no output file with cli

[AlexanderKozhevin]

!bvw embed -a seq -wm 2012 -i test.mp4 -o smalltest_output.mp4 -k 123 456 789 -j 8

OpenCV: FFMPEG: tag 0x34363268/'h264' is not supported with codec id 27 and format 'mp4 / MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x31637661/'avc1'
[ERROR:[email protected]] global cap_ffmpeg_impl.hpp:3133 open Could not find encoder for codec_id=27, error: Encoder not found
[ERROR:[email protected]] global cap_ffmpeg_impl.hpp:3211 open VIDEOIO/FFMPEG: Failed to initialize VideoWriter
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[Quakumei]

OpenCV: FFMPEG: tag 0x34363268/'h264' is not supported with codec id 27 and format 'mp4 / MP4 (MPEG-4 Part 14)'
OpenCV: FFMPEG: fallback to use tag 0x31637661/'avc1'
[ERROR:[email protected]] global cap_ffmpeg_impl.hpp:3133 open Could not find encoder for codec_id=27, error: Encoder not found
[ERROR:[email protected]] global cap_ffmpeg_impl.hpp:3211 open VIDEOIO/FFMPEG: Failed to initialize VideoWriter

h264 is unavailable in simple pip install opencv-python. You need to build the package yourself with mp4 support.

This helped me:

sudo apt install build-essential cmake git python3-dev python3-numpy \
libavcodec-dev libavformat-dev libswscale-dev \
libgstreamer-plugins-base1.0-dev \
libgstreamer1.0-dev libgtk-3-dev \
libpng-dev libjpeg-dev libopenexr-dev libtiff-dev libwebp-dev \
libopencv-dev x264 libx264-dev libssl-dev ffmpeg

python -m pip install --no-binary opencv-python opencv-python

source:
opencv/opencv-python#207
https://stackoverflow.com/questions/70247344/save-video-in-opencv-with-h264-codec
opencv/opencv-python#299