[FFmpeg-devel] [PATCH v8 1/2] avcodec/libjxldec: properly tag output colorspace

[Leo Izen <leo.izen@gmail.com>]

Whether an ICC profile is present or not, the decoder
should now properly tag the colorspace of pixel data
received by the decoder.
---
 libavcodec/libjxldec.c | 142 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 133 insertions(+), 9 deletions(-)

diff --git a/libavcodec/libjxldec.c b/libavcodec/libjxldec.c
index cd4bca3343..d2e0616124 100644
--- a/libavcodec/libjxldec.c
+++ b/libavcodec/libjxldec.c
@@ -27,6 +27,7 @@
 #include "libavutil/avassert.h"
 #include "libavutil/buffer.h"
 #include "libavutil/common.h"
+#include "libavutil/csp.h"
 #include "libavutil/error.h"
 #include "libavutil/mem.h"
 #include "libavutil/pixdesc.h"
@@ -92,7 +93,7 @@ static av_cold int libjxl_decode_init(AVCodecContext *avctx)
     return libjxl_init_jxl_decoder(avctx);
 }
 
-static enum AVPixelFormat libjxl_get_pix_fmt(AVCodecContext *avctx, JxlBasicInfo *basic_info, JxlPixelFormat *format)
+static enum AVPixelFormat libjxl_get_pix_fmt(void *avctx, const JxlBasicInfo *basic_info, JxlPixelFormat *format)
 {
     format->endianness = JXL_NATIVE_ENDIAN;
     format->num_channels = basic_info->num_color_channels + (basic_info->alpha_bits > 0);
@@ -129,12 +130,71 @@ static enum AVPixelFormat libjxl_get_pix_fmt(AVCodecContext *avctx, JxlBasicInfo
     return AV_PIX_FMT_NONE;
 }
 
+static enum AVColorPrimaries libjxl_get_primaries(void *avctx, const JxlColorEncoding *jxl_color)
+{
+    AVColorPrimariesDesc desc;
+    enum AVColorPrimaries prim;
+
+    /* libjxl populates these double values even if it uses an enum space */
+    desc.prim.r.x = av_d2q(jxl_color->primaries_red_xy[0], 300000);
+    desc.prim.r.y = av_d2q(jxl_color->primaries_red_xy[1], 300000);
+    desc.prim.g.x = av_d2q(jxl_color->primaries_green_xy[0], 300000);
+    desc.prim.g.y = av_d2q(jxl_color->primaries_green_xy[1], 300000);
+    desc.prim.b.x = av_d2q(jxl_color->primaries_blue_xy[0], 300000);
+    desc.prim.b.y = av_d2q(jxl_color->primaries_blue_xy[1], 300000);
+    desc.wp.x = av_d2q(jxl_color->white_point_xy[0], 300000);
+    desc.wp.y = av_d2q(jxl_color->white_point_xy[1], 300000);
+
+    prim = av_csp_primaries_id_from_desc(&desc);
+    if (prim == AVCOL_PRI_UNSPECIFIED) {
+        /* try D65 with the same primaries */
+        /* BT.709 uses D65 white point */
+        const AVWhitepointCoefficients *d65 = &av_csp_primaries_desc_from_id(AVCOL_PRI_BT709)->wp;
+        desc.wp = *d65;
+        av_log(avctx, AV_LOG_WARNING, "Changing unknown white point to D65\n");
+        prim = av_csp_primaries_id_from_desc(&desc);
+    }
+
+    return prim;
+}
+
+static enum AVColorTransferCharacteristic libjxl_get_trc(void *avctx, const JxlColorEncoding *jxl_color)
+{
+    switch (jxl_color->transfer_function) {
+    case JXL_TRANSFER_FUNCTION_709:
+        return AVCOL_TRC_BT709;
+    case JXL_TRANSFER_FUNCTION_LINEAR:
+        return AVCOL_TRC_LINEAR;
+    case JXL_TRANSFER_FUNCTION_SRGB:
+        return AVCOL_TRC_IEC61966_2_1;
+    case JXL_TRANSFER_FUNCTION_PQ:
+        return AVCOL_TRC_SMPTE2084;
+    case JXL_TRANSFER_FUNCTION_DCI:
+        return AVCOL_TRC_SMPTE428;
+    case JXL_TRANSFER_FUNCTION_HLG:
+        return AVCOL_TRC_ARIB_STD_B67;
+    case JXL_TRANSFER_FUNCTION_GAMMA:
+        if (jxl_color->gamma > 2.199 && jxl_color->gamma < 2.201)
+            return AVCOL_TRC_GAMMA22;
+        else if (jxl_color->gamma > 2.799 && jxl_color->gamma < 2.801)
+            return AVCOL_TRC_GAMMA28;
+        else
+            av_log(avctx, AV_LOG_WARNING, "Unsupported gamma transfer: %f\n", jxl_color->gamma);
+        break;
+    default:
+        av_log(avctx, AV_LOG_WARNING, "Unknown transfer function: %d\n", jxl_color->transfer_function);
+    }
+
+    return AVCOL_TRC_UNSPECIFIED;
+}
+
 static int libjxl_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *avpkt)
 {
     LibJxlDecodeContext *ctx = avctx->priv_data;
     uint8_t *buf = avpkt->data;
     size_t remaining = avpkt->size, iccp_len;
     JxlDecoderStatus jret;
+    JxlColorEncoding jxl_color;
     int ret;
     *got_frame = 0;
 
