Support JPEGs that are not 4:2:2.

diff --git a/jpeg_frame_view.cpp b/jpeg_frame_view.cpp
index 65fccbb0102e6877fa121ed7f9df240838c53a3d..0b481906be3cb00757264881b9f31ee7073fe75c 100644 (file)
--- a/jpeg_frame_view.cpp
+++ b/jpeg_frame_view.cpp
@@ -61,46 +61,58 @@ shared_ptr<Frame> decode_jpeg(const string &filename)
 
        jpeg_read_header(&dinfo, true);
 
-       if (dinfo.num_components != 3 ||
-            dinfo.comp_info[0].h_samp_factor != 2 ||
-            dinfo.comp_info[0].v_samp_factor != 2 ||
-            dinfo.comp_info[1].h_samp_factor != 1 ||
-            dinfo.comp_info[1].v_samp_factor != 2 ||
-            dinfo.comp_info[2].h_samp_factor != 1 ||
-            dinfo.comp_info[2].v_samp_factor != 2) {
-               fprintf(stderr, "Not 4:2:2 JPEG! (%d components, Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
+       if (dinfo.num_components != 3) {
+               fprintf(stderr, "Not a color JPEG. (%d components, Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
                        dinfo.num_components,
                        dinfo.comp_info[0].h_samp_factor, dinfo.comp_info[0].v_samp_factor,
                        dinfo.comp_info[1].h_samp_factor, dinfo.comp_info[1].v_samp_factor,
                        dinfo.comp_info[2].h_samp_factor, dinfo.comp_info[2].v_samp_factor);
                exit(1);
        }
+       if (dinfo.comp_info[0].h_samp_factor != dinfo.max_h_samp_factor ||
+           dinfo.comp_info[0].v_samp_factor != dinfo.max_v_samp_factor ||  // Y' must not be subsampled.
+           dinfo.comp_info[1].h_samp_factor != dinfo.comp_info[2].h_samp_factor ||
+           dinfo.comp_info[1].v_samp_factor != dinfo.comp_info[2].v_samp_factor ||  // Cb and Cr must be identically subsampled.
+           (dinfo.max_h_samp_factor % dinfo.comp_info[1].h_samp_factor) != 0 ||
+           (dinfo.max_v_samp_factor % dinfo.comp_info[1].v_samp_factor) != 0) {  // No 2:3 subsampling or other weirdness.
+               fprintf(stderr, "Unsupported subsampling scheme. (Y=%dx%d, Cb=%dx%d, Cr=%dx%d)\n",
+                       dinfo.comp_info[0].h_samp_factor, dinfo.comp_info[0].v_samp_factor,
+                       dinfo.comp_info[1].h_samp_factor, dinfo.comp_info[1].v_samp_factor,
+                       dinfo.comp_info[2].h_samp_factor, dinfo.comp_info[2].v_samp_factor);
+               exit(1);
+       }
        dinfo.raw_data_out = true;
 
        jpeg_start_decompress(&dinfo);
 
        frame->width = dinfo.output_width;
        frame->height = dinfo.output_height;
+       frame->chroma_subsampling_x = dinfo.max_h_samp_factor / dinfo.comp_info[1].h_samp_factor;
+       frame->chroma_subsampling_y = dinfo.max_v_samp_factor / dinfo.comp_info[1].v_samp_factor;
 
-       unsigned chroma_width_blocks = (dinfo.output_width + 15) / 16;
-       unsigned width_blocks = chroma_width_blocks * 2;
-       unsigned height_blocks = (dinfo.output_height + 15) / 16;
+       unsigned h_mcu_size = DCTSIZE * dinfo.max_h_samp_factor;
+       unsigned v_mcu_size = DCTSIZE * dinfo.max_v_samp_factor;
+       unsigned chroma_width_blocks = (dinfo.output_width + h_mcu_size - 1) / h_mcu_size;
+       unsigned width_blocks = chroma_width_blocks * dinfo.max_h_samp_factor;
+       unsigned chroma_height_blocks = (dinfo.output_height + v_mcu_size - 1) / v_mcu_size;
+       unsigned height_blocks = chroma_height_blocks * dinfo.max_v_samp_factor;
 
