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• How to insert bullet screen comments into a video by using ffmpeg ?

  7 septembre 2019, par Saeron Meng

  I would like to add some real-time comments in my video but I do not know how to use ffmpeg to realize this. The comments are like screen bullets through the screen, scrolling from right to left.

  My thought is to count the length of the comments and define speeds for them to move. Don’t worry about the source of the comments, I have already gotten them saved as an xml file. Also, I can transfer it into srt. For instance :

  <chat timestamp="671.195">
  
      <ems utctime="1562584080" sender="Bill">
  
          <richtext></richtext>
  
      </ems>
  
  </chat>
  
  <chat timestamp="677.798">
  
      <ems utctime="1562584086" sender="Jack">
  
          <richtext></richtext>
  
      </ems>
  
  </chat>

  The final result is like this (I did not find an example displayed in English), these fancy characters can move horizontally :

  

  I have searched some solutions on the Internet, most of which talk about how to write ass/srt files and add motionless subtitles. Like this :

  3
  
  00:00:39,770 --> 00:00:41,880
  
  When I was lying there in the VA hospital ...
  
  
  
  4
  
  00:00:42,550 --> 00:00:44,690
  
  ... with a big hole blown through the middle of my life,
  
  
  
  5
  
  00:00:45,590 --> 00:00:48,120
  
  ... I started having these dreams of flying.

  ffmpeg -i infile.mp4 -i infile.srt -c copy -c:s mov_text outfile.mp4

  But I need another kind of "subtitles" which can move.

  So my question is, how to modify the ffmpeg command and the template of srt file so as to arrange the subtitles from the top to the bottom and let them move from right to left ?

• Transcoding from VP8 to H264 is not working using fluent-ffmpeg library using node.js

  3 septembre 2019, par Mihir Patel

  I have tried transcoding stream from VP8 to H264 using command line it’s working fine but when I tried the same thing using fluent-ffmpeg it is not working as expected.

  Version information

  fluent-ffmpeg version : "2.1.2"

  ffmpeg version : "3.4.4-1 16.04.york0"

  OS : "Ubuntu"

  Trasncoding from VP8 to H264 is working using command

  ffmpeg -analyzeduration 300M -probesize 300M -protocol_whitelist file,udp,rtp -i portal-vp8.sdp -c:v libx264 -profile:v high -level:v 3.2 -pix_fmt yuv420p -x264-params keyint=25:scenecut=0 -r 25 -c:a aac -ar 16k -ac 1 -preset ultrafast -tune zerolatency -f flv rtmp://my-server-ip/myapp/testvp8

  My sdp is

  v=0
  
  o=- 0 0 IN IP4 127.0.0.1
  
  s=No Name
  
  c=IN IP4 127.0.0.1
  
  t=0 0
  
  a=tool:libavformat 55.2.100
  
  m=audio 5396 TCP 111
  
  a=rtpmap:111 opus/48000
  
  m=video 5398 RTP/AVP 100
  
  a=rtpmap:100 VP8/90000
  
  a=fmtp:100 packetization-mode=1

  Trasncoding from VP8 to H264 is not working using library

  var sdpString = "v=0\r\no=- 0 0 IN IP4 127.0.0.1\r\ns=No Name\r\nc=IN IP4 127.0.0.1\r\nt=0 0\r\na=tool:libavformat 55.2.100\r\nm=audio 5120 TCP 111\r\na=rtpmap:111 opus/48000\r\nm=video 5122 RTP/AVP 100\r\na=rtpmap:100 VP8/90000";
  
  
  
  let sdp = stringToStream(sdpString);
  
  var inputOptions = [];
  
      inputOptions.push('-analyzeduration');
  
      inputOptions.push('300M');
  
      inputOptions.push('-probesize');
  
      inputOptions.push('300M');
  
      inputOptions.push('-protocol_whitelist');
  
      inputOptions.push('file,udp,rtp,pipe');
  
  
  
  var outputOptions = [];
  
      outputOptions.push('-c:v');
  
      outputOptions.push('libx264');
  
  
  
      outputOptions.push('-profile:v');
  
      outputOptions.push('high');
  
  
  
      outputOptions.push('-level:v');
  
      outputOptions.push('3.2');
  
  
  
      outputOptions.push('-pix_fmt');
  
      outputOptions.push('yuv420p');
  
  
  
      outputOptions.push('-x264-params');
  
      outputOptions.push('keyint=25:scenecut=0');
  
  
  
      outputOptions.push('-r');
  
      outputOptions.push('25');
  
  
  
      outputOptions.push('-c:a');
  
      outputOptions.push('aac');
  
  
  
      outputOptions.push('-ar');
  
      outputOptions.push('16k');
  
  
  
      outputOptions.push('-ac');
  
      outputOptions.push('1');
  
