Re: [FFmpeg-devel] [PATCH, v2] avformat/mov: get heif image rotation from irot box

[James Almer <jamrial@gmail.com>]

On 5/27/2024 12:22 PM, Hacene Bouaroua wrote:
> parse irot box to get the transformative heif item rotation angle.
> 
> Signed-off-by: Hacene Bouaroua <hbouaroua@freebox.fr>
> ---
>   libavformat/avformat.h |  5 +++++
>   libavformat/isom.h     |  1 +
>   libavformat/mov.c      | 25 +++++++++++++++++++++++++
>   3 files changed, 31 insertions(+)
> 
> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> index 8afdcd9fd0..615650ddcb 100644
> --- a/libavformat/avformat.h
> +++ b/libavformat/avformat.h
> @@ -1077,6 +1077,11 @@ typedef struct AVStreamGroupTileGrid {
>        * final image before presentation.
>        */
>       int height;
> +    /**
> +     * the angle which the reconstructed image is initially rotated
> +     * (in anti-clockwise direction) in units of degrees.
> +     */
> +    int rotation;

This should probably be an AVRational (With range [-180.0, 180.0]), so 
you can easily pass av_q2d(rotation) to av_display_rotation_set().

>   } AVStreamGroupTileGrid;
>   
>   enum AVStreamGroupParamsType {
> diff --git a/libavformat/isom.h b/libavformat/isom.h
> index c0a5788e08..757e3f8738 100644
> --- a/libavformat/isom.h
> +++ b/libavformat/isom.h
> @@ -277,6 +277,7 @@ typedef struct HEIFItem {
>       int64_t extent_offset;
>       int width;
>       int height;
> +    int rotation;
>       int type;
>       int is_idat_relative;
>   } HEIFItem;
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 45eca74d1d..5f04e68f88 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -8398,6 +8398,27 @@ static int mov_read_ispe(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>       return 0;
>   }
>   
> +static int mov_read_irot(MOVContext *c, AVIOContext *pb, MOVAtom atom)
> +{
> +    uint32_t angle;
> +
> +    angle = avio_r8(pb);

avio_r8(pb) & 0x3. The upper bits are reserved.

> +
> +    av_log(c->fc, AV_LOG_TRACE, "irot: item_id %d, angle %u\n",
> +           c->cur_item_id, angle);
> +
> +    for (int i = 0; i < c->nb_heif_item; i++) {
> +        if (c->heif_item[i].item_id == c->cur_item_id) {
> +            // angle * 90 specifies the angle (in anti-clockwise direction)
> +            // in units of degrees.
> +            c->heif_item[i].rotation  = angle * 90; > +            break;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
>   static int mov_read_iprp(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>   {
>       typedef struct MOVAtoms {
> @@ -8615,6 +8636,7 @@ static const MOVParseTableEntry mov_default_parse_table[] = {
>   { MKTAG('i','d','a','t'), mov_read_idat },
>   { MKTAG('i','r','e','f'), mov_read_iref },
>   { MKTAG('i','s','p','e'), mov_read_ispe },
> +{ MKTAG('i','r','o','t'), mov_read_irot },
>   { MKTAG('i','p','r','p'), mov_read_iprp },
>   { MKTAG('i','i','n','f'), mov_read_iinf },
>   { MKTAG('a','m','v','e'), mov_read_amve }, /* ambient viewing environment box */
> @@ -9315,6 +9337,9 @@ static int read_image_grid(AVFormatContext *s, const HEIFGrid *grid,
>       tile_grid->width  = (flags & 1) ? avio_rb32(s->pb) : avio_rb16(s->pb);
>       tile_grid->height = (flags & 1) ? avio_rb32(s->pb) : avio_rb16(s->pb);
>   
> +    /* rotation */
> +    tile_grid->rotation = item->rotation;
> +
>       av_log(c->fc, AV_LOG_TRACE, "grid: grid_rows %d grid_cols %d output_width %d output_height %d\n",
>              tile_rows, tile_cols, tile_grid->width, tile_grid->height);
>   
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