Greetings. I do image signal processing as a hobby, especially playing around with images taken from video. I used to take screenshots using MPV, but I started to wonder if it would not be better to take shots from within Julia using VideoIO.jl. I have no real experience using video processing tool…

That argument controls the decoded pixel format, that is the pixel format in the arrays returned from the call. I suspect the problem here is the input pixel format stored in the video file, which should be handled automatically but isn’t for some reason. Can you share the video file?

I think we can find the format from the output from ffmpeg, since VideoIO is also using it: ffmpeg -i test.mkv ffmpeg version 5.0.1 Copyright (c) 2000-2022 the FFmpeg developers built with Apple clang version 13.1.6 (clang-1316.0.21.2.5) configuration: --prefix=/usr/local/Cellar/ffmpeg/5.0.1_3 …

I believe that is the list of supported output pixel formats, this should build an ffmpeg pipeline to transcode the pixel format to one of those (selected here ). Looking at the stack trace, this line stands out: avio.jl:275 bad_px_type = transcode && target_format !== nothing && !is_pixel_typ…

Thank you very much for your help so far. I did try running it now and this is the output in the session: ERROR: Unknown pixel format Stacktrace: [1] error(s::String) @ Base ./error.jl:33 [2] VideoIO.VideoReader(avin::VideoIO.AVInput{String}, video_stream::Int64; transcode::Bool, target_forma…

Huh, I expected more debug output. I’m not sure what to try next, I think that error is coming from FFMPEG. Hopefully someone more knowledgeable will chime in! As a workaround, you could try specifying a different pixel format during recording.

Thank you for trying to help. Looking at avframe_transfer.jl , they define 4 different functions to read frames based on the 4 specified formats, so I think this might be the issue here.

Here is a good one! My installed ffmpeg and the one used by VideoIO seem to have very different opinions about some files I created to test this. What does this command report for you: julia> import Pkg; Pkg.add("FFMPEG_jll") julia> using FFMPEG_jll julia> run(`$(FFMPEG_jll.ffprobe()) test.mkv`);…

Thank you for still trying to help. This is the output: ffprobe version 4.4 Copyright (c) 2007-2021 the FFmpeg developers built with clang version 11.0.1 (/home/ec2-user/.julia/dev/BinaryBuilderBase/deps/downloads/llvm-project.git 43ff75f2c3feef64f9d73328230d34dac8832a91) configuration: --enab…

Hurray, that is the same behavior I see! I think the problem is that FFMPEG_jll is built without --enable-libaom. The version I get in Ubuntu and the version you are using from Homebrew both the include that library for av1 decoding. I’m not sure why it was left out, but at least that is something c…

It would be good to open this as an issue on VideoIO. I think it’s clear that there’s a gap in support

VideoIO.jl can’t seem to open a .mkv video

General Usage

contradict July 11, 2022, 11:55pm 13

A new version of FFMPEG_jll (4.4.2) has been released with AV1 support. Updating your packages should get the new version, the commands here now succeed on my test video.

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VideoIO.jl can’t seem to open a .mkv video

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