avformat/mpegtsenc: Restrict "async" behavior to KLV async packets

The original code would strip off the PTS/DTS of any packets
which had a stream ID of STREAM_ID_PRIVATE_STREAM_1.  While the
intent was to apply this to asynchronous KLV packets, it was
being applied to any codec that had that same stream ID (including
types such as SMPTE 2038).

Add a clause to the if() statement to ensure it only gets applied
if the codec actually is KLV.

Signed-off-by: Devin Heitmueller <dheitmueller@ltnglobal.com>
Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/mpegtsenc.c

@@ -1455,7 +1455,8 @@ static int get_pes_stream_id(AVFormatContext *s, AVStream *st, int stream_id, in
                st->codecpar->codec_id == AV_CODEC_ID_TIMED_ID3) {
         return STREAM_ID_PRIVATE_STREAM_1;
     } else if (st->codecpar->codec_type == AVMEDIA_TYPE_DATA) {
-        if (stream_id == STREAM_ID_PRIVATE_STREAM_1) /* asynchronous KLV */
+        if (st->codecpar->codec_id == AV_CODEC_ID_SMPTE_KLV &&
+            stream_id == STREAM_ID_PRIVATE_STREAM_1) /* asynchronous KLV */
             *async = 1;
         return stream_id != -1 ? stream_id : STREAM_ID_METADATA_STREAM;
     } else {