Here is my ffserver.conf.

Port 9090
MaxHTTPConnections 2000
MaxClients 1000
MaxBandwidth 1000
CustomLog -
NoDaemon

<Feed feed1.ffm>
File /tmp/feed1.ffm
FileMaxSize 200K
</Feed>

<Stream test1.mpg>
Feed feed1.ffm
Format mpeg
</Stream>

I am getting a input stream of mjpeg (multipart jpeg at approx 3 frames per second)which I pipe to ffmpeg with below command.
./getJpgStream | ffmpeg -f image2 mjpeg -i - http://localhost:9090/feed1.ffm

Input #0, mjpeg, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj444p(pc, bt470bg), 320x557, 25 tbr, 1200k tbn, 25 tbc
Missing audio stream which is required by this ffm

It fails with mission audio error. Any ideas how to resolve this?