Niklas Haas:
> From: Niklas Haas <g...@haasn.dev>
>
> Buggy ICCv4 profiles are unfortunately used in the wild, and it's quite
> easy to work around them by just forcing the white point to the correct
> value. Display a warning just in case.
>
> See-Also: https://trac.ffmpeg.org/ticket/9673
> ---
> libavcodec/fflcms2.c | 45 ++++++++++++++++++++++++++++++++++++++++++++
> libavcodec/fflcms2.h | 7 +++++++
> 2 files changed, 52 insertions(+)
>
> diff --git a/libavcodec/fflcms2.c b/libavcodec/fflcms2.c
> index 5443f178bc9..41732c9c862 100644
> --- a/libavcodec/fflcms2.c
> +++ b/libavcodec/fflcms2.c
> @@ -201,6 +201,51 @@ static av_always_inline void XYZ_xy(cmsCIEXYZ XYZ,
> AVCIExy *xy)
> xy->y = av_d2q(k * XYZ.Y, 100000);
> }
>
> +static const AVCIExy wp_d50 = { {3457, 10000}, {3585, 10000} }; /* CIE D50 */
> +
> +int ff_icc_profile_sanitize(FFIccContext *s, cmsHPROFILE profile)
> +{
> + cmsCIEXYZ *white, fixed;
> + AVCIExy wpxy;
> + AVRational diff, z;
> + if (!profile)
> + return 0;
> +
> + if (cmsGetEncodedICCversion(profile) >= 0x4000000) { // ICC v4
> + switch (cmsGetHeaderRenderingIntent(profile)) {
> + case INTENT_RELATIVE_COLORIMETRIC:
> + case INTENT_ABSOLUTE_COLORIMETRIC: ;
> + /* ICC v4 colorimetric profiles are specified to always use D50
> + * media white point, anything else is a violation of the spec.
> + * Sadly, such profiles are incredibly common (Apple...), so make
> + * an effort to fix them. */
> + if (!(white = cmsReadTag(profile, cmsSigMediaWhitePointTag)))
> + return AVERROR_INVALIDDATA;
> + XYZ_xy(*white, &wpxy);
> + diff = av_add_q(av_abs_q(av_sub_q(wpxy.x, wp_d50.x)),
> + av_abs_q(av_sub_q(wpxy.y, wp_d50.y)));
> + if (av_cmp_q(diff, av_make_q(1, 1000)) > 0) {
> + av_log(s->avctx, AV_LOG_WARNING, "Invalid colorimetric ICCv4
> "
> + "profile media white point tag (expected %.4f %.4f, "
> + "got %.4f %.4f)\n",
> + av_q2d(wp_d50.x), av_q2d(wp_d50.y),
> + av_q2d(wpxy.x), av_q2d(wpxy.y));
Will this warn on every frame?
> + /* x+y+z = 1 */
> + z = av_sub_q(av_sub_q(av_make_q(1, 1), wp_d50.x), wp_d50.y);
> + fixed.X = av_q2d(av_div_q(wp_d50.x, wp_d50.y)) * white->Y;
> + fixed.Y = white->Y;
> + fixed.Z = av_q2d(av_div_q(z, wp_d50.y)) * white->Y;
> + if (!cmsWriteTag(profile, cmsSigMediaWhitePointTag, &fixed))
> + return AVERROR_EXTERNAL;
> + }
> + break;
> + default: break;
> + }
> + }
> +
> + return 0;
> +}
> +
> int ff_icc_profile_read_primaries(FFIccContext *s, cmsHPROFILE profile,
> AVColorPrimariesDesc *out_primaries)
> {
> diff --git a/libavcodec/fflcms2.h b/libavcodec/fflcms2.h
> index af63c9a13c8..b54173e50e2 100644
> --- a/libavcodec/fflcms2.h
> +++ b/libavcodec/fflcms2.h
> @@ -65,6 +65,13 @@ int ff_icc_profile_generate(FFIccContext *s,
> */
> int ff_icc_profile_attach(FFIccContext *s, cmsHPROFILE profile, AVFrame
> *frame);
>
> +/**
> + * Sanitize an ICC profile to try and fix badly broken values.
> + *
> + * Returns 0 on success, or a negative error code.
> + */
> +int ff_icc_profile_sanitize(FFIccContext *s, cmsHPROFILE profile);
Why is this a separate function and not just a new parameter to
ff_icc_profile_read_primaries() given that these seem to always be used
a pair?
- Andreas
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
To unsubscribe, visit link above, or email
ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
