[LV2] Storing binary data chunks without duplication

Robin Gareus robin at gareus.org
Thu May 9 09:52:17 PDT 2019

Hi Stefan,

I can't offer a solution, but perhaps a hint:

On 5/9/19 5:37 PM, Stefan Westerfeld wrote:
> Ardour stores a new copy of each instrument chunk each time the user saves the session

When lv2_state_equal() matches the previously saved state, Ardour does
not save the state.

The problem however is that the plugin is asked to save state
this is compared: lv2_state_equal() and only on mismatch saved:

I guess the problem in your case is that new_from_instance() already
triggers saving the big external blob?

> Is there a way to save large custom binary data chunks into the 
> session without duplicating data on each save?
How about:

 - save the samples only once and treat them as external files that
don't change (much like external sample-banks):  use map_path, not

 - save the meta-data as LV2_ATOM__Chunk. As long as it doesn't change,
no new state will be saved.


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