avformat/mpegtsenc: check that not only first pts but also first dts is valid

Reviewed-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Limin Wang <lance.lmwang@gmail.com>

libavformat/mpegtsenc.c

@@ -232,7 +232,7 @@ typedef struct MpegTSWriteStream {
     int cc;
     int discontinuity;
     int payload_size;
-    int first_pts_checked; ///< first pts check needed
+    int first_timestamp_checked; ///< first pts/dts check needed
     int prev_payload_key;
     int64_t payload_pts;
     int64_t payload_dts;
@@ -1699,11 +1699,11 @@ static int mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
             dts += delay;
     }
 
-    if (!ts_st->first_pts_checked && pts == AV_NOPTS_VALUE) {
-        av_log(s, AV_LOG_ERROR, "first pts value must be set\n");
+    if (!ts_st->first_timestamp_checked && (pts == AV_NOPTS_VALUE || dts == AV_NOPTS_VALUE)) {
+        av_log(s, AV_LOG_ERROR, "first pts and dts value must be set\n");
         return AVERROR_INVALIDDATA;
     }
-    ts_st->first_pts_checked = 1;
+    ts_st->first_timestamp_checked = 1;
 
     if (st->codecpar->codec_id == AV_CODEC_ID_H264) {
         const uint8_t *p = buf, *buf_end = p + size;