over the download at an individual file level.

For most of the targetted users and for that matter, users, this is not really required. Exceptions are always present.

But it still lacks the option.  FDM has a simply interface too, but clicking on Advanced, gives you all these options.

feinicks Wrote:

ZiNgA BuRgA Wrote:

The speed is a lie.  IDM claims that I'm downloading at ~57-58KB/sec on my 512Kbps connection.  Certainly within the maximum limit, but I know for sure I can't get such a fast sustained transfer speed, as every single other app maxes out at ~52-53KB/sec.  Just to verify that IDM doesn't have some magical component in it, I test downloaded a 2.2MB (exactly 2,332,126 bytes) file using IDM and Flashget, and timed each.  Both took slightly longer than 46 seconds (around 46.5s), though IDM claimed speeds of 57KB/sec whereas FlashGet claimed 52KB/sec, so it's quite obvious that the real transfer speeds are very similar.  Doing a calculation, you get around 49.5KB/sec, but then, that includes overhead such as initiating the download etc, so the Flashget speed seems more accurate (plus my other applications display the same thing).  Used 2 connections for both IDM and FlashGet.

I disagree. I my self am running a 512kbps connection and the average download speed I get with: Firefox built-in Downloader (55-56kbps), FDM (58-60kbps), Flashget (55-60kbps) and IDM (62kbps-65kbps), made me choose IDM.

And I assume you've measured it?  A 512Kbps connection cannot exceed 64KB/sec, and it's extremely amazing if you get that figure, since that is the maximum burst speed - something you'll never get over a sustained transfer.  Line quality does play a role in what speeds you can get, which would explain why you're getting faster speeds than I am, however 62-65KB/sec is absolutely absurd on a 512Kbps connection.
Have you timed it?  You still haven't made a point against my statement that the speed is a lie...

If you think about it, there's really nothing magical a download manager can do to increase speed, especially when you're already maxing out your bandwidth.  The TCP and HTTP standards are defined, so whatever it does, IDM has to operate within these bounds.  You can do minor tweaks to the TCP handling by your OS, however this is a system level change which affects all applications, unlikely to be done by a download manager - and even then, these typically don't have much noticable effect.  For HTTP, there is really nothing to tweak (send a smaller request header?  Will save a few bytes of transfer, but that's it)

feinicks Wrote:

ZiNgA BuRgA Wrote:

IDM doesn't preallocate space for the download on the destination drive - instead, it saves to a temp directory, and even then, doesn't do any preallocation.  This is bad for a number of reasons:
1) Obvious overhead of moving the file after the download completes (this won't occur if you have everything on the same drive).  But even on the same drive, because it doesn't preallocate, it's forced to save every connection to a separate file, which means it has to do a concatenation (rewrite the entire file) after the download completes.
2) Preallocation assures that there won't be an issue of running out of free space
3) Probably insignificant, but fragmentation issues.

How wrong! Open up (My) Documents. You will find a new folder Downloads. Opening that will give you more folders: Music, Compressed, Programs, Videos and Documents. IDM creates this structure. As per your download types, the files are saved on varying locations; for instance, all RARs go to Compressed, all .exes go to Programs etc.

You've misunderstood me there.  Preallocation is different to where the file is saved.

I'll give you an example to help explain things.
Let's say your "My Documents" folder is on drive C:, but you're saving your file to drive D: (option specified in the Options dialog).  Let's say it's a 2GB file, but you've only got 1.5GB free on drive C:, but 10GB free on drive D:, which is why you're saving it to drive D:.  IDM will temporarily store the file on drive C: while it's downloading and probably end up stuffing up because you don't have enough space on C:.
But let's assume wee do have enough room on C:.  What happens?  IDM writes the entire file to C:, then after the download finishes, it has to read, and then write, another 2GB to drive D:, since it needs to reconstruct the file.  There's obvious overhead.
It's even worse if it's on the same drive - it has to perform a concatenation of parts on the same drive, which means a MUCH slower complete time because of disk seeking overhead.
Also, if you have an SSD/flash drive, means more writes = shorter disk life.

feinicks Wrote:

ZiNgA BuRgA Wrote:

IDM uses the AppData folder, thus more difficult to make a portable version.

should you need it: http://www.dl4all.com/portable/5843-inte...-5.12.html

Link is blocked here at work, but I'm sure a portable version is available.  Just saying it's more difficult to make.

feinicks Wrote:

ZiNgA BuRgA Wrote:

No multi-proxy support.  Furthermore, no SOCKS proxy support (FDM also suffers from lack of SOCKS proxy support - forgot to mention it in previous thread)

Never found that to be a problem.

Depends on your usage.  The average person won't need it, but then, does the average person need a download manager?

feinicks Wrote:

ZiNgA BuRgA Wrote:

You're limited to 16 connections.  You could argue that there's little point in having more, but I can point out a number of specific cases where it does help.  Either case, why put the artificial limit there?  What's worse is that you're forced to use a number which is a power of 2.  At least IDM isn't silly enough to go overboard with connections if you ask it to use 16 on a small file.

As you said. Its highly unlikely that anyone will need more than 16. Anymore would completely clog the network. Plus, IDM tends to be a background downloader, so as to not severely hamper your internet browsing speed.

Lack of flexibility cannot be considered an advantage however.

feinicks Wrote:In fact, IDM far from the best. No Download manager is. All are eventually bound by the restrictions of the uses connection.

The point of these reviews is to see which works the best :P


Thanks for the feedback!

(This post was last modified: 09/02/2009 08:47 PM by ZiNgA BuRgA.)

FlashGet for me. I use it for everything, http, ftp, RS, MU, MS downloads, even the quick torrent when i cba opening utorrent.