DR800 updating metadata externally

[Mr. X]

Is there anything that holds global.db and the various metadata.db databases open while the DR is in USB client mode connected to a PC? I'm thinking the Calibre plugin could be customized to use sqlite to provide the metadata when copying books over, cutting down on indexing time and allowing higher quality metadata (e.g. the image the user provided as the cover not the first page of the document).

[Mr. X]

Alternatively, is OPF file parsing on the timeline for future enhancements? Calibre can also output the book, a cover jpg, and a opf metadata file that would be much faster to parse when available...

[Gertjan]

Originally Posted by Mr. X

Is there anything that holds global.db and the various metadata.db databases open while the DR is in USB client mode connected to a PC?

Certainly not. The SD card is unmounted from the devices OS before it is exported over USB so applications on the PC are free to access and alter the databases. This is what the (now defunct) Windows Companion software did for moving files and folders to retain annotation. Of course, the stability of the device can be affected by errors made in external applications.

[Shaggy]

Yeah, I think this goes back to even the iLiad days where you had to be in the Content Lister in order to connect to the PC, you couldn't have a document open. The general idea is that you don't want to let the device and the PC have access to the same data at the same time... bad things can happen. I'm pretty sure every firmware they've released since 2007 or so will make sure that the PC has exclusive access to any exported filesystem.

[Mr. X]

Originally Posted by Gertjan

Certainly not. The SD card is unmounted from the devices OS before it is exported over USB so applications on the PC are free to access and alter the databases. This is what the (now defunct) Windows Companion software did for moving files and folders to retain annotation. Of course, the stability of the device can be affected by errors made in external applications.

Cool. My plan was to wait for the updated libermetadb code to be posted (I see the schema version is 0.6 now) and steal most of the logic for touching the database out of there, just getting the values from calibre instead of scanning the card...

[Mr. X]

Oh- one more question I had was if the thumbnail blob has to be a .png or if .jpg is also allowed?

[Iñigo]

Originally Posted by Mr. X

Oh- one more question I had was if the thumbnail blob has to be a .png or if .jpg is also allowed?

They are saved as png data.
You can select the data from thumbnails table and and just use or save as .png file, no need for any modification.

[inigo@inigo eReader]$ sqlite3 global.db
SQLite version 3.6.20
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .schema thumbnails
CREATE TABLE thumbnails (
  file_id            INTEGER PRIMARY KEY NOT NULL,
  thumb_data_mini    BLOB,
  thumb_data_small   BLOB,
  thumb_data_medium  BLOB,
  thumb_data_large   BLOB
);
CREATE TRIGGER fki_thumbnails_file_id
BEFORE INSERT ON thumbnails
FOR EACH ROW BEGIN
	SELECT RAISE(ROLLBACK, 'insert on table "thumbnails" violates foreign key constraint "file_metadata" (file_id)') WHERE (SELECT file_id FROM file_metadata WHERE file_id = NEW.file_id) IS NULL;
END;
CREATE TRIGGER fku_thumbnails_file_id
BEFORE UPDATE ON thumbnails
FOR EACH ROW BEGIN
	SELECT RAISE(ROLLBACK, 'update on table "thumbnails" violates foreign key constraint "file_metadata" (file_id)') WHERE (SELECT file_id FROM file_metadata WHERE file_id = NEW.file_id) IS NULL;
END;
sqlite> select thumb_data_small from thumbnails where file_id == 2515;
�PNG


sqlite>

Iñigo


EDIT: ok, I'm reading carefully now... you asked if jpeg could be used besides png. Sorry.

[Mackx]

Originally Posted by Mr. X

Oh- one more question I had was if the thumbnail blob has to be a .png or if .jpg is also allowed?

The code of the function get_thumbnail_from_data() in filemodel.c (DR800 firmware) suggests that only PNG is supported at this moment.