avcodec/elbg: Add persistent ELBGContext

It will be used in future commits to avoid having to allocate and free
all the buffers used.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/libavcodec/elbg.h b/libavcodec/elbg.h
index a9a19aa5e4..abeeb4ff44 100644
--- a/libavcodec/elbg.h
+++ b/libavcodec/elbg.h
@@ -23,11 +23,16 @@
 
 #include "libavutil/lfg.h"
 
+struct ELBGContext;
+
 /**
  * Implementation of the Enhanced LBG Algorithm
  * Based on the paper "Neural Networks 14:1219-1237" that can be found in
  * http://citeseer.ist.psu.edu/patan01enhanced.html .
  *
+ * @param ctx  A pointer to a pointer to an already allocated ELBGContext
+ *             or a pointer to NULL. In the latter case, this function
+ *             will allocate an ELBGContext and put a pointer to it in `*ctx`.
  * @param points Input points.
  * @param dim Dimension of the points.
  * @param numpoints Num of points in **points.
@@ -38,8 +43,13 @@
  * @param rand_state A random number generator state. Should be already initialized by av_lfg_init().
  * @return < 0 in case of error, 0 otherwise
  */
-int avpriv_do_elbg(int *points, int dim, int numpoints, int *codebook,
-                   int num_cb, int num_steps, int *closest_cb,
-               AVLFG *rand_state);
+int avpriv_elbg_do(struct ELBGContext **ctx, int *points, int dim,
+                   int numpoints, int *codebook, int num_cb, int num_steps,
+                   int *closest_cb, AVLFG *rand_state);
+
+/**
+ * Free an ELBGContext and reset the pointer to it.
+ */
+void avpriv_elbg_free(struct ELBGContext **ctx);
 
 #endif /* AVCODEC_ELBG_H */