[FFmpeg-devel] [PATCH v5 2/2] fftools/ffmpeg: Add stream metadata from first frame's metadata

Jun Li junli1026 at gmail.com
Thu May 9 09:05:25 EEST 2019


Fix #6945
'Orientation' field from EXIF tags in first decoded frame is extracted
as stream side data so that ffmpeg can apply auto-rotation.
---
 fftools/ffmpeg.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 01f04103cf..73f185a2d1 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -2341,6 +2341,64 @@ static int decode_audio(InputStream *ist, AVPacket *pkt, int *got_output,
     return err < 0 ? err : ret;
 }
 
+static int set_metadata_from_1stframe(InputStream* ist, AVFrame* frame) 
+{
+    AVDictionaryEntry *entry = NULL;
+    int orientation = 0, size = 0;
+    int32_t* sd = NULL;
+
+    sd = (int32_t*)av_stream_get_side_data(ist->st, AV_PKT_DATA_DISPLAYMATRIX, &size);
+    if (sd) // stream already contains display matrix
+        return 0;
+
+    // read exif orientation data
+    entry = av_dict_get(frame->metadata, "Orientation", NULL, 0);
+    if (entry) {
+        orientation = atoi(entry->value);
+        sd = (int32_t*)av_stream_new_side_data(ist->st, AV_PKT_DATA_DISPLAYMATRIX, 4 * 9);
+        if (!sd)
+            return AVERROR(ENOMEM);
+        memset(sd, 0, 4 * 9);
+        switch (orientation)
+        {
+            case 1: // horizontal (normal)
+                av_display_rotation_set(sd, 0.0);
+                break;
+            case 2: // mirror horizontal
+                av_display_rotation_set(sd, 0.0);
+                av_display_matrix_flip(sd, 1, 0);
+                break;
+            case 3: // rotate 180
+                av_display_rotation_set(sd, 180.0);
+                break;
+            case 4: // mirror vertical
+                av_display_rotation_set(sd, 0.0);
+                av_display_matrix_flip(sd, 0, 1);
+                break;
+            case 5: // mirror horizontal and rotate 270 CW
+                av_display_rotation_set(sd, 270.0);
+                av_display_matrix_flip(sd, 0, 1);
+                break;
+            case 6: // rotate 90 CW
+                av_display_rotation_set(sd, 90.0);
+                break;
+            case 7: // mirror horizontal and rotate 90 CW
+                av_display_rotation_set(sd, 90.0);
+                av_display_matrix_flip(sd, 0, 1);
+                break;
+            case 8: // rotate 270 CW
+                av_display_rotation_set(sd, 270.0);
+                break;
+            default:
+                av_display_rotation_set(sd, 0.0);
+                av_log(ist->dec_ctx, AV_LOG_WARNING,    
+                    "Exif orientation data out of range: %i. Set to default value: horizontal(normal).\n", orientation);
+                break;
+        }
+    }
+    return 0;
+}
+
 static int decode_video(InputStream *ist, AVPacket *pkt, int *got_output, int64_t *duration_pts, int eof,
                         int *decode_failed)
 {
@@ -2423,7 +2481,10 @@ static int decode_video(InputStream *ist, AVPacket *pkt, int *got_output, int64_
         decoded_frame->top_field_first = ist->top_field_first;
 
     ist->frames_decoded++;
-
+    if (ist->frames_decoded == 1 &&
+        ((err = set_metadata_from_1stframe(ist, decoded_frame)) < 0))
+        goto fail;
+    
     if (ist->hwaccel_retrieve_data && decoded_frame->format == ist->hwaccel_pix_fmt) {
         err = ist->hwaccel_retrieve_data(ist->dec_ctx, decoded_frame);
         if (err < 0)
-- 
2.17.1



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