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Subject: Re: CRC checks in codecs

Re: CRC checks in codecs

From: Nils Wallménius <nils.wallmenius_at_gmail.com>
Date: Tue, 29 Jun 2010 20:25:31 +0200

On Tue, Jun 29, 2010 at 6:37 PM, Dave Hooper <dave_at_beermex.com> wrote:
> 'How often do files just go bad' - well I guess part of the reason for the
> crc is that nobody really knows the answer to that. Ever downloaded a
> corrupted file from the internet, or a torrent with missing (unavailable)
> chunks? Without crc checking the frame, you could easily crash rockbox with
> malformed/garbage data, since I doubt all data is validated/sanity checked
> in all code paths. That's just vorbis though (which iirc actually does do a
> reasonable job of sanity checking most things along the way), other codecs
> might have less sanity checking -- do we do crc checking on mp3?  If not
> then, I suppose, we could remove it from vorbis also (and see who complains
> after the next release..)
>
> Or alternatively see if the crc loop could be optimised more perhaps?
>

I don't really download files very often but if crc checks would fail
often i think we would get quite some bug reports about glitches in
the sound or files that won't play depending on how the individual
decoder handles this. But i see your point so do you think a setting
that keeps it enabled as default would be ok or would you rather i'd
leave it alone.

I think at least the vorbis loop can be optimized a little but it
doesn't really change my opinion of this checking.

And as lear stated mp3 does it as well as a bunch of others.

Nils
Received on 2010-06-29


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