[FFmpeg-trac] #4155(ffmpeg:new): UDP Output is Waving

FFmpeg trac at avcodec.org
Wed Dec 3 23:27:54 CET 2014

#4155: UDP Output is Waving
             Reporter:               |                     Type:  defect
  smallishzulu                       |                 Priority:  normal
               Status:  new          |                  Version:
            Component:  ffmpeg       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
 Summary of the bug (not sure if a bug):

 I use a valid TS file and use below command:
 ffmpeg -re -i test.ts -c:v copy -c:a copy -vb 2500k -minrate 2500k
 -maxrate 2500k -bufsize 5000k -muxrate 2500k -flush_packets 0 -f mpegts

 FFmpeg version is 2.4.3 (not a nightly git version)

 I traceout UDP packets using tcpdump and I see constant UDP traffic

 11:41:14.306157 IP > UDP, length 1316

 There is a Window PC in the network and using Wireshark, I can see Windows
 PC receives 1472 bytes payload. Also constant.

 I replaced Windows PC with a Linux PC and I traceout the traffic and I
 found also constant receive of UDP packets in 1316 bytes.

 However, I monitored the traffic over a Mikrotik router and I watched the
 network graphic of this UDP packets, they are waiving, not constant.

 I removed the Mikrotik router and plugged a Windows PC directly to FFmpeg
 output server and I traced network traffic using StreamXpert, I see
 traffic is waiving again.

 If I generate a UDP multicast traffic using iperf, i see constant UDP
 traffic on Mikrotik router.

 I dont know why but FFmpeg UDP multicast output is 1316 bytes but there
 maybe a problem with output timing, which I mean is output is not
 constantly 2.5Mbps

 Please see attached image file. On each run of same command, output
 graphic slightly varies/changes.

 Am I doing something wrong or is there a bug?

 (Extra note: If I pipe out same output to an ASI card instead of UDP
 stream, output Mbps is constant as well.)

Ticket URL: <https://trac.ffmpeg.org/ticket/4155>
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