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How to do 2-pass VP9 encoding in PyAV? #2019
Description
I wanted to do 2-pass VP9 encoding, as described by ffmpeg doc in PyAV.
However I discovered that we did have pass1, pass2 flags to enable the mode, but I couldn't find a way to assign the twopass_stat buffer for the underlying libavencode call
Is this something we don't support yet? If yes I'd love to work on a PR to support it, but I don't see an obvious existing way for PyAV to access the fields of codec-specific contexts like VPxEncoderContext so I am not sure if this is even doable.
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chaserhkj commentedon Sep 20, 2025
Ok just did a few dig and find out the libavcodec's standard way of doing 2-pass is not
twopass_statsbuffer as I have referred to above butstats_inandstats_outon the genericAVCodecContextstruct.And we have #791 #277 that I missed before since I was searching for "two pass" keyword while they are using the term "multi-pass"
I think this is still relevant feature since as quoted in ffmpeg VP9 doc:
I will try to proceed and see if #791 works, then re-submit the PR on behalf of original author @inrustwetrust with any needed edits since their account seems to be dormant .