  
  
      outputOptions.push('-preset');
  
      outputOptions.push('ultrafast');
  
  
  
      outputOptions.push('-tune');
  
      outputOptions.push('zerolatency');
  
  
  
      outputOptions.push('-f');
  
      outputOptions.push('flv');
  
  
  
  var outputUrl = "rtmp://my-server-ip/myapp/testvp8";
  
  
  
  var command = FfmpegCommand(sdp).inputOptions(inputOptions).outputOptions(outputOptions).output(outputUrl)
  
          .on('start', function (commandLine) {
  
              console.log('Spawned Ffmpeg with command: ' + commandLine);
  
          })
  
          .on('stderr', function(stderrLine) {
  
              console.log('FFMPEG Stderr output: ' + stderrLine);
  
          });
  
  
  
      command.run();
  
  });

  Produced command using library

  ffmpeg -analyzeduration 300M -probesize 300M -protocol_whitelist file,udp,rtp,pipe -i pipe:0 -c:v libx264 -profile:v high -level:v 3.2 -pix_fmt yuv420p -x264-params keyint=25:scenecut=0 -r 25 -c:a aac -ar 16k -ac 1 -preset ultrafast -tune zerolatency -f flv rtmp://my-server-ip/myapp/testvp8

  FFmpeg logs

  FFMPEG Stderr output: ffmpeg version 3.4.4-1~16.04.york0 Copyright (c) 2000-2018 the FFmpeg developers
  
  FFMPEG Stderr output:   built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
  
  FFMPEG Stderr output:   configuration: --prefix=/usr --extra-version='1~16.04.york0' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  
  FFMPEG Stderr output:   libavutil      55. 78.100 / 55. 78.100
  
  FFMPEG Stderr output:   libavcodec     57.107.100 / 57.107.100
  
  FFMPEG Stderr output:   libavformat    57. 83.100 / 57. 83.100
  
  FFMPEG Stderr output:   libavdevice    57. 10.100 / 57. 10.100
  
  FFMPEG Stderr output:   libavfilter     6.107.100 /  6.107.100
  
  FFMPEG Stderr output:   libavresample   3.  7.  0 /  3.  7.  0
  
  FFMPEG Stderr output:   libswscale      4.  8.100 /  4.  8.100
  
  FFMPEG Stderr output:   libswresample   2.  9.100 /  2.  9.100
  
  FFMPEG Stderr output:   libpostproc    54.  7.100 / 54.  7.100
  
  FFMPEG Stderr output: [sdp @ 0x55c28151c180] max delay reached. need to consume packet
  
  FFMPEG Stderr output: [sdp @ 0x55c28151c180] RTP: missed 1 packets

  Observed results

  I have observed that inputted VP8 stream is not transcoded to H264 using FFmpeg library

  Expected results

  Inputted VP8 stream should be transcoded to H264 using the library.

  Please help so how can I resolve the issue.

• Dynamic subtitles by ffmpeg

  8 septembre 2019, par Saeron Meng

  I would like to add some commentary texts into my video but I do not know how to use ffmpeg to realize this. The comments are like screen bullets through the screen, appearing in the right margin, moving and scrolling, and disappearing from the left.

  My thought is to count the length of the comments and define speeds for them to move and I have already gotten the comments saved as an xml file. But even though I can transfer it into srt file, the tricky problem is, it is hard to write the speeds of the subtitles, or something like that, in an srt file, and apply them to ffmpeg commands or APIs. Here is an example of comments (xml file) :

  <chat timestamp="671.195">
  
      <ems utctime="1562584080" sender="Bill">
  
          <richtext></richtext>
  
      </ems>
  
  </chat>
  
  <chat timestamp="677.798">
  
      <ems utctime="1562584086" sender="Jack">
  
          <richtext></richtext>
  
      </ems>
  
  </chat>

  The final result is like this (I did not find an example in websites in English. In China, such moving subtitles are called "danmu" or "screen bullets"), these colorful characters can move horizontally from right to left :

  

  1. I have searched some solutions on the Internet, most of which talk about how to write ass/srt files and add motionless subtitles. Like this :

  ffmpeg -i infile.mp4 -i infile.srt -c copy -c:s mov_text outfile.mp4

  3
  
  00:00:39,770 --> 00:00:41,880
  
  When I was lying there in the VA hospital ...
  
  
  
  4
  
  00:00:42,550 --> 00:00:44,690
  
  ... with a big hole blown through the middle of my life,
  
  
  
  5
  
  00:00:45,590 --> 00:00:48,120
  
  ... I started having these dreams of flying.

  But I need another kind of "subtitles" which can move.

  2. When it comes to scrolling subtitles, there are still some solutions : Scrolling from RIGHT to LEFT in ffmpeg / drawtext

  So my question is, how to combine the solutions above to arrange subtitles from top to bottom and let them move concerning the timestamps of the comments ?