        // TODO: Decode into a PBO.
-       frame->y.reset(new uint8_t[width_blocks * (height_blocks * 2) * DCTSIZE2]);
-       frame->cb.reset(new uint8_t[chroma_width_blocks * (height_blocks * 2) * DCTSIZE2]);
-       frame->cr.reset(new uint8_t[chroma_width_blocks * (height_blocks * 2) * DCTSIZE2]);
+       frame->y.reset(new uint8_t[width_blocks * height_blocks * DCTSIZE2]);
+       frame->cb.reset(new uint8_t[chroma_width_blocks * chroma_height_blocks * DCTSIZE2]);
+       frame->cr.reset(new uint8_t[chroma_width_blocks * chroma_height_blocks * DCTSIZE2]);
 
-       JSAMPROW yptr[16], cbptr[16], crptr[16];
+       JSAMPROW yptr[v_mcu_size], cbptr[v_mcu_size], crptr[v_mcu_size];
        JSAMPARRAY data[3] = { yptr, cbptr, crptr };
-       for (unsigned y = 0; y < height_blocks; ++y) {
-               for (unsigned yy = 0; yy < DCTSIZE * 2; ++yy) {
-                       yptr[yy] = frame->y.get() + (y * DCTSIZE * 2 + yy) * width_blocks * DCTSIZE;
-                       cbptr[yy] = frame->cb.get() + (y * DCTSIZE * 2 + yy) * chroma_width_blocks * DCTSIZE;
-                       crptr[yy] = frame->cr.get() + (y * DCTSIZE * 2 + yy) * chroma_width_blocks * DCTSIZE;
+       for (unsigned y = 0; y < chroma_height_blocks; ++y) {
+               // NOTE: The last elements of cbptr/crptr will be unused for vertically subsampled chroma.
+               for (unsigned yy = 0; yy < v_mcu_size; ++yy) {
+                       yptr[yy] = frame->y.get() + (y * DCTSIZE * dinfo.max_v_samp_factor + yy) * width_blocks * DCTSIZE;
+                       cbptr[yy] = frame->cb.get() + (y * DCTSIZE * dinfo.comp_info[1].v_samp_factor + yy) * chroma_width_blocks * DCTSIZE;
+                       crptr[yy] = frame->cr.get() + (y * DCTSIZE * dinfo.comp_info[1].v_samp_factor + yy) * chroma_width_blocks * DCTSIZE;
                }
 
-               jpeg_read_raw_data(&dinfo, data, /*num_lines=*/16);
+               jpeg_read_raw_data(&dinfo, data, v_mcu_size);
        }
 
        (void) jpeg_finish_decompress(&dinfo);
@@ -221,7 +233,6 @@ void JPEGFrameView::initializeGL()
        ImageFormat image_format;
        image_format.color_space = COLORSPACE_sRGB;
        image_format.gamma_curve = GAMMA_sRGB;
-       YCbCrFormat ycbcr_format;
        ycbcr_format.luma_coefficients = YCBCR_REC_709;
        ycbcr_format.full_range = false;
        ycbcr_format.num_levels = 256;
@@ -275,6 +286,9 @@ void JPEGFrameView::setDecodedFrame(std::shared_ptr<Frame> frame)
                ycbcr_input->set_pitch(0, width_blocks * 16);
                ycbcr_input->set_pitch(1, width_blocks * 8);
                ycbcr_input->set_pitch(2, width_blocks * 8);
+               ycbcr_format.chroma_subsampling_x = frame->chroma_subsampling_x;
+               ycbcr_format.chroma_subsampling_y = frame->chroma_subsampling_y;
+               ycbcr_input->change_ycbcr_format(ycbcr_format);
                update();
        });
 }

diff --git a/jpeg_frame_view.h b/jpeg_frame_view.h
index 43418192bfa1969b6f731ea579183c8696b34dbf..478c4a672388fbb8c0673d1cba791b7fd10a3e31 100644 (file)
--- a/jpeg_frame_view.h
+++ b/jpeg_frame_view.h
@@ -14,6 +14,7 @@
 struct Frame {
        std::unique_ptr<uint8_t[]> y, cb, cr;
        unsigned width, height;
+       unsigned chroma_subsampling_x, chroma_subsampling_y;
 };
 
 class JPEGFrameView : public QGLWidget {
@@ -45,6 +46,7 @@ private:
        std::unique_ptr<movit::EffectChain> chain;
        std::shared_ptr<Frame> current_frame;  // So that we hold on to the pixels.
        movit::YCbCrInput *ycbcr_input;
+       movit::YCbCrFormat ycbcr_format;
 };
 
 #endif  // !defined(_JPEG_FRAME_VIEW_H)