dav1d: add event flags to the decoding process

And a function to fetch them. Should be useful to signal changes in the
bitstream the user may want to know about.

Starting with two flags, DAV1D_EVENT_FLAG_NEW_SEQUENCE and
DAV1D_EVENT_FLAG_NEW_OP_PARAMS_INFO, which signal the presence of an updated
sequence header in the last returned (or to be returned) picture.

1 files changed, 29 insertions, 0 deletions

diff --git a/include/dav1d/dav1d.h b/include/dav1d/dav1d.h
index 165e1c0..97852dc 100644
--- a/include/dav1d/dav1d.h
+++ b/include/dav1d/dav1d.h
@@ -202,6 +202,35 @@ DAV1D_API void dav1d_close(Dav1dContext **c_out);
  */
 DAV1D_API void dav1d_flush(Dav1dContext *c);
 
+enum Dav1dEventFlags {
+    /**
+     * The last returned picture contains a reference to a new Sequence Header,
+     * either because it's the start of a new coded sequence, or the decoder was
+     * flushed before it was generated.
+     */
+    DAV1D_EVENT_FLAG_NEW_SEQUENCE =       1 << 0,
+    /**
+     * The last returned picture contains a reference to a Sequence Header with
+     * new operating parameters information for the current coded sequence.
+     */
+    DAV1D_EVENT_FLAG_NEW_OP_PARAMS_INFO = 1 << 1,
+};
+
+/**
+ * Fetch a combination of DAV1D_EVENT_FLAG_* event flags generated by the decoding
+ * process.
+ *
+ * @param c Input decoder instance.
+ * @param flags Where to write the flags.
+ *
+ * @return 0 on success, or < 0 (a negative DAV1D_ERR code) on error.
+ *
+ * @note Calling this function will clear all the event flags currently stored in
+ *       the decoder.
+ *
+ */
+DAV1D_API int dav1d_get_event_flags(Dav1dContext *c, enum Dav1dEventFlags *flags);
+
 # ifdef __cplusplus
 }
 # endif