[Cellar] Re: [PATCH] ffv1: Support CRC with initial -1 and final -1 values

[Michael Niedermayer <[e-mail]>]

On Wed, Sep 25, 2024 at 10:06:16AM +0200, Michael Niedermayer wrote:
> This allows detection of appended and prepended 0 bits.
> Previously a correct block could have 0 bits added before and
> after it and this would not be detected with the CRC.
> 
> I am not aware of such a case actually occurring in the real world but this
> should improve the performance of the checksum slightly
> 
> Signed-off-by: Michael Niedermayer <[e-mail]>
> ---
>  ffv1.md | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/ffv1.md b/ffv1.md
> index bb5361d..5c1e290 100644
> --- a/ffv1.md
> +++ b/ffv1.md
> @@ -1267,7 +1267,8 @@ Figure: Description of the coding of `initial_state_delta[ i ][ j ][ k ]`. {#fig
>  |value | error detection/correction type           |
>  |------|:------------------------------------------|
>  |0     | 32-bit CRC in `ConfigurationRecord`       |
> -|1     | 32-bit CRC in `Slice` and `ConfigurationRecord`|
> +|1     | 32-bit CRC in `Slice` and `ConfigurationRecord` using crcref=0  as initial and final values|
> +|2     | 32-bit CRC in `Slice` and `ConfigurationRecord` using crcref=-1 as initial and final values|
>  |Other | reserved for future use                   |
>  Table: The definitions for `ec` values. {#tableEc}

Does someone want an option like a SHA-256 or something "stronger" than a CRC ?
or some kind of error correction code, but iam not sure this is the right place for
that

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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