avformat/flvdec: Support live flv / NGINX RTMP streams

Fixes Ticket3553

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

libavformat/allformats.c

@@ -123,6 +123,7 @@ void av_register_all(void)
     REGISTER_MUXDEMUX(FLAC,             flac);
     REGISTER_DEMUXER (FLIC,             flic);
     REGISTER_MUXDEMUX(FLV,              flv);
+    REGISTER_DEMUXER (LIVE_FLV,         live_flv);
     REGISTER_DEMUXER (FOURXM,           fourxm);
     REGISTER_MUXER   (FRAMECRC,         framecrc);
     REGISTER_MUXER   (FRAMEMD5,         framemd5);

libavformat/flvdec.c

@@ -56,21 +56,35 @@ typedef struct {
     int searched_for_end;
 } FLVContext;
 
-static int flv_probe(AVProbeData *p)
+static int probe(AVProbeData *p, int live)
 {
-    const uint8_t *d;
+    const uint8_t *d = p->buf;
+    unsigned offset = AV_RB32(d + 5);
 
-    d = p->buf;
     if (d[0] == 'F' &&
         d[1] == 'L' &&
         d[2] == 'V' &&
         d[3] < 5 && d[5] == 0 &&
-        AV_RB32(d + 5) > 8) {
-        return AVPROBE_SCORE_MAX;
+        offset + 100 < p->buf_size &&
+        offset > 8) {
+        int is_live = !memcmp(d + offset + 40, "NGINX RTMP", 10);
+
+        if (live == is_live)
+            return AVPROBE_SCORE_MAX;
     }
     return 0;
 }
 
+static int flv_probe(AVProbeData *p)
+{
+    return probe(p, 0);
+}
+
+static int live_flv_probe(AVProbeData *p)
+{
+    return probe(p, 1);
+}
+
 static AVStream *create_stream(AVFormatContext *s, int codec_type)
 {
     AVStream *st = avformat_new_stream(s, NULL);
@@ -1049,3 +1063,24 @@ AVInputFormat ff_flv_demuxer = {
     .extensions     = "flv",
     .priv_class     = &flv_class,
 };
+
+static const AVClass live_flv_class = {
+    .class_name = "flvdec",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVInputFormat ff_live_flv_demuxer = {
+    .name           = "live_flv",
+    .long_name      = NULL_IF_CONFIG_SMALL("live RTMP FLV (Flash Video)"),
+    .priv_data_size = sizeof(FLVContext),
+    .read_probe     = live_flv_probe,
+    .read_header    = flv_read_header,
+    .read_packet    = flv_read_packet,
+    .read_seek      = flv_read_seek,
+    .read_close     = flv_read_close,
+    .extensions     = "flv",
+    .priv_class     = &live_flv_class,
+    .flags          = AVFMT_TS_DISCONT
+};