Re: [FFmpeg-devel] [PATCH 1/5] avformat/matroskaenc: Support rotations

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

Andreas Rheinhardt:
> Matroska supports orthogonal transformations (both pure rotations
> as well as reflections) via its 3D-projection elements, namely
> ProjectionPoseYaw (for a horizontal reflection) as well as
> ProjectionPoseRoll (for rotations). This commit adds support
> for this.
> 
> Support for this in the demuxer has been added in
> 937bb6bbc1e8654633737e69e403e95a37113058 and
> the sample used in the matroska-dovi-write-config8 FATE-test
> includes a displaymatrix indicating a rotation which is now
> properly written and read, thereby providing coverage for
> the relevant code in the muxer as well as the demuxer.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
> ---
> Honestly, I am not really sure how to handle the floating-point
> inaccuracies here (in atan2).
> 
>  libavformat/matroskaenc.c                  | 100 +++++++++++++++++----
>  tests/ref/fate/matroska-dovi-write-config8 |  13 ++-
>  2 files changed, 94 insertions(+), 19 deletions(-)
> 
> diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
> index 41e13b273d..c1f40b26e6 100644
> --- a/libavformat/matroskaenc.c
> +++ b/libavformat/matroskaenc.c
> @@ -1403,25 +1403,75 @@ static void mkv_write_video_color(EbmlWriter *writer, const AVStream *st,
>  }
>  
>  #define MAX_VIDEO_PROJECTION_ELEMS 6
> -static void mkv_write_video_projection(AVFormatContext *s, EbmlWriter *writer,
> -                                       const AVStream *st, uint8_t private[])
> +static void mkv_handle_rotation(void *logctx, const AVStream *st,
> +                                double *yaw, double *roll)
> +{
> +    const int32_t *matrix =
> +        (const int32_t*)av_stream_get_side_data(st, AV_PKT_DATA_DISPLAYMATRIX, NULL);
> +
> +    if (!matrix)
> +        return;
> +
> +    /* Check whether this is an affine transformation */
> +    if (matrix[2] || matrix[5])
> +        goto ignore;
> +
> +    /* This together with the checks below test whether
> +     * the upper-left 2x2 matrix is nonsingular. */
> +    if (!matrix[0] && !matrix[1])
> +        goto ignore;
> +
> +    /* We ignore the translation part of the matrix (matrix[6] and matrix[7])
> +     * as well as any scaling, i.e. we only look at the upper left 2x2 matrix.
> +     * We only accept matrices that are an exact multiple of an orthogonal one.
> +     * Apart from the multiple, every such matrix can be obtained by
> +     * potentially flipping in the x-direction (corresponding to yaw = 180)
> +     * followed by a rotation of (say) an angle phi in the counterclockwise
> +     * direction. The upper-left 2x2 matrix then looks like this:
> +     *         | (+/-)cos(phi) (-/+)sin(phi) |
> +     * scale * |                             |
> +     *         |      sin(phi)      cos(phi) |
> +     * The first set of signs in the first row apply in case of no flipping,
> +     * the second set applies in case of flipping. */
> +
> +    /* The casts to int64_t are needed because -INT32_MIN doesn't fit
> +     * in an int32_t. */
> +    if (matrix[0] == matrix[4] && -(int64_t)matrix[1] == matrix[3]) {
> +        /* No flipping case */
> +        *yaw = 0;
> +    } else if (-(int64_t)matrix[0] == matrix[4] && matrix[1] == matrix[3]) {
> +        /* Horizontal flip */
> +        *yaw = 180;
> +    } else {
> +ignore:
> +        av_log(logctx, AV_LOG_INFO, "Ignoring display matrix indicating "
> +               "non-orthogonal transformation.\n");
> +        return;
> +    }
> +    *roll = 180 / M_PI * atan2(matrix[3], matrix[4]);
> +
> +    /* We do not write a ProjectionType element indicating "rectangular",
> +     * because this is the default value. */
> +}
> +
> +static int mkv_handle_spherical(void *logctx, EbmlWriter *writer,
> +                                const AVStream *st, uint8_t private[],
> +                                double *yaw, double *pitch, double *roll)
>  {
