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• ffmpeg to ffserver works, but cannot view

  13 avril 2017, par nix

  I have a generic windows webcam that I am trying to broadcast

  ffmpeg -f vfwcap -I 0 -vcodedc libx264 -tune zerolatency-b 900k -f mpegts udp://domain.com:8090

  which appears error free.
  I can see plenty of traffic using tcpdump on port 8090

  ffserver is configure on a FreeBSD server with no firewall configured

  # cat /usr/local/etc/ffserver.conf| egrep -v "(^#.*|^$)"
  
  HTTPPort 8090
  
  HTTPBindAddress 0.0.0.0
  
  MaxHTTPConnections 2000
  
  MaxClients 1000
  
  MaxBandwidth 1000
  
  CustomLog -
  
  <feed>
  
  File /tmp/feed1.ffm
  
  FileMaxSize 200K
  
  ACL allow 98.124.117.129
  
  </feed>
  
  <stream>
  
  Feed feed1.ffm
  
  Format mpeg
  
  AudioBitRate 32
  
  AudioChannels 1
  
  AudioSampleRate 44100
  
  VideoBitRate 64
  
  VideoBufferSize 40
  
  VideoFrameRate 3
  
  VideoSize 160x128
  
  VideoGopSize 12
  
  ACL ALLOW all
  
  </stream>
  
  <stream>
  
  Feed feed1.ffm
  
  Format asf
  
  VideoFrameRate 15
  
  VideoSize 352x240
  
  VideoBitRate 256
  
  VideoBufferSize 40
  
  VideoGopSize 30
  
  AudioBitRate 64
  
  StartSendOnKey
  
  </stream>
  
  <stream>
  
  Format rtp
  
  File "/tmp/feed1.ffm"
  
  </stream>
  
  <stream>
  
  Format status
  
  ACL allow localhost
  
  ACL allow 192.168.0.0 192.168.255.255 98.124.117.129 0.0.0.0
  
  </stream>
  
  <redirect>
  
  URL http://www.ffmpeg.org/
  
  </redirect>

  The port is live

  # netstat -an|grep 8090
  
  tcp4       0      0 *.8090                 *.*                    LISTEN

  But when I try to connect via VLC to the ffserver

  rtsp://persiaspalace.us:8090/feed1.ffm

  connection fails.
  There are no networking issues

  How do I configure a webcam broadcast from ffmpeg to ffserver for viewing via VLC (or similar) ?

• FFmpeg accurate speed for x11grab

  21 mars 2017, par Peter Shaw

  Hi I am trying to make a screencast in realtime with ffmpeg on Linux.

  This is my call :

  ffmpeg \
  
  -f x11grab \
  
  -s 1920x1080 \
  
  -r 24 -framerate 24 \
  
  -i $DISPLAY \
  
  -preset ultrafast \
  
  -tune zerolatency \
  
  -pix_fmt yuv420p \
  
  -acodec copy \
  
  -vcodec libx264 \
  
  -b:v 500k \
  
  -crf 0 \
  
  -threads 0 \
  
  -y /data/production/out.mkv \
  
  -an \
  
  -t $LEN

  As far as i can tell this is near accurate and has a decent quality. Maybe there is a better settling, than let me please know.

  As the screen will be captured the timing is not correct. I get a message with something like this :

  frame=  901 fps= 22 q=0.0 size=   66553kB time=00:00:37.50 bitrate=14538.3kbits/s speed=0.905x   

  The Speed will turn around from 0.600x to 1.200x and is never stable to 1x.
  I wonder if it’s possible to get a accurate timing.
  I have to do a 60sec movie that is in speed exactly 100% like the frame-buffer is. Is it possible ?

• very low latency streaminig with ffmpeg using a webcam

  22 mars 2017, par userDtrm

  I’m trying to configure ffmpeg to do a real-time video streaming using a webcam. The ffmpeg encoder command I use is as follows.

  ffmpeg -f v4l2 -input_format yuyv422 -s 640x480 -i /dev/video0 -c:v libx264 -profile:v baseline -trellis 0 -subq 1 -level 32 -preset superfast -tune zerolatency -me_method epzs -crf 30 -threads 0 -bufsize 1 -refs 4 -coder 0 -b_strategy 0 -bf 0 -sc_threshold 0 -x264-params vbv-maxrate=2000:slice-max-size=1500:keyint=30:min-keyint=10: -pix_fmt yuv420p -an -f mpegts udp://192.168.1.8:5001

  The ffplay command used to display the video feed is,

  ffplay -analyzeduration 1 -fflags -nobuffer -i udp://192.168.1.8:5001

  However, I’m experiencing a latency of 0.5 - 1.0s latency in the video stream. Is there a way to reduce this to a number less than 100ms. Also, when I replace the v4l2 camera capture with a screen capture using x11grab, the stream is almost real-time and I experience no noticeable delays. Moreover, changing the encoder from x264 to mpeg2 had no effect on the latency. In addition, the statistics from the ffmpeg shows that the encoder is performing at a 30fps rate, which I believe indicates that the encoding is real-time. This leaves me with only one reason for the experienced delay.

  • Is there a significant delay in buffers when using v4l2 during video capturing in a webcam ?
  • I don’t think the transmission delay is in effect in this case as I see no latencies when screen capture is used under the same conditions.
  • Can this latency be further reduced ?. Can someone think of a different encoder configuration to be used instead of the one that I’ve been using ?.

  Any suggestions or assistance is highly appreciated.

  Thank You.