Add support for Y'CbCr output split between multiple textures.

[movit] / effect_chain.h

diff --git a/effect_chain.h b/effect_chain.h
index 1be98916d9ccd6952580aef165488c55cecc7588..e07c2e9061b9b01f68d6baf753dacec03cead707 100644 (file)
--- a/effect_chain.h
+++ b/effect_chain.h
@@ -55,6 +55,34 @@ enum OutputAlphaFormat {
        OUTPUT_ALPHA_FORMAT_POSTMULTIPLIED,
 };
 
+// RGBA output is nearly always packed; Y'CbCr, however, is often planar
+// due to chroma subsampling. This enum controls how add_ycbcr_output()
+// distributes the color channels between the fragment shader outputs.
+// Obviously, anything except YCBCR_OUTPUT_INTERLEAVED will be meaningless
+// unless you use render_to_fbo() and have an FBO with multiple render
+// targets attached (the other outputs will be discarded).
+enum YCbCrOutputSplitting {
+       // Only one output: Store Y'CbCr into the first three output channels,
+       // respectively, plus alpha. This is also called “chunked” or
+       // ”packed” mode.
+       YCBCR_OUTPUT_INTERLEAVED,
+
+       // Store Y' and alpha into the first output (in the red and alpha
+       // channels; effect to the others is undefined), and Cb and Cr into
+       // the first two channels of the second output. This is particularly
+       // useful if you want to end up in a format like NV12, where all the
+       // Y' samples come first and then Cb and Cr come interlevaed afterwards.
+       // You will still need to do the chroma subsampling yourself to actually
+       // get down to NV12, though.
+       YCBCR_OUTPUT_SPLIT_Y_AND_CBCR,
+
+       // Store Y' and alpha into the first output, Cb into the first channel
+       // of the second output and Cr into the first channel of the third output.
+       // (Effect on the other channels is undefined.) Essentially gives you
+       // 4:4:4 planar, or ”yuv444p”.
+       YCBCR_OUTPUT_PLANAR,
+};
+
 // A node in the graph; basically an effect and some associated information.
 class Node {
 public:
@@ -186,7 +214,8 @@ public:
        // Currently, only chunked packed output is supported, and only 4:4:4
        // (so chroma_subsampling_x and chroma_subsampling_y must both be 1).
        void add_ycbcr_output(const ImageFormat &format, OutputAlphaFormat alpha_format,
-                             const YCbCrFormat &ycbcr_format);
+                             const YCbCrFormat &ycbcr_format,
+                             YCbCrOutputSplitting output_splitting = YCBCR_OUTPUT_INTERLEAVED);
 
        // Set number of output bits, to scale the dither.
        // 8 is the right value for most outputs.
@@ -338,7 +367,8 @@ private:
 
        enum OutputColorType { OUTPUT_COLOR_RGB, OUTPUT_COLOR_YCBCR };
        OutputColorType output_color_type;
-       YCbCrFormat output_ycbcr_format;  // If output_color_type == OUTPUT_COLOR_YCBCR.
+       YCbCrFormat output_ycbcr_format;              // If output_color_type == OUTPUT_COLOR_YCBCR.
+       YCbCrOutputSplitting output_ycbcr_splitting;  // If output_color_type == OUTPUT_COLOR_YCBCR.
 
        std::vector<Node *> nodes;
        std::map<Effect *, Node *> node_map;