Messages in this thread | | | Date | Sat, 17 Nov 2007 22:58:10 -0600 | From | Robert Hancock <> | Subject | Re: [REQUEST] Option for skipping unreadable blocks on Video DVD |
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Tobias wrote: > If you are accessing a scratched Video DVD and the device cannot read it, the > process ends. > What about a more tolerant way to handle unreadable blocks. > Especially on Video DVDs single blocks are not that important than on data > dvds.
If the DVD player process ends from this, I'd say that's the fault of the player software not handling errors properly.
I think that if they are using the normal block layer accesses on the DVD device, there may be some retries that occur which are likely undesirable in this case since they will just stall playback. If they are using SG_IO to feed raw requests into the drive (which I imagine they need to do for CSS authentication, etc. anyway), then all error handling is passed up to the user application.
> > So is there a way that the kernel tells the device to skip these bad blocks?
We don't know they're bad until we try and read them. How long the drive will stall trying to read that sector before giving up and returning an error is up to the drive. I'm not sure if the MMC command set allows any way to tell the drive to give up more quickly or not..
-- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/
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