ffmpeg -v debug -analyzeduration 0 -i http://localhost:8080/ffmpeg/img%03d.png -c:v libx264 -vf "fps=25,format=yuv420p" out.mp4
ffmpeg version N-80901-gfebc862 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab
  libavutil      55. 28.100 / 55. 28.100
  libavcodec     57. 48.101 / 57. 48.101
  libavformat    57. 41.100 / 57. 41.100
  libavdevice    57.  0.102 / 57.  0.102
  libavfilter     6. 47.100 /  6. 47.100
  libavresample   3.  0.  0 /  3.  0.  0
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  1.100 /  2.  1.100
  libpostproc    54.  0.100 / 54.  0.100
Splitting the commandline.
Reading option '-v' ... matched as option 'v' (set logging level) with argument 'debug'.
Reading option '-analyzeduration' ... matched as AVOption 'analyzeduration' with argument '0'.
Reading option '-i' ... matched as input file with argument 'http://localhost:8080/ffmpeg/img%03d.png'.
Reading option '-c:v' ... matched as option 'c' (codec name) with argument 'libx264'.
Reading option '-vf' ... matched as option 'vf' (set video filters) with argument 'fps=25,format=yuv420p'.
Reading option 'out.mp4' ... matched as output file.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option v (set logging level) with argument debug.
Successfully parsed a group of options.
Parsing a group of options: input file http://localhost:8080/ffmpeg/img%03d.png.
Successfully parsed a group of options.
Opening an input file: http://localhost:8080/ffmpeg/img%03d.png.
[http @ 0x39e94c0] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39e94c0] request: GET /ffmpeg/img000.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ea920] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ea920] request: GET /ffmpeg/img001.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ea920] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ea920] request: GET /ffmpeg/img002.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ea920] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ea920] request: GET /ffmpeg/img004.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ec5e0] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ec5e0] request: GET /ffmpeg/img008.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ea920] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ea920] request: GET /ffmpeg/img016.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ec5e0] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ec5e0] request: GET /ffmpeg/img032.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ea920] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ea920] request: GET /ffmpeg/img064.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ec5e0] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ec5e0] request: GET /ffmpeg/img128.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ea920] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ea920] request: GET /ffmpeg/img256.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ec5e0] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ec5e0] request: GET /ffmpeg/img512.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ea920] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ea920] request: GET /ffmpeg/img1024.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ea920] HTTP error 404 Not Found
[http @ 0x39ec5e0] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ec5e0] request: GET /ffmpeg/img513.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ec5e0] HTTP error 404 Not Found
[http @ 0x39ec020] Setting default whitelist 'http,https,tls,rtp,tcp,udp,crypto,httpproxy'
[http @ 0x39ec020] request: GET /ffmpeg/img000.png HTTP/1.1
User-Agent: Lavf/57.41.100
Accept: */*
Range: bytes=0-
Connection: close
Host: localhost:8080
Icy-MetaData: 1


[http @ 0x39ec020] HTTP error 404 Not Found
[image2 @ 0x39e8d60] Could not open file : http://localhost:8080/ffmpeg/img000.png
[image2 @ 0x39e8d60] Could not find codec parameters for stream 0 (Video: png, 1 reference frame, none(pc)): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, image2, from 'http://localhost:8080/ffmpeg/img%03d.png':
  Duration: 00:00:20.52, start: 0.000000, bitrate: N/A
    Stream #0:0, 0, 1/25: Video: png, 1 reference frame, none(pc), 25 tbr, 25 tbn, 25 tbc
Successfully opened the file.
Parsing a group of options: output file out.mp4.
Applying option c:v (codec name) with argument libx264.
Applying option vf (set video filters) with argument fps=25,format=yuv420p.
Successfully parsed a group of options.
Opening an output file: out.mp4.
Output #0, mp4, to 'out.mp4':
Output file #0 does not contain any stream