Forward Error Correction (#24)

* Preperation for FEC by adding new queue which buffers whole frames

* Add code for creating recovered RTP packet

* Add checks before repair missing packets

* Initial implementation for single FEC packet

* Implement FEC for multiple packets

reedsolomon/rs.h

@@ -0,0 +1,42 @@
+#ifndef __RS_H_
+#define __RS_H_
+
+/* use small value to save memory */
+#define DATA_SHARDS_MAX 255
+
+typedef struct _reed_solomon {
+    int data_shards;
+    int parity_shards;
+    int shards;
+    unsigned char* m;
+    unsigned char* parity;
+} reed_solomon;
+
+/**
+ * MUST initial one time
+ * */
+void reed_solomon_init(void);
+
+reed_solomon* reed_solomon_new(int data_shards, int parity_shards);
+void reed_solomon_release(reed_solomon* rs);
+
+/**
+ * encode a big size of buffer
+ * input:
+ * rs
+ * nr_shards: assert(0 == nr_shards % rs->data_shards)
+ * shards[nr_shards][block_size]
+ * */
+int reed_solomon_encode(reed_solomon* rs, unsigned char** shards, int nr_shards, int block_size);
+
+/**
+ * reconstruct a big size of buffer
+ * input:
+ * rs
+ * nr_shards: assert(0 == nr_shards % rs->data_shards)
+ * shards[nr_shards][block_size]
+ * marks[nr_shards] marks as errors
+ * */
+int reed_solomon_reconstruct(reed_solomon* rs, unsigned char** shards, unsigned char* marks, int nr_shards, int block_size);
+#endif
+