avfilter/af_astats: rework sample loops

The channel loop is now the outer loop for both planar and interleaved. This is
needed by the next patch, and the speed difference is negligable if any.
Signed-off-by: Marton Balint <cus@passwd.hu>

libavfilter/af_astats.c

@@ -410,17 +410,18 @@ static void set_metadata(AudioStatsContext *s, AVDictionary **metadata)
     for (int c = 0; c < channels; c++) {                                        \
         ChannelStats *p = &s->chstats[c];                                       \
         const type *src = (const type *)data[c];                                \
-        for (int i = 0; i < samples; i++, src++)                                \
+        const type * const srcend = src + samples;                              \
+        for (; src < srcend; src++)                                             \
             update_stat(s, p, double_sample, normalized_sample, int_sample);    \
     }
 
-#define UPDATE_STATS_I(type, double_sample, normalized_sample, int_sample)                    \
-    {                                                                                         \
-        const type *src = (const type *)data[0];                                              \
-        for (int i = 0; i < samples; i++) {                                                   \
-            for (int c = 0; c < channels; c++, src++)                                         \
-                update_stat(s, &s->chstats[c], double_sample, normalized_sample, int_sample); \
-        }                                                                                     \
+#define UPDATE_STATS_I(type, double_sample, normalized_sample, int_sample)      \
+    for (int c = 0; c < channels; c++) {                                        \
+        ChannelStats *p = &s->chstats[c];                                       \
+        const type *src = (const type *)data[0];                                \
+        const type * const srcend = src + samples * channels;                   \
+        for (src += c; src < srcend; src += channels)                           \
+            update_stat(s, p, double_sample, normalized_sample, int_sample);    \
     }
 
 #define UPDATE_STATS(planar, type, sample, normalizer_suffix, int_sample) \