>      const AVSphericalMapping *spherical =
>          (const AVSphericalMapping *)av_stream_get_side_data(st, AV_PKT_DATA_SPHERICAL,
>                                                              NULL);
>  
>      if (!spherical)
> -        return;
> +        return 0;
>  
>      if (spherical->projection != AV_SPHERICAL_EQUIRECTANGULAR      &&
>          spherical->projection != AV_SPHERICAL_EQUIRECTANGULAR_TILE &&
>          spherical->projection != AV_SPHERICAL_CUBEMAP) {
> -        av_log(s, AV_LOG_WARNING, "Unknown projection type\n");
> -        return;
> +        av_log(logctx, AV_LOG_WARNING, "Unknown projection type\n");
> +        return 0;
>      }
>  
> -    ebml_writer_open_master(writer, MATROSKA_ID_VIDEOPROJECTION);
> -
>      switch (spherical->projection) {
>      case AV_SPHERICAL_EQUIRECTANGULAR:
>      case AV_SPHERICAL_EQUIRECTANGULAR_TILE:
> @@ -1455,17 +1505,33 @@ static void mkv_write_video_projection(AVFormatContext *s, EbmlWriter *writer,
>          av_assert0(0);
>      }
>  
> -    if (spherical->yaw)
> -        ebml_writer_add_float(writer, MATROSKA_ID_VIDEOPROJECTIONPOSEYAW,
> -                              (double) spherical->yaw   / (1 << 16));
> -    if (spherical->pitch)
> -        ebml_writer_add_float(writer, MATROSKA_ID_VIDEOPROJECTIONPOSEPITCH,
> -                       (double) spherical->pitch / (1 << 16));
> -    if (spherical->roll)
> -        ebml_writer_add_float(writer, MATROSKA_ID_VIDEOPROJECTIONPOSEROLL,
> -                       (double) spherical->roll  / (1 << 16));
> +    *yaw   = (double) spherical->yaw   / (1 << 16);
> +    *pitch = (double) spherical->pitch / (1 << 16);
> +    *roll  = (double) spherical->roll  / (1 << 16);
>  
> -    ebml_writer_close_master(writer);
> +    return 1; /* Projection included */
> +}
> +
> +static void mkv_write_video_projection(void *logctx, EbmlWriter *wr,
> +                                       const AVStream *st, uint8_t private[])
> +{
> +    double yaw = 0, pitch = 0, roll = 0;
> +    int ret;
> +
> +    ebml_writer_open_master(wr, MATROSKA_ID_VIDEOPROJECTION);
> +
> +    ret = mkv_handle_spherical(logctx, wr, st, private, &yaw, &pitch, &roll);
> +    if (!ret)
> +        mkv_handle_rotation(logctx, st, &yaw, &roll);
> +
> +    if (yaw)
> +        ebml_writer_add_float(wr, MATROSKA_ID_VIDEOPROJECTIONPOSEYAW, yaw);
> +    if (pitch)
> +        ebml_writer_add_float(wr, MATROSKA_ID_VIDEOPROJECTIONPOSEPITCH, pitch);
> +    if (roll)
> +        ebml_writer_add_float(wr, MATROSKA_ID_VIDEOPROJECTIONPOSEROLL, roll);
> +
> +    ebml_writer_close_or_discard_master(wr);
>  }
>  
>  #define MAX_FIELD_ORDER_ELEMS 2
> diff --git a/tests/ref/fate/matroska-dovi-write-config8 b/tests/ref/fate/matroska-dovi-write-config8
> index bb22563eee..58eb454865 100644
> --- a/tests/ref/fate/matroska-dovi-write-config8
> +++ b/tests/ref/fate/matroska-dovi-write-config8
> @@ -1,5 +1,5 @@
> -09ff3c0a038eec0cdf4773929b24f41a *tests/data/fate/matroska-dovi-write-config8.matroska
> -3600606 tests/data/fate/matroska-dovi-write-config8.matroska
> +80d2b23a6f27ab28b02a907b37b9649c *tests/data/fate/matroska-dovi-write-config8.matroska
> +3600620 tests/data/fate/matroska-dovi-write-config8.matroska
>  #extradata 0:      551, 0xa18acf66
>  #extradata 1:        2, 0x00340022
>  #tb 0: 1/1000
> @@ -46,6 +46,15 @@
>  1,        395,        395,       23,      439, 0x7d85e4c9
>  [STREAM]
>  [SIDE_DATA]
> +side_data_type=Display Matrix
> +displaymatrix=
> +00000000:            0       65536           0
> +00000001:       -65536           0           0
> +00000002:            0           0  1073741824
> +
> +rotation=-90
> +[/SIDE_DATA]
> +[SIDE_DATA]
>  side_data_type=DOVI configuration record
>  dv_version_major=1
>  dv_version_minor=0

Will apply patches 1-5 of this patchset tomorrow unless there are
objections. Notice that I slightly modified the test added in 3/5 to now
also set a creation_time metadata to test a previously untested codepath.

- Andreas

_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".