@@ -189,16 +249,80 @@ static int libjxl_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_f
             continue;
         case JXL_DEC_COLOR_ENCODING:
             av_log(avctx, AV_LOG_DEBUG, "COLOR_ENCODING event emitted\n");
-            jret = JxlDecoderGetICCProfileSize(ctx->decoder, &ctx->jxl_pixfmt, JXL_COLOR_PROFILE_TARGET_ORIGINAL, &iccp_len);
-            if (jret == JXL_DEC_SUCCESS && iccp_len > 0) {
-                av_buffer_unref(&ctx->iccp);
-                ctx->iccp = av_buffer_alloc(iccp_len);
-                if (!ctx->iccp)
-                    return AVERROR(ENOMEM);
-                jret = JxlDecoderGetColorAsICCProfile(ctx->decoder, &ctx->jxl_pixfmt, JXL_COLOR_PROFILE_TARGET_ORIGINAL, ctx->iccp->data, iccp_len);
+            jret = JxlDecoderGetColorAsEncodedProfile(ctx->decoder, NULL, JXL_COLOR_PROFILE_TARGET_ORIGINAL, &jxl_color);
+            if (jret == JXL_DEC_SUCCESS) {
+                /* enum values describe the colors of this image */
+                jret = JxlDecoderSetPreferredColorProfile(ctx->decoder, &jxl_color);
+                if (jret == JXL_DEC_SUCCESS)
+                    jret = JxlDecoderGetColorAsEncodedProfile(ctx->decoder, &ctx->jxl_pixfmt, JXL_COLOR_PROFILE_TARGET_DATA, &jxl_color);
+            } else {
+                /* an ICC Profile is present in the stream */
+                if (ctx->basic_info.uses_original_profile) {
+                    av_log(avctx, AV_LOG_VERBOSE, "Using embedded ICC Profile\n");
+                    /* an ICC profile is present, and we can meaningfully get it,
+                     * because the pixel data is not XYB-encoded */
+                    jret = JxlDecoderGetICCProfileSize(ctx->decoder, &ctx->jxl_pixfmt, JXL_COLOR_PROFILE_TARGET_DATA, &iccp_len);
+                    if (jret == JXL_DEC_SUCCESS && iccp_len > 0) {
+                        av_buffer_unref(&ctx->iccp);
+                        ctx->iccp = av_buffer_alloc(iccp_len);
+                        if (!ctx->iccp)
+                            return AVERROR(ENOMEM);
+                        jret = JxlDecoderGetColorAsICCProfile(ctx->decoder, &ctx->jxl_pixfmt, JXL_COLOR_PROFILE_TARGET_DATA, ctx->iccp->data, iccp_len);
+                        if (jret != JXL_DEC_SUCCESS) {
+                            av_log(avctx, AV_LOG_WARNING, "Unable to obtain ICCP from header\n");
+                            av_buffer_unref(&ctx->iccp);
+                        }
+                    }
+                }
+                /* when libjxl adds JxlDecoderSetICCProfile() properly handle the XYB case as well */
+            }
+
+            avctx->color_range = frame->color_range = AVCOL_RANGE_JPEG;
+            if (ctx->jxl_pixfmt.num_channels >= 3)
+                avctx->colorspace = AVCOL_SPC_RGB;
