VC1testenc: convert pts values to correct time-base.

VC1 test container always uses time-base 1 ms, so we must convert
from whatever time-base the application gave us to that, otherwise
the video will play at ridiculous speeds.
It would be possible to signal that a container supports only one
time-base and have code in a layer above do the conversion, but
for a single format this seems over-engineered.

libavformat/vc1testenc.c

@@ -55,11 +55,14 @@ static int vc1test_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
     RCVContext *ctx = s->priv_data;
     ByteIOContext *pb = s->pb;
+    uint32_t pts = av_rescale(pkt->pts,
+                              1000 * (uint64_t)s->streams[0]->time_base.num,
+                              s->streams[0]->time_base.den);
 
     if (!pkt->size)
         return 0;
     put_le32(pb, pkt->size | ((pkt->flags & AV_PKT_FLAG_KEY) ? 0x80000000 : 0));
-    put_le32(pb, pkt->pts);
+    put_le32(pb, pts);
     put_buffer(pb, pkt->data, pkt->size);
     put_flush_packet(pb);
     ctx->frames++;