Video rotation metadata

[miguel-lorenzo]

I am getting this warning when reading videos from mobile phones

imageio_ffmpeg - WARNING - The frame size for reading (480, 720) is different from the source frame size (720, 480).

This means I have to rotate frames either 90º or 270º.

ffmpeg -i provides such rotation info of videos, For example:

ffmpeg -i myrotatedMOV.mov
....

Duration: 00:00:14.31, start: 0.000000, bitrate: 778 kb/s
    Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 480x360, 702 kb/s, 29.98 fps, 30 tbr, 600 tbn, 1200 tbc
    Metadata:
      rotate          : 180
      creation_time   : 2013-01-09 12:47:36
      handler_name    : Core Media Data Handler
    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, s16, 62 kb/s
    Metadata:
      creation_time   : 2013-01-09 12:47:36
      handler_name    : Core Media Data Handler

How can I get such information with imageio_ffmpeg? Tried _get_metadata() function but is not there

[almarklein]

Interesting. imageio-ffmpeg does not consider the rotation at all at the moment. We should probably read that metadata info and deal with it appropriately. I think that ideally it should just produce the images in the correct shape, so there should be no need for the user to see whether the video was stored rotated.

[almarklein]

How can I get such information with imageio_ffmpeg?

At the moment you can't.

[almarklein]

As a first step, it should be possible to add code here to add the rotation info to the metadata. That way users at least have a way to deal with it.

[miguel-lorenzo]

This code does it.

    # get the rotation
    reo_rotation = re.compile('rotate\s+:\s([0-9]+)')
    match = reo_rotation.search(text)
    rotation = 0
    if match is not None:
        rotation = match.groups()[0]
    meta["rotation"] = rotation

Check my PR please https://github.com/imageio/imageio-ffmpeg/pull/39

[hmaarrfk]

I think this can likely get closed.