Fix an issue where RGBA videos would flicker.

The issue would be that the preview chains and the live chain would often
have different sRGB texture needs, and they'd run at the same time and thus
have a race condition. Solve this by using a sampler object instead, which
overrides the texture state.

diff --git a/Makefile b/Makefile
index 9dc55261a97068601a560001d30be91f7a23bc2a..1a041fefab6d297e11f2fcbdd572e807424e01c4 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ OBJS += midi_mapper.o midi_mapping.pb.o
 
 # Mixer objects
 AUDIO_MIXER_OBJS = audio_mixer.o alsa_input.o alsa_pool.o ebu_r128_proc.o stereocompressor.o resampling_queue.o flags.o correlation_measurer.o filter.o input_mapping.o state.pb.o
-OBJS += chroma_subsampler.o v210_converter.o mixer.o pbo_frame_allocator.o context.o ref_counted_frame.o theme.o httpd.o flags.o image_input.o alsa_output.o disk_space_estimator.o print_latency.o timecode_renderer.o $(AUDIO_MIXER_OBJS)
+OBJS += chroma_subsampler.o v210_converter.o mixer.o pbo_frame_allocator.o context.o ref_counted_frame.o theme.o httpd.o flags.o image_input.o alsa_output.o disk_space_estimator.o print_latency.o timecode_renderer.o tweaked_inputs.o $(AUDIO_MIXER_OBJS)
 
 # Streaming and encoding objects
 OBJS += quicksync_encoder.o x264_encoder.o x264_dynamic.o x264_speed_control.o video_encoder.o metacube2.o mux.o audio_encoder.o ffmpeg_raii.o ffmpeg_util.o

diff --git a/mixer.cpp b/mixer.cpp
index 3a14a757431a88b2924a3430dcbf922fe1b3e73c..c21ac95943bcbbaa7a6b97e4def90bf6d70770ea 100644 (file)
--- a/mixer.cpp
+++ b/mixer.cpp
@@ -212,7 +212,9 @@ Mixer::Mixer(const QSurfaceFormat &format, unsigned num_cards)
        check_error();
 
        // This nearly always should be true.
-       global_flags.can_disable_srgb_decoder = epoxy_has_gl_extension("GL_EXT_texture_sRGB_decode");
+       global_flags.can_disable_srgb_decoder =
+               epoxy_has_gl_extension("GL_EXT_texture_sRGB_decode") &&
+               epoxy_has_gl_extension("GL_ARB_sampler_objects");
 
        // Since we allow non-bouncing 4:2:2 YCbCrInputs, effective subpixel precision
        // will be halved when sampling them, and we need to compensate here.

diff --git a/tweaked_inputs.cpp b/tweaked_inputs.cpp
new file mode 100644 (file)
index 0000000..304c3b4
--- /dev/null
+++ b/tweaked_inputs.cpp
@@ -0,0 +1,48 @@
+#include <epoxy/gl.h>
+#include <movit/flat_input.h>
+#include <movit/util.h>
+
+#include "tweaked_inputs.h"
+
+sRGBSwitchingFlatInput::~sRGBSwitchingFlatInput()
+{
+       if (sampler_obj != 0) {
+               glDeleteSamplers(1, &sampler_obj);
+       }
+}
+
+void sRGBSwitchingFlatInput::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
+{
+       movit::FlatInput::set_gl_state(glsl_program_num, prefix, sampler_num);
+       texture_unit = *sampler_num - 1;
+
+       if (sampler_obj == 0) {
+               glGenSamplers(1, &sampler_obj);
+               check_error();
+               glSamplerParameteri(sampler_obj, GL_TEXTURE_MIN_FILTER, needs_mipmaps ? GL_LINEAR_MIPMAP_NEAREST : GL_LINEAR);
+               check_error();
+               glSamplerParameteri(sampler_obj, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+               check_error();
+               glSamplerParameteri(sampler_obj, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+               check_error()
+               // This needs to be done on a sampler and not a texture parameter,
+               // because the texture could be used from multiple different
+               // contexts at the same time. This flag is ignored for non-sRGB-uploaded
+               // textures, so we can set it without checking can_output_linear_gamma().
+               if (output_linear_gamma) {
+                       glSamplerParameteri(sampler_obj, GL_TEXTURE_SRGB_DECODE_EXT, GL_DECODE_EXT);
+               } else {
+                       glSamplerParameteri(sampler_obj, GL_TEXTURE_SRGB_DECODE_EXT, GL_SKIP_DECODE_EXT);
+               }
+               check_error();
+       }
+
+       glBindSampler(texture_unit, sampler_obj);
+       check_error();
+}
+
+void sRGBSwitchingFlatInput::clear_gl_state()
+{
+       glBindSampler(texture_unit, 0);
+       check_error();
+}

diff --git a/tweaked_inputs.h b/tweaked_inputs.h
index 37c67827fe922f0cc247035729b50bec49e69deb..0ca13ced94877a3084fec7609bdc0cdd93a39f8b 100644 (file)
--- a/tweaked_inputs.h
+++ b/tweaked_inputs.h
@@ -47,30 +47,26 @@ public:
        sRGBSwitchingFlatInput(movit::ImageFormat format, movit::MovitPixelFormat pixel_format, GLenum type, unsigned width, unsigned height)
            : movit::FlatInput(format, pixel_format, type, width, height) {}
 
-       void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num) override
-       {
-               movit::FlatInput::set_gl_state(glsl_program_num, prefix, sampler_num);
-
-               // This flag is ignored for non-sRGB-uploaded textures, so we can set it
-               // without checking can_output_linear_gamma().
-               glActiveTexture(GL_TEXTURE0 + *sampler_num - 1);
-               if (output_linear_gamma) {
-                       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_SRGB_DECODE_EXT, GL_DECODE_EXT);
-               } else {
-                       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_SRGB_DECODE_EXT, GL_SKIP_DECODE_EXT);
-               }
-       }
+       ~sRGBSwitchingFlatInput();
+       void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num) override;
+       void clear_gl_state() override;
 
        bool set_int(const std::string &key, int value) override
        {
                if (key == "output_linear_gamma") {
                        output_linear_gamma = value;
                }
+               if (key == "needs_mipmaps") {
+                       needs_mipmaps = value;
+               }
                return movit::FlatInput::set_int(key, value);
        }
 
 private:
-       int output_linear_gamma = false;
+       bool output_linear_gamma = false;
+       bool needs_mipmaps = false;
+       GLuint sampler_obj = 0;
+       GLuint texture_unit;
 };