proxy_cache - Is there a way to cancel file caching from header filter?

[Anatoli Marinov]

Hello,
Is there a way to cancel file caching from header filter?

I am using nginx as a reverse proxy and proxy_cache for caching and this 
configuration serves flv files.

Standard flv module cannot work with proxy_cache so start= argument is 
not understand by the nginx. There is other internal server (typically a 
cloud of them) that understands the argument and return a chunk from the 
file - starting from desired position. After this file is received from 
the nginx by its upstream it will be cached.

These chunked files should not been cached because they do not contain 
the whole content of the original file.
So I have written new header filter and in this filter for given file I 
can take a decision  to cache it or not. By default proxy_cache will 
cache this file so can I cancel this?

Anatoli Marinov