[FFmpeg-user] Can't make zmq listen on anything but port 5555

[Thomas Seilund]

Hi All

I have an ex where ffmpeg using zmq listens on port 5555. Command is 
only used to demonstrate opening of local port:

ffmpeg -y -video_size 320x240 -i /dev/video0 -filter_complex 
"zmq,setpts=PTS-STARTPTS" -c:v libx264 -s 320x240 -r 25 -f mpegts /dev/null
ffmpeg version N-105723-gfee804f7ed Copyright (c) 2000-2022 the FFmpeg 
developers
   built with gcc 10 (Debian 10.2.1-6)
   configuration: --prefix=/home/pi/ffmpeg_build 
--extra-cflags=-I/home/pi/ffmpeg_build/include 
--extra-ldflags=-L/home/pi/ffmpeg_build/lib --extra-libs='-lpthread -lm' 
--ld=g++ --bindir=/home/pi/bin --enable-gpl --enable-gnutls 
--enable-libfdk-aac --enable-libfreetype --enable-libx264 
--enable-libzmq --enable-nonfree
   libavutil      57. 21.100 / 57. 21.100
   libavcodec     59. 21.100 / 59. 21.100
   libavformat    59. 17.102 / 59. 17.102
   libavdevice    59.  5.100 / 59.  5.100
   libavfilter     8. 27.100 /  8. 27.100
   libswscale      6.  5.100 /  6.  5.100
   libswresample   4.  4.100 /  4.  4.100
   libpostproc    56.  4.100 / 56.  4.100
Input #0, video4linux2,v4l2, from '/dev/video0':
   Duration: N/A, start: 2132.759891, bitrate: 36864 kb/s
   Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 320x240, 
36864 kb/s, 30 fps, 30 tbr, 1000k tbn
Stream mapping:
   Stream #0:0 (rawvideo) -> zmq:default
   setpts:default -> Stream #0:0 (libx264)
Press [q] to stop, [?] for help
[libx264 @ 0x55a2375520] using cpu capabilities: ARMv8 NEON
[libx264 @ 0x55a2375520] profile High 4:2:2, level 1.3, 4:2:2, 8-bit
Output #0, mpegts, to '/dev/null':
   Metadata:
     encoder         : Lavf59.17.102
   Stream #0:0: Video: h264, yuv422p(tv, progressive), 320x240, q=2-31, 
25 fps, 90k tbn
     Metadata:
       encoder         : Lavc59.21.100 libx264
     Side data:
       cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame=  348 fps= 15 q=-1.0 Lsize=     407kB time=00:00:23.00 bitrate= 
144.8kbits/s speed=0.985x
video:289kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB 
muxing overhead: 40.876137%
[libx264 @ 0x55a2375520] frame I:2     Avg QP:20.36  size: 17342
[libx264 @ 0x55a2375520] frame P:88    Avg QP:21.29  size:  2500


I confirm that port 5555 is open using nmap:

nmap 127.0.0.1
Starting Nmap 7.80 ( https://nmap.org ) at 2022-03-08 21:39 CET
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00039s latency).
Not shown: 997 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
631/tcp  open  ipp
5555/tcp open  freeciv


I want to run two instances of ffmpeg both using zmq. I guess they have 
to use separate ports. So I try this to use port 5565. Again, command is 
only used to demonstrate opening of local port:

ffmpeg -y -video_size 320x240 -i /dev/video0 -filter_complex 
"zmq=bind_address=tcp\\\://127.0.0.1\\\:5565,setpts=PTS-STARTPTS" -c:v 
libx264 -s 320x240 -r 25 -f mpegts /dev/null
ffmpeg version N-105723-gfee804f7ed Copyright (c) 2000-2022 the FFmpeg 
developers
   built with gcc 10 (Debian 10.2.1-6)
   configuration: --prefix=/home/pi/ffmpeg_build 
--extra-cflags=-I/home/pi/ffmpeg_build/include 
--extra-ldflags=-L/home/pi/ffmpeg_build/lib --extra-libs='-lpthread -lm' 
--ld=g++ --bindir=/home/pi/bin --enable-gpl --enable-gnutls 
--enable-libfdk-aac --enable-libfreetype --enable-libx264 
--enable-libzmq --enable-nonfree
   libavutil      57. 21.100 / 57. 21.100
   libavcodec     59. 21.100 / 59. 21.100
   libavformat    59. 17.102 / 59. 17.102
   libavdevice    59.  5.100 / 59.  5.100
   libavfilter     8. 27.100 /  8. 27.100
   libswscale      6.  5.100 /  6.  5.100
   libswresample   4.  4.100 /  4.  4.100
   libpostproc    56.  4.100 / 56.  4.100
Input #0, video4linux2,v4l2, from '/dev/video0':
   Duration: N/A, start: 2210.905629, bitrate: 36864 kb/s
   Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 320x240, 
36864 kb/s, 30 fps, 30 tbr, 1000k tbn
Stream mapping:
   Stream #0:0 (rawvideo) -> zmq:default
   setpts:default -> Stream #0:0 (libx264)
Press [q] to stop, [?] for help
[libx264 @ 0x5598bae610] using cpu capabilities: ARMv8 NEON
[libx264 @ 0x5598bae610] profile High 4:2:2, level 1.3, 4:2:2, 8-bit
Output #0, mpegts, to '/dev/null':
   Metadata:
     encoder         : Lavf59.17.102
   Stream #0:0: Video: h264, yuv422p(tv, progressive), 320x240, q=2-31, 
25 fps, 90k tbn
     Metadata:
       encoder         : Lavc59.21.100 libx264
     Side data:
       cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
^CError writing trailer of /dev/null: Immediate exit requestedtrate= 
177.0kbits/s speed=0.505x
frame=  107 fps= 15 q=-1.0 Lsize=     128kB time=00:00:06.88 bitrate= 
152.6kbits/s speed=0.944x
video:92kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB 
muxing overhead: 39.860378%
Error closing file /dev/null: Immediate exit requested
[libx264 @ 0x5598bae610] frame I:1     Avg QP:21.56  size: 14075


To my supprise port 5565 is not opened. I confirm that using nmap:

nmap 127.0.0.1
Starting Nmap 7.80 ( https://nmap.org ) at 2022-03-08 21:38 CET
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00041s latency).
Not shown: 998 closed ports
PORT    STATE SERVICE
22/tcp  open  ssh
631/tcp open  ipp


What am I doing wrong?

Thanks in advance

Thomas S