Hi, I am working on a matlab file reader/writer. Since matlab uses zip to compress variables I was thinking I could use the boost filtering streams with the zip filter to handle that. The use case is that there are zipped blocks inside the file, i.e. not the whole file is zipped but just parts. I am not sure how to handle that with boost, since I would need to start/stop zipping/unzipping at almost arbitrary points in the file. Also I have trouble working with filtering streams at all. As a baseline test I started substituting the fstream I was reading from with a boost filtering istream onto which I pushed the fstream. Reading works fine for a while and then breaks. What I noted is that the fstream tellg always lags behind the actual number of bytes read. also using the fitlering streams tellg breaks the whole stream. also seeking does not seem to work with the filtering stream. I need to seek quite often. seeking only happens when not unzipping. I tried seeking on the fstream instead. that worked up to some point(as stated above). I fear the seeking on the fstream breaks the filtering stream, but seeking on the filtering stream doesn't work. If anyone has pointers that would be great. Best Daniel