[Tracker] Write-back data & default/dummy data

[Martyn Russell <martyn lanedo com>]

Hi,

After this mornings meeting, we briefly discussed libstreamanalyser 
(LSA) and again, this topic of writing data back to files and setting 
default data where it doesn't exist in the file's metadata was brought up.

So I am bringing this discussion here to get some ideas/feedback so we 
can extend the meeting on Wednesday to discuss it. Ivan, Mikael, Philip, 
Jurg and Carlos, I would appreciate any comments you have here especially.

So here is the common problem:

1. If a file doesn't have ALL the metadata associated with it that we 
would normally expect (for example Video Title), should we set a default 
value for these cases?

2. If we do have a default value to set, should we write this back to 
the file?

I think if we plan to do this, we should have some "fix-up-data" 
solution somewhere which we can apply after the actual data is extracted 
to keep this part separate. This is currently a bug in 0.6. because we 
use data like the file name for video title and if the file name 
changes, of course, we don't update the video title. So we should 
consider having to do that too.

The write back issue is also being discussed later (Thursday I believe) 
this week as to how or who should be doing this task. In 0.6. it is done 
by the applications. Should it be done by Tracker? If so, what approach 
makes sense here? Considerations here include how would LSA do it if we 
switched or used it partially at some later date? Changes to the files 
also mean monitor events, which means reindexing automatically (so some 
signal blocking might be needed).

Comments welcome,

--
Regards,
Martyn