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Data layout on BD-ROM disc (and other media too)


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Hello. Although being a long-long time user of DVDDecryptor and its current legacy, I only came to this forum to ask a question. :)

Hopefully the LUK or someone else could help me. Many thanks in advance!

For my program, I need to have a function, that given the sector LBA would return a layer number this sector is located on. Mainly, for BD media, say a regular double-layer BD-ROM disc.

The layer bounds, specifically LUA/FUA values can be obtained from the disc structures. However I do not understand how the data is distributed or padded. Let's say that the disc contains two layers, the data zone of each layer is 1000 sectors in size. The total capacity of the disc (as returned by read_capacity) is 1500 sectors. So, how is the data located:
a) 1000 sectors on layer 0, 500 sectors on layer 1
b) 750 sectors on layer 0, 750 sectors on layer 1
c) something else?

Any pointers are very welcome.

On another note, my understanding is that this task is also somewhat non-trivial for DVD PTP. Any information would be welcome as well.




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For dvd, you'd just look at the layer break position and anything beyond that is on L1. Layer jump recording could be a pain to deal with!

For BD, as the you're meant to treat them as single layer and there are now disc with 4 layers, it's more complicated.
If you know the number of sectors available on each layer, I'd say you add the up until you reach the required lba. It should fill a layer before moving on to the next and there's no way to move the layer breaks like there is on OTP DVD.

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