asfdec: handle the case when the stream index has an invalid value better

The demuxer returned INVALIDDATA and failed to demux the remaining data
when an invalid stream index was read, now it just skips the asf packet
for the stream with an invalid stream index and continues demuxing.

Reported-By: Hendrik Leppkes
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavformat/asfdec.c

@@ -1276,8 +1276,16 @@ static int asf_read_payload(AVFormatContext *s, AVPacket *pkt)
                 break;
             }
         }
-        if (!asf_pkt)
-            return AVERROR_INVALIDDATA;
+        if (!asf_pkt) {
+            if (asf->packet_offset + asf->packet_size <= asf->data_offset + asf->data_size) {
+                avio_seek(pb, asf->packet_offset + asf->packet_size, SEEK_SET);
+                av_log(s, AV_LOG_WARNING, "Skipping the stream with the invalid stream index %d.\n",
+                       asf->stream_index);
+                return AVERROR(EAGAIN);
+            } else
+                return AVERROR_INVALIDDATA;
+        }
+
         if (stream_num >> 7)
             asf_pkt->flags |= AV_PKT_FLAG_KEY;
         READ_LEN(asf->prop_flags & ASF_PL_MASK_MEDIA_OBJECT_NUMBER_LENGTH_FIELD_SIZE,
@@ -1418,8 +1426,14 @@ static int asf_read_packet(AVFormatContext *s, AVPacket *pkt)
             else
                 asf->state = READ_MULTI;
         }
-        if ((ret = asf_read_payload(s, pkt)) < 0)
+        ret = asf_read_payload(s, pkt);
+        if (ret == AVERROR(EAGAIN)) {
+            asf->state = PARSE_PACKET_HEADER;
+            continue;
+        }
+        else if (ret < 0)
             return ret;
+
         switch (asf->state) {
         case READ_SINGLE:
             if (!asf->sub_left)