From: Leo Izen <leo.izen@gmail.com>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] FFV1 slicecrc: "hashxx" instead of "CRC" for speed?
Date: Thu, 3 Nov 2022 09:01:32 -0400
Message-ID: <406a2b30-c7ac-c0fd-4354-61aa9791758d@gmail.com> (raw)
In-Reply-To: <20221026191302.GG4048598@pb2>
On 10/26/22 15:13, Michael Niedermayer wrote:
>
> CRC is not a random pick for error detection, CRC has specfic properties
> like for example that whole classes of errors are guranteed to be detected
> a random hash will not gurantee that.
> for example a properly designed 8bit CRC will detect every single 1 byte change
> always. a 8 bit hash like taking 8 bits from SHA256 will detect only 255 out of
> 256 1 byte changes
I'm a bit confused here, aren't there only 255 one-byte changes in the
first place? The 256th is when the byte remains unchanged.
That aside I don't believe xxhash is designed to be an error-correcting
hash, but rather one that's used for fast database lookup.
- Leo Izen (thebombzen)
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next prev parent reply other threads:[~2022-11-03 13:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-25 20:31 Peter B.
2022-10-25 20:37 ` Andreas Rheinhardt
2022-10-26 7:25 ` Kieran Kunhya
2022-10-26 7:58 ` Paul B Mahol
2022-10-26 19:13 ` Michael Niedermayer
2022-11-03 13:01 ` Leo Izen [this message]
2022-11-03 13:19 ` Nicolas George
2022-11-03 15:07 ` Leo Izen
2022-11-08 8:17 ` Peter B.
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