Some of the news in our upcoming Helium version, 13, are now official.
Read more about them from the link below:
This relates to the amount of data that needs to be written and the file format. Optimizations can most likely be done for specific cases and file formats.
For MP3 files, picture data can be replaced with padding bytes which will remove pictures but not reduce file size without the need to rewrite the entire file. The same can be achived for FLAC files also.
For WMA files this is not possible since saving is "black-boxed" (handled by Microsoft)
@Sven: Helium 13 will most likely come with hugh speed improvements to FLAC tagging.
For scenarios when the tags are changed so the resulting tag wil lbe less or equal the current size plus padding, the whole file will not need to be rewritten.
The same applies to removing of pictures. MP3 files will most likely use the same logic.
This is something we are currently doing tests on so it is not yet 100% complete. If you are interested in testing it directly, please let us know.
@Chris: Please send us a notification via support.imploded.com and we will let you know more.