mov: Wrap stsc index and count compare in a separate function

libavformat/mov.c

@@ -1961,12 +1961,17 @@ static int mov_read_stsc(MOVContext *c, AVIOContext *pb, MOVAtom atom)
     return 0;
 }
 
+static inline int mov_stsc_index_valid(int index, int count)
+{
+    return index + 1 < count;
+}
+
 /* Compute the samples value for the stsc entry at the given index. */
 static inline int mov_get_stsc_samples(MOVStreamContext *sc, int index)
 {
     int chunk_count;
 
-    if (index < sc->stsc_count - 1)
+    if (mov_stsc_index_valid(index, sc->stsc_count))
         chunk_count = sc->stsc_data[index + 1].first - sc->stsc_data[index].first;
     else
         chunk_count = sc->chunk_count - (sc->stsc_data[index].first - 1);
@@ -2333,7 +2338,7 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
 
         for (i = 0; i < sc->chunk_count; i++) {
             current_offset = sc->chunk_offsets[i];
-            while (stsc_index + 1 < sc->stsc_count &&
+            while (mov_stsc_index_valid(stsc_index, sc->stsc_count) &&
                 i + 1 == sc->stsc_data[stsc_index + 1].first)
                 stsc_index++;
             for (j = 0; j < sc->stsc_data[stsc_index].count; j++) {
@@ -2413,7 +2418,7 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
                 count = (chunk_samples+1023) / 1024;
             }
 
-            if (i < sc->stsc_count - 1)
+            if (mov_stsc_index_valid(i, sc->stsc_count))
                 chunk_count = sc->stsc_data[i+1].first - sc->stsc_data[i].first;
             else
                 chunk_count = sc->chunk_count - (sc->stsc_data[i].first - 1);
@@ -2434,7 +2439,7 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
         // populate index
         for (i = 0; i < sc->chunk_count; i++) {
             current_offset = sc->chunk_offsets[i];
-            if (stsc_index + 1 < sc->stsc_count &&
+            if (mov_stsc_index_valid(stsc_index, sc->stsc_count) &&
                 i + 1 == sc->stsc_data[stsc_index + 1].first)
                 stsc_index++;
             chunk_samples = sc->stsc_data[stsc_index].count;
@@ -3680,7 +3685,7 @@ static int mov_read_packet(AVFormatContext *s, AVPacket *pkt)
         /* Keep track of the stsc index for the given sample, then check
         * if the stsd index is different from the last used one. */
         sc->stsc_sample++;
-        if (sc->stsc_index + 1 < sc->stsc_count &&
+        if (mov_stsc_index_valid(sc->stsc_index, sc->stsc_count) &&
             mov_get_stsc_samples(sc, sc->stsc_index) == sc->stsc_sample) {
             sc->stsc_index++;
             sc->stsc_sample = 0;