renderer: convert footage frames to reference pixel format

Due to an oversight, incoming footage frames were NOT converted to the
working pixel format (usually half or float). For most frames, this meant the
OCIO conversion would occur on frames while they were still in their source
format (usually either RGB8 or RGB16). This leads to rounding error
inaccuracies, but even worse GLSL will clamp integer textures to 1.0 potentially
losing a lot of data.

While later nodes would correctly convert to the appropriate format, by then it
would be too late. This commit corrects this issue, converting the frames to
float during the OCIO shader pass.

app/render/backend/opengl/openglproxy.cpp

@@ -115,7 +115,7 @@ void OpenGLProxy::FrameToValue(DecoderPtr decoder, StreamPtr stream, const TimeR
       }
     }
 
-    VideoRenderingParams footage_params(frame->width(), frame->height(), stream->timebase(), frame->format(), video_params_.mode());
+    VideoRenderingParams footage_params(frame->width(), frame->height(), frame->format());
 
     footage_tex_ref = texture_cache_.Get(ctx_, footage_params, frame->data());
 
@@ -140,13 +140,15 @@ void OpenGLProxy::FrameToValue(DecoderPtr decoder, StreamPtr stream, const TimeR
 
         footage_params = VideoRenderingParams(new_width,
                                               new_height,
-                                              footage_params.time_base(),
-                                              footage_params.format(),
-                                              footage_params.mode());
+                                              footage_params.format());
       }
 
+      VideoRenderingParams dest_params(footage_params.width(),
+                                       footage_params.height(),
+                                       video_params_.format());
+
       // Create destination texture
-      OpenGLTextureCache::ReferencePtr associated_tex_ref = texture_cache_.Get(ctx_, footage_params);
+      OpenGLTextureCache::ReferencePtr associated_tex_ref = texture_cache_.Get(ctx_, dest_params);
 
       buffer_.Attach(associated_tex_ref->texture(), true);
       buffer_.Bind();