Sergej, that created the DDP plugin for Reaper has created a marker list window that will enable us to type in the codes, but Cockos hasn't put it in the latest Reaper build yet. Maybe it will come soon. For now, you can look in the render dialog under DDP, and click the ? for instructions.
# markers recognize this keys:
- "ISRC" number for audio track
- "TITLE" or without a key for track's title
- "PERFORMER"
- "SONGWRITER"
- "COMPOSER"
- "ARRANGER"
- "MESSAGE"
MARKERS EXAMPLE:
1. "#Intro|ISRC=012345678901"
2. "#Second track|ISRC=012345678902"
3. "!"
4. "#TITLE=Third track|ISRC=012345678903"
5. "!"
6. "#Last track"
7. "@My first album|PERFORMER=A good band|EAN=0123456789012|GENRE=Pop|LANGUAGE=English"
Here's a screenshot of a maker that has ISRC for DDP
Reaper can't burn a DDP yet, but I'm hoping they will consider this.
There is a request for ISRC codes to be implemented for Reaper.
You can vote here
http://forum.cockos.com/project.php?issueid=2398
Hope this helps.