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Clarification on H264 support of included ffmpeg #682
Description
The repo README states that the wheels of opencv-python include an ffmpeg licensed under LGPL. This implies that the included ffmpeg will not be able to read H264 videos, since this would require ffmpeg to be distributed under GPL (x264).
However, after installing opencv-python-headless version 4.3.0.38 from pip into a fresh python 3.8 environment, I am able to read video frames from an H264 encoded video:
>>> import cv2
>>> cap = cv2.VideoCapture("video.mp4") # H264 encoded video
>>> cap.isOpened()
True
>>> cap.getBackendName()
'FFMPEG'
>>> cap.read()
(True, array([[[33, 33, 33],
[33, 33, 33],
[33, 33, 33],
...
Verified this works on Mac and Linux (have not tried Windows). Note that I do not have the OpenH264 library installed separately.
Any ideas on this discrepancy? I would have expected the above snippet to fail, if the included ffmpeg is LGPL.
Activity
[-]Clarification on H264 support of included ffmpeg build[/-][+]Clarification on H264 support of included ffmpeg[/+]alalek commentedon Jun 23, 2022
FFmpeg has LGPL H264 builtin decoder. No problem is here.
FFmpeg doesn't have builtin LGPL H264 encoder. But it can use external encoders, like x264 (GPL), OpenH264 (BSD), etc.
On Windows OpenH264 is used (if available - downloaded by user from OpenH264 site).
On Linux status @asenyaev could clarify.
mdsmarte commentedon Jun 28, 2022
Thank you for the clarification!