avformat/avidec: Fix incorrect detection of badly interleaved avi

The method guess_ni_flag needs to divide timestamps in the index
by sample_size if it is set in order to compare different streams correctly.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/version.h

@@ -30,7 +30,7 @@
 
 #define LIBAVCODEC_VERSION_MAJOR 55
 #define LIBAVCODEC_VERSION_MINOR  18
-#define LIBAVCODEC_VERSION_MICRO 101
+#define LIBAVCODEC_VERSION_MICRO 102
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \

libavformat/avidec.c

@@ -1397,15 +1397,16 @@ static int guess_ni_flag(AVFormatContext *s){
 
         for (i=0; i<s->nb_streams; i++) {
             AVStream *st = s->streams[i];
+            AVIStream *ast = st->priv_data;
             int n= st->nb_index_entries;
             while (idx[i]<n && st->index_entries[idx[i]].pos < pos)
                 idx[i]++;
             if (idx[i] < n) {
-                min_dts = FFMIN(min_dts, av_rescale_q(st->index_entries[idx[i]].timestamp, st->time_base, AV_TIME_BASE_Q));
+                min_dts = FFMIN(min_dts, av_rescale_q(st->index_entries[idx[i]].timestamp/FFMAX(ast->sample_size, 1), st->time_base, AV_TIME_BASE_Q));
                 min_pos = FFMIN(min_pos, st->index_entries[idx[i]].pos);
             }
             if (idx[i])
-                max_dts = FFMAX(max_dts, av_rescale_q(st->index_entries[idx[i]-1].timestamp, st->time_base, AV_TIME_BASE_Q));
+                max_dts = FFMAX(max_dts, av_rescale_q(st->index_entries[idx[i]-1].timestamp/FFMAX(ast->sample_size, 1), st->time_base, AV_TIME_BASE_Q));
         }
         if(max_dts - min_dts > 2*AV_TIME_BASE) {
             av_free(idx);