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• A 'clean' way to cut an MP4 movie into two sections using FFMPEG ?

  30 août 2020, par Peter in Japan

  I am attempting to use FFMPEG to make a script that can easily split a short MP4 movie with sound into two pieces at a certain point. I've searched through what feels like hundreds of posts to try to find "the" answer, but most of my attempts end up with poor results, broken video files that cause my video play to freeze, and so on. I am attempting to make a script that allows me to easily cut a short anime movie (something grabbed from Twitter or some other short source) and cut it into two sections, so it can be under the 2:20 Twitter time limit, or to cut out some scene I don't want to show my followers.

  


  The issue is that FFMPEG is good at cutting videos into segments, but bad at know where keyframes are, so most videos have two seconds of blank video at the front before some keyframe appears, which looks terrible.

  


  One example I found that works well is below, which cuts any mp4 into a bunch of chunks of n second size (six seconds in the example below). Source and documentation for this is https://moe.vg/3b8eNTs

  


  ffmpeg -i seitokai.mp4 -c:v libx264 -crf 22 -map 0 -segment_time 6 -reset_timestamps 1 -g 30 -sc_threshold 0 -force_key_frames "expr:gte(t,n_forced*1)" -f segment output%03d.mp4

  


  This code works great, at least allowing me to access the "left" side of a video that I want, in this case a six-second segment I want. Can anyone tell me how to accomplish the above, but starting at the 13-second period in said video, so I could get right "right" (not starting from 00:00:00) video cut cleanly ?

  


  Alternately, a single, unified and elegant way to split (re-encode) an MP4 into two segments that forces keyframes from the very beginning of the cut pieces would be wonderful. I can't believe how hard this seems to be.

  


  Thanks in advance for any help you can give ! Greetings from rural Japan !

  


• Remove audio from specific audio track

  9 août 2024, par Ronaldo Júdice

  I have this code, and i would like to remove audio from tracks 5 and 6. I had tried everything but is not working, I can mute the audio tracks but on edition program i can see the waves, can you help me ?

  


  if (conv.format === 'mxf') {
        // Add 8 audio tracks
        ffmpeg(inputFile)
            .audioCodec('pcm_s16le') // Codec de áudio para MXF
            .outputOptions([
                '-c:v mpeg2video', // Codec de vídeo para MXF
                '-q:v 2', // Qa  vídeo
                '-map 0:v:0', 
                '-map 0:a:0', 
                '-map 0:a:0',
                '-map 0:a:0', 
                '-map 0:a:0', 
                '-map 0:a:0', // this track i want to remove the audio but keep the track
                '-map 0:a:0', //this track i want to remove the audio but keep the track
                '-map 0:a:0', 
                '-map 0:a:0', 
                '-disposition:a:0 default' // Marcar trilha 1 como padrão
            ])
            .save(outputFile)
            .on('start', commandLine => console.log(`FFmpeg comando iniciado: ${commandLine}`))
            .on('progress', progress => console.log(`Progresso: ${progress.percent}%`))
            .on('end', () => console.log(`Conversão concluída: ${outputFile}`))
            .on('error', err => console.error(`Erro na conversão de ${inputFile} para ${outputFile}: ${err.message}`));
    } else {
        // Outras conversões
        ffmpeg(inputFile)
            .outputOptions(conv.options)
            .save(outputFile)
            .on('start', commandLine => console.log(`FFmpeg comando iniciado: ${commandLine}`))
            .on('progress', progress => console.log(`Progresso: ${progress.percent}%`))
            .on('end', () => console.log(`Conversão concluída: ${outputFile}`))
            .on('error', err => console.error(`Erro na conversão de ${inputFile} para ${outputFile}: ${err.message}`));
    }


  


  I tried to use ffmpeg comands to remove audio from track.

  


• Find out what device to use for capturing with ffmpeg ?

  14 septembre 2013, par wvxvw

  I'm trying to broadcast my screen and I cannot capture audio. There's one complication however. I don't have pulseaudio, and it simply doesn't work on my system, so installing it is out of question. Below is the command I'm trying :

  ffmpeg -f alsa -i ??? -f x11grab -s 1920x1200 -r 15 -i :0.0 \
  
      -acodec pcm_s16le -vcodec libx264 \
  
      -preset fast -pix_fmt yuv420p -s 1280x800 -threads 0 -f flv "$URL"

  Here's the list of my audio devices :

  $ aplay -L
  
  null
  
      Discard all samples (playback) or generate zero samples (capture)
  
  default:CARD=PCH
  
      HDA Intel PCH, ALC269VB Analog
  
      Default Audio Device
  
  sysdefault:CARD=PCH
  
      HDA Intel PCH, ALC269VB Analog
  
      Default Audio Device
  
  front:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      Front speakers
  
  surround40:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      4.0 Surround output to Front and Rear speakers
  
  surround41:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      4.1 Surround output to Front, Rear and Subwoofer speakers
  
  surround50:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      5.0 Surround output to Front, Center and Rear speakers
  
  surround51:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      5.1 Surround output to Front, Center, Rear and Subwoofer speakers
  
  surround71:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Analog
  
      7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
  
  iec958:CARD=PCH,DEV=0
  
      HDA Intel PCH, ALC269VB Digital
  
      IEC958 (S/PDIF) Digital Audio Output
  
  hdmi:CARD=NVidia,DEV=0
  
      HDA NVidia, HDMI 0
  
      HDMI Audio Output
  
  hdmi:CARD=NVidia,DEV=1
  
      HDA NVidia, HDMI 0
  
      HDMI Audio Output
  
  hdmi:CARD=NVidia,DEV=2
  
      HDA NVidia, HDMI 0
  
      HDMI Audio Output
  
  hdmi:CARD=NVidia,DEV=3
  
      HDA NVidia, HDMI 0
  
      HDMI Audio Output

  I know that ??? should be something like hw:X,Y, but maybe it can be something else. I can't find the corresponding entry in the man page.

  As an aside, it would be great if you can suggest another audio codec. I can't find what are the options, and this particular one isn't compatible with FLV because of too high bitrate.

  PS. This is the error I'm getting :

  Could not write header for output file #0 (incorrect codec parameters ?): Invalid data found when processing input