Fix a bunch of colorspace issues, after practical testing. There is still some left...

[nageru] / theme.cpp

diff --git a/theme.cpp b/theme.cpp
index 767abac0389f98ea318513c583bd11c8f24f3067..56d5f84553c5d00bcbb0406c6548ec703fecd059 100644 (file)
--- a/theme.cpp
+++ b/theme.cpp
@@ -123,15 +123,21 @@ int EffectChain_finalize(lua_State* L)
        bool is_main_chain = checkbool(L, 2);
 
        // Add outputs as needed.
+       // NOTE: If you change any details about the output format, you will need to
+       // also update what's given to the muxer (HTTPD::Mux constructor) and
+       // what's put in the H.264 stream (sps_rbsp()).
        ImageFormat inout_format;
-       inout_format.color_space = COLORSPACE_sRGB;
-       inout_format.gamma_curve = GAMMA_sRGB;
+       inout_format.color_space = COLORSPACE_REC_709;
+       inout_format.gamma_curve = GAMMA_REC_709;
        if (is_main_chain) {
                YCbCrFormat output_ycbcr_format;
+               // We actually output 4:2:0 in the end, but chroma subsampling
+               // happens in a pass not run by Movit (see Mixer::subsample_chroma()).
                output_ycbcr_format.chroma_subsampling_x = 1;
                output_ycbcr_format.chroma_subsampling_y = 1;
                output_ycbcr_format.luma_coefficients = YCBCR_REC_709;
                output_ycbcr_format.full_range = false;
+               output_ycbcr_format.num_levels = 256;
 
                chain->add_ycbcr_output(inout_format, OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED, output_ycbcr_format, YCBCR_OUTPUT_SPLIT_Y_AND_CBCR);
                chain->set_dither_bits(8);
@@ -319,6 +325,11 @@ LiveInputWrapper::LiveInputWrapper(Theme *theme, EffectChain *chain, bool overri
        inout_format.color_space = COLORSPACE_sRGB;
        inout_format.gamma_curve = GAMMA_sRGB;
 
+       // The Blackmagic driver docs claim that the device outputs Y'CbCr
+       // according to Rec. 601, but practical testing indicates it definitely
+       // is Rec. 709 (at least up to errors attributable to rounding errors).
+       // Perhaps 601 was only to indicate the subsampling positions, not the
+       // colorspace itself? Tested with a Lenovo X1 gen 3 as input.
        YCbCrFormat input_ycbcr_format;
        input_ycbcr_format.chroma_subsampling_x = 2;
        input_ycbcr_format.chroma_subsampling_y = 1;
@@ -326,7 +337,7 @@ LiveInputWrapper::LiveInputWrapper(Theme *theme, EffectChain *chain, bool overri
        input_ycbcr_format.cr_x_position = 0.0;
        input_ycbcr_format.cb_y_position = 0.5;
        input_ycbcr_format.cr_y_position = 0.5;
-       input_ycbcr_format.luma_coefficients = YCBCR_REC_601;
+       input_ycbcr_format.luma_coefficients = YCBCR_REC_709;
        input_ycbcr_format.full_range = false;
 
        if (override_bounce) {