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Issue created by Sebastian Wallkötter@FirefoxMetzgerContributor4 of 6 checklist items completed4/6 checklist items

v10 no longer writes "rotate" metadata flag

Overview

As of v10.0.0 the stream metadata flag rotate is no longer written to file. This may affect other metadata fields; however, for this one specifically, we have a unit-test downstream so I know for sure that it is affected.

Expected behavior

Setting a field in a video stream's metadata dict causes it to be written to the file.

Actual behavior

Stream-level metadata (at least the rotation flag) is no longer written.

Reproduction

import av
import numpy as np

print(f"PyAV version: {av.__version__}")

with av.open("test.mp4", "w") as container:
    container.metadata["comment"] = "This video has a rotation flag."

    stream = container.add_stream("libx264", 24)
    stream.metadata["rotate"] = "90"

    for _ in range(24):
        frame = av.VideoFrame.from_ndarray(np.ones((128, 128, 3), dtype=np.uint8))
        for packet in stream.encode(frame):
            container.mux(packet)

    for packet in stream.encode():
        container.mux(packet)

with av.open("test.mp4") as container:
    print(container.metadata)
    video_stream = container.streams.video[0]
    print(video_stream.metadata)

Using av v9.2 the above snippet produces:

PyAV version: 9.2.0
{'major_brand': 'isom', 'minor_version': '512', 'compatible_brands': 'isomiso2avc1mp41', 'encoder': 'Lavf58.76.100', 'comment': 'This video has a rotation flag.'}
{'rotate': '90', 'language': 'und', 'handler_name': 'VideoHandler', 'vendor_id': '[0][0][0][0]'}

However, when switching to v10 it produces:

PyAV version: 10.0.0
{'major_brand': 'isom', 'minor_version': '512', 'compatible_brands': 'isomiso2avc1mp41', 'encoder': 'Lavf59.27.100', 'comment': 'This video has a rotation flag.'}
{'language': 'und', 'handler_name': 'VideoHandler', 'vendor_id': '[0][0][0][0]'}

Versions

  • OS: Windows 11 and Ubuntu 20.04
  • PyAV runtime:
PyAV v10.0.0
library configuration: --disable-static --enable-shared --libdir=/c/cibw/vendor/lib --prefix=/c/cibw/vendor --disable-alsa --disable-doc --disable-mediafoundation --enable-fontconfig --enable-gmp --disable-gnutls --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libdav1d --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --disable-libxcb --enable-libxml2 --enable-libxvid --enable-lzma --enable-version3 --enable-zlib
library license: GPL version 3 or later
libavcodec     59. 37.100
libavdevice    59.  7.100
libavfilter     8. 44.100
libavformat    59. 27.100
libavutil      57. 28.100
libswresample   4.  7.100
libswscale      6.  7.100
  • FFmpeg: (pypi shipped binary)

Research

I have done the following: