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• Use ffmpeg to create a video/audio file of X length, and then add audio/video sequences from multiple other files

  9 novembre 2015, par robert paré

  I have several mp4 files that contain video and audio content ("base" videos)

  I have a length value (recordingLength) in which the output video should be (let’s say 3600 seconds).

  I have to take clips from the "base" videos, at specific times and of specific duration.

  What I’m trying, is first creating a blank file with the total length (recordingLength) of 3600 seconds. I do it like so :

  ffmpeg -f lavfi -i anullsrc -t 3600 -c:a libfdk_aac ./output.mp4

  Then let’s say I have 5 base videos each lasting a couple of minutes, and I need to take a short segment from each of them (20-30 seconds) at a specific time, and then merge that segment at a specific time in the blank file created above. I tried playing around with -itsoffset {seconds} -t {seconds} but I’m still really just playing around trying to get my head around all the options.

• need help using ffmpeg to "concat" multiple audio files (webm, mp4) to make one longer MP3 of audio

  28 septembre 2020, par djturbojp7

  I have done some searching (for several hours) and tried to manipulate many examples to work for me, but I still keep coming up empty here.

  


  I am using linux-mint 19, with ffmpeg installed. I have a folder with several audio files. The majority of these are "webm" (with no video) and there are a few "m4a". I am trying to make one long mp3 file from the audio in all of these strung together from start to finish.

  


  Lets say for sake of argument, my directory has the following files :

  


  audio file a.webm
audio file b.webm
audio file c.m4a
audio file d.webm


  


  I found a script that I could write online where someone is creating a file called "mylist.txt" with this bit of code :

  


      # with a bash for loop
for f in ./*.*; do echo "file '$f'" >> mylist.txt; done
# or with printf
printf "file '%s'\n" ./*.* > mylist.txt


  


  this generated a text file with the following type of content :

  


  file './audio file a.webm'
file './audio file b.webm'
file './audio file c.m4a'
file './audio file d.webm'


  


  first, I believe the "./" is causing a problem, because when I look at other examples I don't see this but I am not sure why it is generating this way in my script because I don't see this in web examples online. Second, I have tried to "concate" this with ffmpeg but I'm not sure which is the best option. I found some documentation here :

  


  https://trac.ffmpeg.org/wiki/Concatenate

  


  however this example applies to video specifically

  


  Can anyone lead me in the right direction ?

  


  EDIT******

  


  I tried the solution below, with "mylist.txt" as the input and I am getting an error :

  


      user@machine/TEMP$ ffmpeg -i mylist.txt -filter_complex "[0:a][1:a][2:a][3:a]concat=n=20:a=1:v=0[a]" -map "[a]" output.mp3
ffmpeg version 4.2.4-1ubuntu0.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
  configuration: --prefix=/usr --extra-version=1ubuntu0.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, tty, from 'mylist.txt':
  Duration: 00:00:00.40, bitrate: 47 kb/s
    Stream #0:0: Video: ansi, pal8, 640x400, 25 fps, 25 tbr, 25 tbn, 25 tbc
Stream specifier ':a' in filtergraph description [0:a][1:a][2:a][3:a]concat=n=20:a=1:v=0[a] matches no streams.


  


• Crash in audio resampler with some audio rates - FFMPEG PHP [migrated]

  4 octobre 2012, par Olaf Erlandsen

  i have a problem with this command( FFMPEG PHP ) :

  Command :

  ffmpeg -i 62f76f050494f0ed6a5997967c00c0c0.wmv -ss 0 -t 99 -y -ar 44100 -async 44100 -r 29.970 -ac 2 -qscale 5 -f flv 62f76f050494f0ed6a5997967c00c0c0.flv

  Output :

  FFmpeg version 0.6.5, Copyright (c) 2000-2010 the FFmpeg developers
  
    built on Jan 29 2012 17:52:15 with gcc 4.4.5 20110214 (Red Hat 4.4.5-6)
  
    configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man --incdir=/usr/include --disable-avisynth --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC' --enable-avfilter --enable-avfilter-lavf --enable-libdc1394 --enable-libdirac --enable-libfaac --enable-libfaad --enable-libfaadbin --enable-libgsm --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libx264 --enable-gpl --enable-nonfree --enable-postproc --enable-pthreads --enable-shared --enable-swscale --enable-vdpau --enable-version3 --enable-x11grab
  
    libavutil     50.15. 1 / 50.15. 1
  
    libavcodec    52.72. 2 / 52.72. 2
  
    libavformat   52.64. 2 / 52.64. 2
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libavfilter    1.19. 0 /  1.19. 0
  
    libswscale     0.11. 0 /  0.11. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  [asf @ 0xe81670]max_analyze_duration reached
  
  Input #0, asf, from '/var/www/resources/tmp/62f76f050494f0ed6a5997967c00c0c0.wmv':
  
    Metadata:
  
      WMFSDKVersion   : 12.0.7601.17514
  
      WMFSDKNeeded    : 0.0.0.0000
  
      IsVBR           : 0
  
    Duration: 00:00:50.87, bitrate: 2467 kb/s
  
      Stream #0.0: Audio: wmapro, 44100 Hz, stereo, flt, 256 kb/s
  
      Stream #0.1: Video: vc1, yuv420p, 950x460 [PAR 1:1 DAR 95:46], 25 fps, 25 tbr, 1k tbn, 25 tbc
  
  Output #0, flv, to '/var/www/resources/media/62f76f050494f0ed6a5997967c00c0c0.flv':
  
    Metadata:
  
      encoder         : Lavf52.64.2
  
      Stream #0.0: Video: flv, yuv420p, 950x460 [PAR 1:1 DAR 95:46], q=2-31, 200 kb/s, 1k tbn, 29.97 tbc
  
      Stream #0.1: Audio: libmp3lame, 11025 Hz, stereo, s16, 64 kb/s
  
  Stream mapping:
  
    Stream #0.1 -> #0.0
  
    Stream #0.0 -> #0.1
  
  Press [q] to stop encoding
  
  frame=   72 fps=  0 q=5.0 size=       0kB time=10.91 bitrate=   0.0kbits/s    
  
  Multiple frames in a packet from stream 0
  
  Warning, using s16 intermediate sample format for resampling
  
  frame=  141 fps=139 q=5.0 size=     103kB time=8.15 bitrate= 103.2kbits/s    
  
  frame=  220 fps=144 q=5.0 size=     875kB time=10.92 bitrate= 656.6kbits/s    
  
  frame=  290 fps=143 q=5.0 size=    1525kB time=13.74 bitrate= 909.1kbits/s    
  
  frame=  356 fps=141 q=5.0 size=    2153kB time=15.99 bitrate=1103.1kbits/s    
  
  frame=  427 fps=141 q=5.0 size=    2847kB time=18.70 bitrate=1247.0kbits/s    
  
  frame=  497 fps=141 q=5.0 size=    3771kB time=21.16 bitrate=1460.0kbits/s    
  
  frame=  575 fps=142 q=5.0 size=    4695kB time=24.61 bitrate=1563.0kbits/s    
  
  frame=  639 fps=141 q=5.0 size=    5301kB time=26.80 bitrate=1620.2kbits/s    
  
  frame=  703 fps=139 q=5.0 size=    5829kB time=29.36 bitrate=1626.2kbits/s    
  
  frame=  774 fps=139 q=5.0 size=    6659kB time=32.39 bitrate=1684.0kbits/s    
  
  frame=  842 fps=139 q=5.0 size=    7915kB time=35.27 bitrate=1838.6kbits/s    
  
  frame=  911 fps=139 q=5.0 size=    9011kB time=37.98 bitrate=1943.4kbits/s    
  
  frame=  975 fps=138 q=5.0 size=    9788kB time=40.59 bitrate=1975.3kbits/s    
  
  frame= 1041 fps=138 q=5.0 size=   10904kB time=43.83 bitrate=2037.9kbits/s    
  
  frame= 1115 fps=138 q=5.0 size=   11795kB time=46.24 bitrate=2089.8kbits/s    
  
  frame= 1183 fps=138 q=5.0 size=   12678kB time=48.74 bitrate=2130.7kbits/s    
  
  frame= 1247 fps=137 q=5.0 size=   13964kB time=51.36 bitrate=2227.5kbits/s    
  
  frame= 1271 fps=136 q=5.0 Lsize=   15865kB time=58.86 bitrate=2208.1kbits/s
  
  video:15366kB audio:462kB global headers:0kB muxing overhead 0.238956%

  Problem :

  Warning, using s16 intermediate sample format for resampling

  I've also tried changing the parameter

  From

  -ar 44100

  to

  -ar 11025

  Thanks !