To say again, the problem here is that there is absolutely no guarantee that the user will store books in CC's folders. Any book not in the proper CC folder must be ignored. I am very concerned that this behavior will create no end of support problems because people won't understand why it doesn't "just work". And it won't "just work".
The above notwithstanding, I am willing to look at this, but to do so I need help. I don't have a device with an SD card, so I have no idea whether calibre can send to sd cards, and if so, what is in the metadata.calibre file. Could some brave soul with an sdcard-equipped device tell me:
- How does calibre's MTP driver distinguish between main memory and a card?
- Assuming that there are books on the SD card, does calibre put a metadata.calibre file on the sdcard? Where? In the root?
- Assuming that there are books in main memory, is there also a metadata.calibre file in main memory? Where? In the root? (That is where I see it on my devices.)
It would be most helpful if you can send me copies of the metadata.calibre files.
Note: if and when this function arrives, it will require an explicit choice to run it, similar to the "Find missing books" in CC today. The processing is complex and time consuming, so it can't be run automatically. Any new or changed book will require modifying the database, which will run at the same speed as metadata upgrades received over wifi.
Finally, I am curious about why people want this feature? It is purely an expectation of better performance, in that copying books over USB is faster? If so, does this advantage go away because of CC's import and the time taken to update metadata? It isn't obvious to me that a combination of sending over a cable and then importing into CC will be faster than simply sending to CC to begin with.