[FFmpeg-trac] #8659(avdevice:new): av_display_rotation_set() has no effect in android_camera

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#8659: av_display_rotation_set() has no effect in android_camera
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             Reporter:  juha-h          |                     Type:  defect
               Status:  new             |                 Priority:  normal
            Component:  avdevice        |                  Version:  4.2
             Keywords:  android_camera  |               Blocked By:
             Blocking:                  |  Reproduced by developer:  0
Analyzed by developer:  0               |
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 I'm using ffmpeg android_camera device as video source in my open source
 baresip VoIP app.

 If I make a call by holding the device upright (portrait), video from the
 front facing camera of the device has been rotated clockwise 90 degrees
 from portrait orientation.

 libavdevice/android_camera.c has this piece of code related to rotation:

   av_display_rotation_set(display_matrix, ctx->sensor_orientation);

   if (ctx->lens_facing == ACAMERA_LENS_FACING_FRONT) {
       av_display_matrix_flip(display_matrix, 1, 0);
   }

 I added debug to it and found that ctx->sensor_orientation has value
 270.0. It is correct value, since according to Android reference
 CameraCharacteristics.SENSOR_ORIENTATION means:

   The orientation of the camera image. The value is the angle that the
   camera image needs to be rotated clockwise so it shows correctly on
   the display in its natural orientation. It should be 0, 90, 180, or
   270.

 If av_display_rotation_set(display_matrix, ctx->sensor_orientation) call
 would work correctly, 90 + 270 = 360, and rotation of the video from the
 camera would be as it should be, i.e., upright.  Now it is 90 degrees from
 portrait, i.e., av_display_rotation_set() has no effect.

 I made more tests by replacing ctx->sensor_orientation argument with
 various constant values, eg. 0.0, 90.0, 180.0, etc, and noticed that the
 call has no effect: video is always rotated 90 degrees from portrait.

 So, I'm suspecting that there is a bug, which causes
 av_display_rotation_set() call to have no effect in android_camera.c.

 If needed I'm ready to make more tests and try possible patches.

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Ticket URL: <https://trac.ffmpeg.org/ticket/8659>
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