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• How to determine which offsets changed in MP4 file after cutting a part of the MP4 file

  16 février 2021, par Muath

  This image displays each offset and the role of that offset in mp4 file.

  


  

  


  And this is MP4 file viewed in Hex-Editor :

  


  

  


  When cutting (as an example) first 60 seconds of that video or doing any cutting process, How can I know which offsets has been changed ?

  


• FFMPEG : Fill/Change (part of) audio waveform color as per actual progress with respect to time progress

  13 août 2018, par Software Development Consultan

  I am trying to make command which is generating waveform from mp3 file and show on background image and play audio.
  Togethr with this, I want to change waveform color left to right (something like progressbar) as per overall video time elapses.

  I have created following command which shows progress bar using drawbox to fill box color as per current time position.

  ffmpeg -y -loop 1 -threads 0 -i sample_background.png -i input.mp3 -filter_complex "color=red@0.5:s=1280x100[Color] ;[0:v]drawbox=0:155:1280:100:gray@1:t=fill[baserect] ;[1:a]aformat=channel_layouts=mono,showwaves=s=1280x100:rate=7:mode=cline:scale=sqrt:colors=0xffffff[waveform] ; [baserect][waveform] overlay=0:155 [v1] ;[v1][Color] overlay=x=’if(gte(t,0), -W+(t)*64, NAN)’:y=155:format=yuv444[v2]" -map "[v2]" -map 1:a -c:v libx264 -crf 35 -ss 0 -t 20 -c:a copy -shortest -pix_fmt yuv420p -threads 0 output_withwave_and_progresbar.mp4

  

  But I want to show progress inside generated audio waveform instead of making / filling rectangle using drawbox.

  So I have tried to make 2 waveform of 2 different color and overlay on each other and I wanted to show such a way that top waveform should display only part from x position (left) respective to current time.

  ffmpeg -y -loop 1 -threads 0 -i sample_background.png -i input.mp3 -filter_complex "[0:v]drawbox=0:155:1280:100:gray@1:t=fill[baserect] ;[1:a]aformat=channel_layouts=mono,showwaves=s=1280x100:rate=7:mode=cline:scale=sqrt:colors=0xff0000[waveform] ;[1:a]aformat=channel_layouts=mono,showwaves=s=1280x100:rate=7:mode=cline:scale=sqrt:colors=0xffffff[waveform2] ; [baserect][waveform] overlay=0:155 [v1] ;[v1][waveform2] overlay=x=’if(gte(t,0), -W+(t)*64, NAN)’:y=155:format=yuv444[v2]" -map "[v2]" -map 1:a -c:v libx264 -crf 35 -ss 0 -t 20 -c:a copy -shortest -pix_fmt yuv420p -threads 0 test.mp4

  But I am not able to find way to do Wipe effect from left to right, currently it is sliding (as I am changing x of overlay)
  It might be done using alpha merge and setting all other pixel to transparent and only show pixels which are less than x pos.
  but I am not able to find how to do this.

  Background image :
  

  we can use any mp3 file file, currently I have set 20 sec duration.

  Can someone please guide how we can do this ?

  Thanks.

• ffmpeg replace part of audio file with looped audio

  1er décembre 2015, par user1202648

  I am quite new to ffmpeg and I am trying to replace a part of a first audio file with another second file. The second file can be too short, so some sort of loop should exist.

  After some research I came up with the following command arguments and it gives me the output as long as I only do one replacement. But I would like to do multiple replacements. So any help on what I am doing wrong ? Any suggestions/remarks on the way of working are also very welcome.

  (Any typos in the commands below can be ignored, I generate the command by script and for ease of use I simplified the names.)

  Works (One replacement) :

  "ffmpeg.exe" -y -i "first.wav" -i "second.wav" -filter_complex "[1:a][1:a][1:a]concat=n=3:v=0:a=1,asetpts=PTS-STARTPTS[replaceBase];[0:a]atrim=0:3,asetpts=PTS-STARTPTS[partA];[replaceBase]atrim=0:2,asetpts=PTS-STARTPTS[replaceA];[0:a]atrim=start=5,asetpts=PTS-STARTPTS[partB];[partA][replaceA][partB]concat=n=3:v=0:a=1[aout]" -map "[aout]" Out.wav

  Works Not (Multiple replacements) :

  "ffmpeg.exe" -y -i "first.wav" -i "second.wav" -filter_complex "[1:a][1:a][1:a]concat=n=3:v=0:a=1,asetpts=PTS-STARTPTS[replaceBase];[0:a]atrim=0:3,asetpts=PTS-STARTPTS[partA];[replaceBase]atrim=0:2,asetpts=PTS-STARTPTS[replaceA];[0:a]atrim=5:4,asetpts=PTS-STARTPTS[partB];[replaceBase]atrim=0:2,asetpts=PTS-STARTPTS[replaceB];[0:a]atrim=start=6,asetpts=PTS-STARTPTS[partC];[partA][replaceA][partB][replaceB][PartC]concat=n=4:v=0:a=1[aout]" -map "[aout]" Out.wav

  ffmpeg version N-76860-g72eaf72 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 5.2.0 (GCC)
  configuration : —enable-gpl —enable-version3 —disable-w32threads —enable-avisynth —enable-bzlib —enable-fontconfig —enable-frei0r —enable-gnutls —enable-iconv —enable-libass —enable-libbluray —enable-libbs2b —enable-libcaca —enable-libdcadec —enable-libfreetype —enable-libgme —enable-libgsm —enable-libilbc —enable-libmodplug —enable-libmp3lame —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-libopenjpeg —enable-libopus —enable-librtmp —enable-libschroedinger —enable-libsoxr —enable-libspeex —enable-libtheora —enable-libtwolame —enable-libvidstab —enable-libvo-aacenc —enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libwavpack —enable-libwebp —enable-libx264 —enable-libx265 —enable-libxavs —enable-libxvid —enable-libzimg —enable-lzma —enable-decklink —enable-zlib
  libavutil 55. 9.100 / 55. 9.100
  libavcodec 57. 16.100 / 57. 16.100
  libavformat 57. 19.100 / 57. 19.100
  libavdevice 57. 0.100 / 57. 0.100
  libavfilter 6. 15.100 / 6. 15.100
  libswscale 4. 0.100 / 4. 0.100
  libswresample 2. 0.101 / 2. 0.101
  libpostproc 54. 0.100 / 54. 0.100
  Guessed Channel Layout for Input Stream #0.0 : stereo
  Input #0, wav, from ’3897583stereo.wav’ :
  Duration : 00:00:12.07, bitrate : 256 kb/s
  Stream #0:0 : Audio : pcm_s16le ([1][0][0][0] / 0x0001), 8000 Hz, 2 channels, s16, 256 kb/s
  Guessed Channel Layout for Input Stream #1.0 : stereo
  Input #1, wav, from ’beep-021.wav’ :
  Metadata :
  encoder : Lavf57.19.100
  Duration : 00:00:00.30, bitrate : 1413 kb/s
  Stream #1:0 : Audio : pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, 2 channels, s16, 1411 kb/s
  [wav @ 057242c0] Invalid stream specifier : replaceBase.
  Last message repeated 1 times
  Stream specifier ’STREAM CUT matches no streams.

  Thanks in advance !