avformat/evc: Don't cast const away, avoid loop

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavformat/evc.h

@@ -23,16 +23,17 @@
 #define AVFORMAT_EVC_H
 
 #include <stdint.h>
+
+#include "libavutil/intreadwrite.h"
 #include "libavutil/rational.h"
 #include "libavcodec/evc.h"
 #include "avio.h"
 
-static inline int evc_get_nalu_type(const uint8_t *bits, int bits_size)
+static inline int evc_get_nalu_type(const uint8_t *p, int bits_size)
 {
     int unit_type_plus1 = 0;
 
     if (bits_size >= EVC_NALU_HEADER_SIZE) {
-        unsigned char *p = (unsigned char *)bits;
         // forbidden_zero_bit
         if ((p[0] & 0x80) != 0)   // Cannot get bitstream information. Malformed bitstream.
             return -1;
@@ -46,16 +47,10 @@ static inline int evc_get_nalu_type(const uint8_t *bits, int bits_size)
 
 static inline uint32_t evc_read_nal_unit_length(const uint8_t *bits, int bits_size)
 {
-    uint32_t nalu_len = 0;
-
-    if (bits_size >= EVC_NALU_LENGTH_PREFIX_SIZE) {
-        unsigned char *p = (unsigned char *)bits;
-
-        for (int i = 0; i < EVC_NALU_LENGTH_PREFIX_SIZE; i++)
-            nalu_len = (nalu_len << 8) | p[i];
-    }
+    if (bits_size >= EVC_NALU_LENGTH_PREFIX_SIZE)
+        return AV_RB32(bits);
 
-    return nalu_len;
+    return 0;
 }
 
 /**