[FFmpeg-devel] [PATCH v8 2/2] fftools/ffmpeg: add exif orientation support per frame's metadata

[Michael Niedermayer]

On Thu, Jun 06, 2019 at 08:28:15PM -0700, Jun Li wrote:
> Fix #6945
> Rotate or/and flip frame according to frame's metadata orientation
> ---
>  fftools/ffmpeg.c        |  5 +++--
>  fftools/ffmpeg.h        |  8 ++++++++
>  fftools/ffmpeg_filter.c | 36 +++++++++++++++++++++++++++++++-----
>  3 files changed, 42 insertions(+), 7 deletions(-)
> 
> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> index 01f04103cf..bc0cece59d 100644
> --- a/fftools/ffmpeg.c
> +++ b/fftools/ffmpeg.c
> @@ -2141,8 +2141,9 @@ static int ifilter_send_frame(InputFilter *ifilter, AVFrame *frame)
>                         ifilter->channel_layout != frame->channel_layout;
>          break;
>      case AVMEDIA_TYPE_VIDEO:
> -        need_reinit |= ifilter->width  != frame->width ||
> -                       ifilter->height != frame->height;
> +        need_reinit |= ifilter->width       != frame->width ||
> +                       ifilter->height      != frame->height ||
> +                       ifilter->orientation != get_frame_orientation(frame);
>          break;
>      }
>  
> diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
> index 7b6f802082..7324813ce3 100644
> --- a/fftools/ffmpeg.h
> +++ b/fftools/ffmpeg.h
> @@ -232,6 +232,12 @@ typedef struct OptionsContext {
>      int        nb_enc_time_bases;
>  } OptionsContext;
>  
> +enum OrientationType {
> +    ORIENTATION_NONE,
> +    ORIENTATION_AUTO_FLIP,
> +    ORIENTATION_AUTO_TRANSPOSE
> +};
> +
>  typedef struct InputFilter {
>      AVFilterContext    *filter;
>      struct InputStream *ist;
> @@ -245,6 +251,7 @@ typedef struct InputFilter {
>      int format;
>  
>      int width, height;
> +    enum OrientationType orientation;
>      AVRational sample_aspect_ratio;
>  
>      int sample_rate;
> @@ -649,6 +656,7 @@ int init_complex_filtergraph(FilterGraph *fg);
>  void sub2video_update(InputStream *ist, AVSubtitle *sub);
>  
>  int ifilter_parameters_from_frame(InputFilter *ifilter, const AVFrame *frame);
> +enum OrientationType get_frame_orientation(const AVFrame* frame);
>  
>  int ffmpeg_parse_options(int argc, char **argv);
>  
> diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
> index 72838de1e2..790751f47f 100644
> --- a/fftools/ffmpeg_filter.c
> +++ b/fftools/ffmpeg_filter.c
> @@ -743,6 +743,28 @@ static int sub2video_prepare(InputStream *ist, InputFilter *ifilter)
>      return 0;
>  }
>  
> +enum OrientationType get_frame_orientation(const AVFrame *frame)
> +{
> +    AVDictionaryEntry *entry = NULL;
> +    int orientation = 0;
> +    
> +    // read exif orientation data
> +    entry = av_dict_get(frame->metadata, "Orientation", NULL, 0);
> +    if (entry && entry->value)
> +        orientation = atoi(entry->value);

what if entry->value equals "The cow says moo" ?
This is of course a silly example but the following code would not detect it as an error
as atoi would return 0 
or is there something that prevents this case ?


> +
> +    if (orientation > 8 || orientation < 0) {
> +        av_log(NULL, AV_LOG_WARNING, "Invalid frame orientation: %i, skip it.\n", orientation);
> +        return ORIENTATION_NONE;
> +    } else if (orientation <= 1) {
> +        return ORIENTATION_NONE;
> +    } else if (orientation <= 4) {
> +        return ORIENTATION_AUTO_FLIP;
> +    } else {
> +        return ORIENTATION_AUTO_TRANSPOSE;
> +    }
> +}

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

"Nothing to hide" only works if the folks in power share the values of
you and everyone you know entirely and always will -- Tom Scott

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