fixing dt time calculation (#11)

* fix dt time calculation

* adding dt_test.cine

* Add test for frame timestamps

* Filter out dt_test from bulk test list

* Fix loading/filtering order for test files

* convert fracstart and TriggerTime.fractions to Float64 before subtraction

---------

Co-authored-by: Alex Ames <alexander.m.ames@gmail.com>

src/CineFiles.jl

@@ -428,7 +428,7 @@ function CineHeader(fname)
             secstart = read(f, UInt32)
             dt[i] =
                 (secstart - cine.TriggerTime.seconds) +
-                ((fracstart - cine.TriggerTime.fractions) / 2^32)
+                ((fracstart / 2^32  - cine.TriggerTime.fractions / 2^32 ))
         end
 
         # Packing options

test/runtests.jl

@@ -38,7 +38,10 @@ function compare_images(cine_file, tiff_image, frame_no=1)
     return all(isapprox.(cine_frame_gamma, tiff_image; atol=0.01))
 end
 
-cine_file_paths = cine_test_files.(glob("*.cine", "data"))
+cine_base_paths = glob("*.cine", "data")
+# Don't perform xml/tif cross-verification on dt_test cine file
+filter!(f -> !occursin("dt_test", f), cine_base_paths)
+cine_file_paths = cine_test_files.(cine_base_paths)
 append!(cine_file_paths, cine_test_files.(glob("*.cine", "proprietary_data")))
 
 @testset "CineFiles.jl" begin
@@ -88,6 +91,12 @@ append!(cine_file_paths, cine_test_files.(glob("*.cine", "proprietary_data")))
                   parse(Int, xml_data["CameraSetup"]["CameraVersion"])
         end
     end
+
+    @testset "Correct calculation of frame timestamps" begin
+        cf = CineFile(joinpath("data", "dt_test.cine"))
+        Δt = diff(cf.header.dt)
+        @test all(dt -> isapprox(dt, Δt[1], rtol=5e-8), Δt)
+    end
 end
 
 Aqua.test_all(CineFiles)