1 files changed, 52 insertions, 3 deletions

diff --git a/libavformat/flvdec.c b/libavformat/flvdec.c
index 01c67b48a5..d2b09b27e5 100644
--- a/libavformat/flvdec.c
+++ b/libavformat/flvdec.c
@@ -39,12 +39,20 @@
 #define KEYFRAMES_TIMESTAMP_TAG  "times"
 #define KEYFRAMES_BYTEOFFSET_TAG "filepositions"
 
+#define VALIDATE_INDEX_TS_THRESH 2500
+
 typedef struct {
     int wrong_dts; ///< wrong dts due to negative cts
     uint8_t *new_extradata[2];
     int      new_extradata_size[2];
     int      last_sample_rate;
     int      last_channels;
+    struct {
+        int64_t dts;
+        int64_t pos;
+    } validate_index[2];
+    int validate_next;
+    int validate_count;
 } FLVContext;
 
 static int flv_probe(AVProbeData *p)
@@ -137,6 +145,7 @@ static int amf_get_string(AVIOContext *ioc, char *buffer, int buffsize) {
 }
 
 static int parse_keyframes_index(AVFormatContext *s, AVIOContext *ioc, AVStream *vstream, int64_t max_pos) {
+    FLVContext *flv = s->priv_data;
     unsigned int arraylen = 0, timeslen = 0, fileposlen = 0, i;
     double num_val;
     char str_val[256];
@@ -206,11 +215,17 @@ static int parse_keyframes_index(AVFormatContext *s, AVIOContext *ioc, AVStream
         }
     }
 
-    if (!ret && timeslen == fileposlen)
-        for (i = 0; i < fileposlen; i++)
+    if (!ret && timeslen == fileposlen) {
+        for (i = 0; i < fileposlen; i++) {
             av_add_index_entry(vstream, filepositions[i], times[i]*1000,
                                0, 0, AVINDEX_KEYFRAME);
-    else
+            if (i < 2) {
+                flv->validate_index[i].pos = filepositions[i];
+                flv->validate_index[i].dts = times[i] * 1000;
+                flv->validate_count = i + 1;
+            }
+        }
+    } else
         av_log(s, AV_LOG_WARNING, "Invalid keyframes object, skipping.\n");
 
 finish:
@@ -434,6 +449,22 @@ static int flv_queue_extradata(FLVContext *flv, AVIOContext *pb, int stream,
     return 0;
 }
 
+static void clear_index_entries(AVFormatContext *s, int64_t pos)
+{
+    int i, j, out;
+    av_log(s, AV_LOG_WARNING, "Found invalid index entries, clearing the index.\n");
+    for (i = 0; i < s->nb_streams; i++) {
+        AVStream *st = s->streams[i];
+        /* Remove all index entries that point to >= pos */
+        out = 0;
+        for (j = 0; j < st->nb_index_entries; j++) {
+            if (st->index_entries[j].pos < pos)
+                st->index_entries[out++] = st->index_entries[j];
+        }
+        st->nb_index_entries = out;
+    }
+}
+
 static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     FLVContext *flv = s->priv_data;
@@ -455,6 +486,22 @@ static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
     avio_skip(s->pb, 3); /* stream id, always 0 */
     flags = 0;
 
+    if (flv->validate_next < flv->validate_count) {
+        int64_t validate_pos = flv->validate_index[flv->validate_next].pos;
+        if (pos == validate_pos) {
+            if (FFABS(dts - flv->validate_index[flv->validate_next].dts) <=
+                VALIDATE_INDEX_TS_THRESH) {
+                flv->validate_next++;
+            } else {
+                clear_index_entries(s, validate_pos);
+                flv->validate_count = 0;
+            }
+        } else if (pos > validate_pos) {
+            clear_index_entries(s, validate_pos);
+            flv->validate_count = 0;
+        }
+    }
+
     if(size == 0)
         continue;
 
@@ -633,6 +680,8 @@ leave:
 static int flv_read_seek(AVFormatContext *s, int stream_index,
     int64_t ts, int flags)
 {
+    FLVContext *flv = s->priv_data;
+    flv->validate_count = 0;
     return avio_seek_time(s->pb, stream_index, ts, flags);
 }