Add iterator interface to VideoReader objects #261
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I have added an iterator interface to the `VideoReader` type, making collecting all frames of a video as simple as `f = openvideo(fname); imgs = collect(f)`. The iterator returns a new array for each frame, as I think mutating the same array on subsequent calls to `iterate` would be surprising and lead to strange behavior when calling functions such as `collect`. Note that the VideoReader iterator is mutable, like Channel or Stateful iterators in Julia, and will resume iteration where it was last stopped, instead of at the beginning. I have added some text in the documentation explaining this behavior, and also added some tests.
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I'm confused by these testing errors. |
test/avio.jl
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| @test length(collect(v)) == VideoIO.TestVideos.videofiles[name].numframes | ||
| @test length(collect(v)) == 0 |
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| @test length(collect(v)) == VideoIO.TestVideos.videofiles[name].numframes | |
| @test length(collect(v)) == 0 | |
| imgstack = collect(v) | |
| @test length(imgstack) == VideoIO.TestVideos.videofiles[name].numframes | |
| imgstack = nothing | |
| @test length(collect(v)) == 0 | |
| GC.gc() |
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Yeah good points... if CI is memory limited I probably should not be using collect at all. I'll do some other test of the iterator interface that doesn't require storing all of the frames in memory at the same time.
Instead of collecting all frames into memory with `collect` to test the `VideoReader` interface, I am instead testing the iterator interface with a simple for loop. This should reduce the memory requirement for CI, and avoid memory-related test errors on low memory CI VMs.
Instead of looping over the iterator to test that there are zero elements remaining, it is simpler to just see if `iterate` returns `nothing`.
I have added a test to verify that frames returned by the `VideoReader` iterator interface have distinct storage.
Codecov Report
@@ Coverage Diff @@
## master #261 +/- ##
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- Coverage 77.13% 73.94% -3.20%
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Files 14 14
Lines 608 614 +6
==========================================
- Hits 469 454 -15
- Misses 139 160 +21
Continue to review full report at Codecov.
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Looks good now. Shall we merge? |
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Fine by me! |
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I have added an iterator interface to the
VideoReadertype, making collecting all frames of a video as simple as:The iterator returns a new array for each frame, as I think mutating the same array on subsequent calls to
iteratewould be surprising and lead to strange behavior when calling functions such ascollect. Note that the VideoReader iterator is mutable, like Channel or Stateful iterators in Julia, and will resume iteration where it was last stopped, instead of at the beginning. I have added some text in the documentation explaining this behavior, and also added some tests.