+            avctx->color_primaries = AVCOL_PRI_UNSPECIFIED;
+            avctx->color_trc = AVCOL_TRC_UNSPECIFIED;
+
+            if (!ctx->iccp) {
+                /* checking enum values */
+                if (jret == JXL_DEC_SUCCESS) {
+                    if (avctx->colorspace == AVCOL_SPC_RGB)
+                        avctx->color_primaries = libjxl_get_primaries(avctx, &jxl_color);
+                    avctx->color_trc = libjxl_get_trc(avctx, &jxl_color);
+                }
+                /* fall back on wide gamut if enum values fail */
+                if (avctx->color_primaries == AVCOL_PRI_UNSPECIFIED) {
+                    if (avctx->colorspace == AVCOL_SPC_RGB) {
+                        av_log(avctx, AV_LOG_WARNING, "Falling back on wide gamut output\n");
+                        jxl_color.primaries = JXL_PRIMARIES_2100;
+                        avctx->color_primaries = AVCOL_PRI_BT2020;
+                    }
+                    /* libjxl requires this set even for grayscale */
+                    jxl_color.white_point = JXL_WHITE_POINT_D65;
+                }
+                if (avctx->color_trc == AVCOL_TRC_UNSPECIFIED) {
+                    if (ctx->jxl_pixfmt.data_type == JXL_TYPE_FLOAT
+                        || ctx->jxl_pixfmt.data_type == JXL_TYPE_FLOAT16) {
+                        av_log(avctx, AV_LOG_WARNING, "Falling back on Linear Light transfer\n");
+                        jxl_color.transfer_function = JXL_TRANSFER_FUNCTION_LINEAR;
+                        avctx->color_trc = AVCOL_TRC_LINEAR;
+                    } else {
+                        av_log(avctx, AV_LOG_WARNING, "Falling back on iec61966-2-1/sRGB transfer\n");
+                        jxl_color.transfer_function = JXL_TRANSFER_FUNCTION_SRGB;
+                        avctx->color_trc = AVCOL_TRC_IEC61966_2_1;
+                    }
+                }
+                /* all colors will be in-gamut so we want accurate colors */
+                jxl_color.rendering_intent = JXL_RENDERING_INTENT_RELATIVE;
+                jxl_color.color_space = avctx->colorspace == AVCOL_SPC_RGB ? JXL_COLOR_SPACE_RGB : JXL_COLOR_SPACE_GRAY;
+                jret = JxlDecoderSetPreferredColorProfile(ctx->decoder, &jxl_color);
                 if (jret != JXL_DEC_SUCCESS)
-                    av_buffer_unref(&ctx->iccp);
+                    av_log(avctx, AV_LOG_WARNING, "Unable to set fallback color encoding\n");
             }
+
+            frame->color_trc = avctx->color_trc;
+            frame->color_primaries = avctx->color_primaries;
+            frame->colorspace = avctx->colorspace;
             continue;
         case JXL_DEC_NEED_IMAGE_OUT_BUFFER:
             av_log(avctx, AV_LOG_DEBUG, "NEED_IMAGE_OUT_BUFFER event emitted\n");
-- 
2.36.1

_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".