avformat/mov: Only read the mfra size once during sidx parsing

On files with more than one sidx box, like live fragmented MP4
files, it was previously re-reading and seeking on every singl
sidx box, leading to extremely poor performance on larger files,
especially over the network.

Only do it on the first one, and stash its result.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/libavformat/isom.h b/libavformat/isom.h
index 41a9c64c11..78495fd336 100644
--- a/libavformat/isom.h
+++ b/libavformat/isom.h
@@ -291,6 +291,8 @@ typedef struct MOVContext {
     int decryption_key_len;
     int enable_drefs;
     int32_t movie_display_matrix[3][3]; ///< display matrix from mvhd
+    int have_read_mfra_size;
+    uint32_t mfra_size;
 } MOVContext;
 
 int ff_mp4_read_descr_len(AVIOContext *pb);