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• ffmpeg udp capture not working

  27 février 2017, par user3172852

  I have confirmed that there is incoming UDP packets at port 5968 of my computer with wireshark.
  However when I try to capture these packets with ffmpeg. After exiting (ctrl+c) I get no output, the output file is not even written to disk. This is what my terminal looks like.

  ubuntu@ip-132-31-40-100:~$ ffmpeg -i udp://127.0.0.1:59618 -vcodec copy stream.mp4
  
      ffmpeg version git-2017-01-22-f1214ad Copyright (c) 2000-2017 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 --enable-libwavpack --enable-nvenc
  
        libavutil      55. 44.100 / 55. 44.100
  
        libavcodec     57. 75.100 / 57. 75.100
  
        libavformat    57. 63.100 / 57. 63.100
  
        libavdevice    57.  2.100 / 57.  2.100
  
        libavfilter     6. 69.100 /  6. 69.100
  
        libavresample   3.  2.  0 /  3.  2.  0
  
        libswscale      4.  3.101 /  4.  3.101
  
        libswresample   2.  4.100 /  2.  4.100
  
        libpostproc    54.  2.100 / 54.  2.100

• ffmpeg copy stream preserving FPS

  10 mars 2017, par James Taylor

  I have a stream that I know is outputting at a certain frame rate (30 FPS). I want to use ffmpeg to make a copy of this stream and save it to disk.

  I have the following command :

  ffmpeg -i http://input/ -c copy -map 0 \
  
      -f segment -strftime 1 -segment_time 900 \
  
      -segment_atclocktime 1 -segment_format mp4 %Y-%m-%d_%H-%M-%S.mp4

  But when I run the command, I see the following :

  frame=   32 fps=3.9 q=-1.0 Lsize=N/A time=00:00:01.27 bitrate=N/A

  Where it appears the FPS is hovers around 4.0 FPS and time moves slower than real time.

  I tried added -re (copy the rate of the input stream) and -r 30 (manually set the rate to 30 FPS) flag specified before the input file, but it didn’t seem to work.

  I also read a similar question here using -framerate 30, but that option doesn’t exist in the man pages and is an Invalid option.

  Any help would be greatly appreciated !

  ---

  So I let the modified command (removing the flags -c copy -map 0) run for exactly 5 minutes. Running ffprobe yields :

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '2017-03-10_01-09-12.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf57.2.100
  
    Duration: 00:00:15.43, start: 0.066016, bitrate: 13416 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc), 1024x768, 13414 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler

  Again, this only produces 15 seconds of video and I can’t seem to get a 1:1 relationship between the input stream of 30 FPS and an output stream also in 30 FPS in real time. Playing the video yields something that’s sped up.

• Convert Byte-range to Time-range in html

  15 mars 2017, par fengshaun

  I have some sever-side code that currently supports the http byte range requests without an issue. However, I want to be able to transcode the video file (which is located on-disk) on-the-fly with ffmpeg before I send the transcoded chunk to the client, but ffmpeg requires I give it a seek time whereas I get byte ranges from the client. How would I be able to figure out the time range (seek time) of a video file given the byte range from the client browser ?

  I have already looked at this question which assumes the server already knows the specified time.

  I am open to using an html5 video player which supports the use of time ranges to request data instead of byte ranges, but I have been unable to find an implementation or figure out how the javascript side of buffering <video></video> works.