I have commited general explanations for this problem, in bug# 98565. Essentially all publicly exported elf-libraries in libpath have to set this field, in order to support versioning and to be linkable and it is a desirable practice altogether. I'll commit also a patch (taken from mandrake), which solves this problem.
Created attachment 63077 [details, diff] Patch to solve the problem with the missing SONAME-field in ffmpeg-libraries Patch to solve the problem with the missing SONAME-field in ffmpeg-libraries
Looks ok, could you please push it on upstream or want me to do that?
excuse me, i have ovelooked the email notification somehow. i think it would be better, if you file this upstream, as i simply noticed this problem and found a patch, which worked for me, so i posted it here. on the other hand i think it will be easier for you to push it upstream as a gentoo-dev.
Made upstream accept a patch to address the issue. Hopefully will be a release soon.
This should be fixed in 20051216 snapshot.