On Wed, Sep 27, 2023 at 03:56:15PM +0200, Niklas Haas wrote:
> From: Niklas Haas <g...@haasn.dev>
>
> The spec specifies x^31 + x^3 + 1 as the polynomial, but the diagram in
> Figure 1-1 omits the +1 offset. The initial implementation was based on
> the diagram, but this is wrong (produces subtly incorrect results).
> ---
> libavcodec/h274.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavcodec/h274.c b/libavcodec/h274.c
> index a69f9411429..fc111cdb50d 100644
> --- a/libavcodec/h274.c
> +++ b/libavcodec/h274.c
> @@ -38,7 +38,7 @@ static void prng_shift(uint32_t *state)
> {
> // Primitive polynomial x^31 + x^3 + 1 (modulo 2)
> uint32_t x = *state;
> - uint8_t feedback = (x >> 2) ^ (x >> 30);
> + uint8_t feedback = 1u ^ (x >> 2) ^ (x >> 30);
> *state = (x << 1) | (feedback & 1u);where can i find the text describing this that you refer to ? thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Rewriting code that is poorly written but fully understood is good. Rewriting code that one doesnt understand is a sign that one is less smart than the original author, trying to rewrite it will not make it better.
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