[FFmpeg-user] Why latency is increase when using ffserver+ffmpeg output video stream for a long time

[Soho Soho123]

Hi All,

I use ffserver+ffmpeg to output video stream to remote VLC client.
I got the result: the latency is increase when I test it for about 3 hours.

ffserver config file :
<Stream test1-rtsp.mpg>
Feed feed1.ffm
Format rtp
VideoSize 1280x720
VideoFrameRate 30
VideoCodec libx264
NoAudio
</Stream>

ffserver command:
ffserver -f /etc/ffserver.conf &
ffmpeg command:
ffmpeg -f video4linux2 -r 30 -s 1280x720 -input_format h264 -i /dev/video1
-vcodec copy http://localhost:8090/feed1.ffm > /dev/null 2>&1 &
the url used by remote VLC client:
rtsp://192.168.1.254:5554/test1-rtsp.mpg.
=========================================================================================

After I start ffserver and then start ffmpeg, in the first 5 minutes, I
take the observation about latency between the remote client VLC and the
video source. Video source is from usb webcam.
the latency is about 1~2 seconds,
When I check the testing after about  3 hours, then the latency is about
5~6 seconds,

Does any one have idea about this problem?