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dburg -> RE: WHY Packet write (2/17/2004 10:27:08 PM)
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The purpose of packet-writing on rewritable media is to better you the space offered. With multi-session, if you suppress an existing file when writing a new session, you do not re-gain the space of this file. With packet-writing on RW media, you regain this space. The problem with multi-session recording is that once your disc is full, you have to erase all the content to be able to use it again. With packet writing, you can select what you want to delete.
Also, with multi-session you waste medium space for multiple start and end of track (several dozen of Mb on a CD if I remember correctly). With packet writing you have a single track on the medium.
Basicaly, the concept behind is that multi-session is a write-once technology. You burn, it's here, for ever. The packet-writing is a random-access (non-sequential), rewritable, technology. You write, you delete, you move, ...
The problem with packet writing is that it is quite more complex than the sequential writing approach of multi-sessions. Additionally, CD mastering (eg., multi-session recording) is possible in a pure user mode application (Nero for instance does not require any driver on an NT/2k/XP system to burn). Packet-writing is implemented as a file-system driver. Yes, a driver, something that runs in kernel mode.
If you trigger a bug in a CD mastering application, you will likely loose the work you where doing in this application, and maybe the access to your device. But your system is still responding. If you trigger a bug in a packet-writing driver, you are likely to screw your entire system. You don't want to do that, do you?
Well, with InCD 4, Ahead Software attempted to take steps:
- in all NT system, most of the driver work is done at user level thanks to a technological innovation (which I will not detail, no no, I won't tell you the magic). This mean that if you trigger a bug, you are likely to cause trouble to user mode part of the driver. You don't screw your all system, but InCD will be disabled until you restart your computer.
- there is still a reduced size driver part (Windows operating system architecture does not allow pure-user mode drivers :-/). To better track bugs in this part, especially the bugs that occurs to you, our users, Ahead is working together with Microsoft in the Windows Error Report program. These are the reports you sent to Microsoft when your system or an application crash under Windows XP (and newer).
(As this post is getting really long I will stop here - probably some people wants to add comments.)
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