Writing tags corrupts DASH-encoded files

[GoogleCodeExporter]

I have noticed that using mp4v2 to write tags to a DASH-encoded MPEG-4 file 
corrupts the file. For more info about DASH, see 
http://en.wikipedia.org/wiki/Dynamic_Adaptive_Streaming_over_HTTP .

What steps will reproduce the problem?
1. Get a DASH-encoded file, e.g. this one from Youtube: http://goo.gl/vs6E0x
2. Verify that the file plays correctly in a DASH-compatible player such as VLC.
3. Run the following command to add an artist tag to the file: "mp4tags -a 
artist videoplayback.mp4".

What is the expected output? What do you see instead?

After running mp4tags, the file should still be intact and playable. However, 
no player (including VLC) seems to be able to play the file anymore, i.e. it 
appears to have become corrupted. The artist tag still seems to have been 
successfully written though.

What version of the product are you using? On what operating system?

Revision 504 on Windows XP SP3.

Please provide any additional information below.

Using Visual Studio 2008 Professional to compile, in the 'Debug Static' 
configuration.

Original issue reported on code.google.com by tdebaets on 11 Jan 2014 at 8:28