lavfi: add vf_iccdetect for parsing ICC profiles

This filter is designed to parse embedded ICC profiles and attempt
extracting colorspace tags from them, updating the AVFrame metadata
accordingly.

This is intentionally made a separate filter, rather than being part of
libavcodec itself, so that it's an opt-in behavior for the time being.
This also gives the user more flexibility to e.g. first attach an ICC
profile and then also set the colorspace tags from it.

This makes #9673 possible, though not automatic.

Signed-off-by: Niklas Haas <git@haasn.dev>

configure

@@ -3665,6 +3665,7 @@ gblur_vulkan_filter_deps="vulkan spirv_compiler"
 hflip_vulkan_filter_deps="vulkan spirv_compiler"
 histeq_filter_deps="gpl"
 hqdn3d_filter_deps="gpl"
+iccdetect_filter_deps="lcms2"
 iccgen_filter_deps="lcms2"
 interlace_filter_deps="gpl"
 kerndeint_filter_deps="gpl"

doc/filters.texi

@@ -14384,6 +14384,20 @@ By default value is 0.
 
 The @code{hysteresis} filter also supports the @ref{framesync} options.
 
+@section iccdetect
+
+Detect the colorspace  from an embedded ICC profile (if present), and update
+the frame's tags accordingly.
+
+This filter accepts the following options:
+
+@table @option
+@item force
+If true, the frame's existing colorspace tags will always be overridden by
+values detected from an ICC profile. Otherwise, they will only be assigned if
+they contain @code{unknown}. Enabled by default.
+@end table
+
 @section iccgen
 
 Generate ICC profiles and attach them to frames.

libavfilter/Makefile

@@ -322,6 +322,7 @@ OBJS-$(CONFIG_HWMAP_FILTER)                  += vf_hwmap.o
 OBJS-$(CONFIG_HWUPLOAD_CUDA_FILTER)          += vf_hwupload_cuda.o
 OBJS-$(CONFIG_HWUPLOAD_FILTER)               += vf_hwupload.o
 OBJS-$(CONFIG_HYSTERESIS_FILTER)             += vf_hysteresis.o framesync.o
+OBJS-$(CONFIG_ICCDETECT_FILTER)              += vf_iccdetect.o fflcms2.o colorspace.o
 OBJS-$(CONFIG_ICCGEN_FILTER)                 += vf_iccgen.o fflcms2.o colorspace.o
 OBJS-$(CONFIG_IDENTITY_FILTER)               += vf_identity.o
 OBJS-$(CONFIG_IDET_FILTER)                   += vf_idet.o

libavfilter/allfilters.c

@@ -305,6 +305,7 @@ extern const AVFilter ff_vf_hwmap;
 extern const AVFilter ff_vf_hwupload;
 extern const AVFilter ff_vf_hwupload_cuda;
 extern const AVFilter ff_vf_hysteresis;
+extern const AVFilter ff_vf_iccdetect;
 extern const AVFilter ff_vf_iccgen;
 extern const AVFilter ff_vf_identity;
 extern const AVFilter ff_vf_idet;

libavfilter/vf_iccdetect.c

@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2022 Niklas Haas
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * filter for generating ICC profiles
+ */
+
+#include <lcms2.h>
+
+#include "libavutil/opt.h"
+#include "libavutil/pixdesc.h"
+
+#include "avfilter.h"
+#include "fflcms2.h"
+#include "internal.h"
+
+typedef struct IccDetectContext {
+    const AVClass *class;
+    FFIccContext icc;
+    int force;
+    /* (cached) detected ICC profile values */
+    AVBufferRef *profile;
+    enum AVColorPrimaries profile_prim;
+    enum AVColorTransferCharacteristic profile_trc;
+} IccDetectContext;
+
+#define OFFSET(x) offsetof(IccDetectContext, x)
+#define VF AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption iccdetect_options[] = {
+    { "force", "overwrite existing tags", OFFSET(force), AV_OPT_TYPE_BOOL, {.i64=1}, 0, 1, VF },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(iccdetect);
+
+static av_cold void iccdetect_uninit(AVFilterContext *avctx)
+{
+    IccDetectContext *s = avctx->priv;
+    av_buffer_unref(&s->profile);
+    ff_icc_context_uninit(&s->icc);
+}
+
+static av_cold int iccdetect_init(AVFilterContext *avctx)
+{
+    IccDetectContext *s = avctx->priv;
+    return ff_icc_context_init(&s->icc, avctx);
+}
+
+static int iccdetect_filter_frame(AVFilterLink *inlink, AVFrame *frame)
+{
+    AVFilterContext *avctx = inlink->dst;
+    IccDetectContext *s = avctx->priv;
+    const AVFrameSideData *sd;
+    struct ColorPrimaries coeffs;
+    cmsHPROFILE profile;
+    int ret;
+
+    sd = av_frame_get_side_data(frame, AV_FRAME_DATA_ICC_PROFILE);
+    if (!sd)
+        return ff_filter_frame(inlink->dst->outputs[0], frame);
+
+    if (s->profile && s->profile->data == sd->buf->data) {
+        /* No change from previous ICC profile */
+        goto done;
+    }
+
+    if ((ret = av_buffer_replace(&s->profile, sd->buf)) < 0)
+        return ret;
+    s->profile_prim = AVCOL_PRI_UNSPECIFIED;
+    s->profile_trc = AVCOL_TRC_UNSPECIFIED;
+
+    profile = cmsOpenProfileFromMemTHR(s->icc.ctx, sd->data, sd->size);
+    if (!profile)
+        return AVERROR_INVALIDDATA;
+
+    ret = ff_icc_profile_read_primaries(&s->icc, profile, &coeffs);
+    if (!ret)
+        ret = ff_icc_profile_detect_transfer(&s->icc, profile, &s->profile_trc);
+    cmsCloseProfile(profile);
+    if (ret < 0)
+        return ret;
+
+    s->profile_prim = ff_detect_color_primaries(&coeffs);
+
+done:
+    if (s->profile_prim != AVCOL_PRI_UNSPECIFIED) {
+        if (s->force || frame->color_primaries == AVCOL_PRI_UNSPECIFIED)
+            frame->color_primaries = s->profile_prim;
+    }
+
+    if (s->profile_trc != AVCOL_TRC_UNSPECIFIED) {
+        if (s->force || frame->color_trc == AVCOL_TRC_UNSPECIFIED)
+            frame->color_trc = s->profile_trc;
+    }
+
+    return ff_filter_frame(inlink->dst->outputs[0], frame);
+}
+
+static const AVFilterPad iccdetect_inputs[] = {
+    {
+        .name           = "default",
+        .type           = AVMEDIA_TYPE_VIDEO,
+        .filter_frame   = iccdetect_filter_frame,
+    },
+};
+
+static const AVFilterPad iccdetect_outputs[] = {
+    {
+        .name           = "default",
+        .type           = AVMEDIA_TYPE_VIDEO,
+    },
+};
+
+const AVFilter ff_vf_iccdetect = {
+    .name        = "iccdetect",
+    .description = NULL_IF_CONFIG_SMALL("Detect and parse ICC profiles."),
+    .priv_size   = sizeof(IccDetectContext),
+    .priv_class  = &iccdetect_class,
+    .flags       = AVFILTER_FLAG_METADATA_ONLY,
+    .init        = &iccdetect_init,
+    .uninit      = &iccdetect_uninit,
+    FILTER_INPUTS(iccdetect_inputs),
+    FILTER_OUTPUTS(iccdetect_outputs),
+};