I noticed the following after updating libffado. The cache file in this situation is updated with the new version.
So, just for fun (to test the caching code once more ...) I compared two versions and there were a few differences.
Further investigation gave:
The values are different when the is written for the first time vs. when the cache is written otherwise (e.g. after an update)
File '0000000003050704.xml.1' is written with the same values after every new discovery of the device, file '0000000003050704.xml' is written after deserialization and serialization.
If you compare the two files, there are 4 different m_streamFormat values.
Hope this helps to make libffado a little bit better ;-)
P.S.: If this is not a bug then sorry fow the noise.