avidec: calculate missing bitrates from index

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/avidec.c

@@ -379,6 +379,46 @@ static void avi_read_nikon(AVFormatContext *s, uint64_t end)
     }
 }
 
+static int calculate_bitrate(AVFormatContext *s)
+{
+    AVIContext *avi = s->priv_data;
+    int i, j;
+    int64_t lensum = 0;
+    int64_t maxpos = 0;
+
+    for (i = 0; i<s->nb_streams; i++) {
+        int64_t len = 0;
+        AVStream *st = s->streams[i];
+
+        if (!st->nb_index_entries)
+            continue;
+
+        for (j = 0; j < st->nb_index_entries; j++)
+            len += st->index_entries[j].size;
+        maxpos = FFMAX(maxpos, st->index_entries[j-1].pos);
+        lensum += len;
+    }
+    if (maxpos < avi->io_fsize*9/10) // index doesnt cover the whole file
+        return 0;
+    if (lensum*9/10 > maxpos || lensum < maxpos*9/10) // frame sum and filesize mismatch
+        return 0;
+
+    for (i = 0; i<s->nb_streams; i++) {
+        int64_t len = 0;
+        AVStream *st = s->streams[i];
+        int64_t duration;
+
+        for (j = 0; j < st->nb_index_entries; j++)
+            len += st->index_entries[j].size;
+
+        if (st->nb_index_entries < 2 || st->codec->bit_rate > 0)
+            continue;
+        duration = st->index_entries[j-1].timestamp - st->index_entries[0].timestamp;
+        st->codec->bit_rate = av_rescale(8*len, st->time_base.den, duration * st->time_base.num);
+    }
+    return 1;
+}
+
 static int avi_read_header(AVFormatContext *s)
 {
     AVIContext *avi = s->priv_data;
@@ -863,6 +903,7 @@ fail:
 
     if (!avi->index_loaded && pb->seekable)
         avi_load_index(s);
+    calculate_bitrate(s);
     avi->index_loaded    |= 1;
     avi->non_interleaved |= guess_ni_flag(s) | (s->flags & AVFMT_FLAG_SORT_DTS);