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• Optimize ffmpeg overlay and loop filters

  5 novembre 2020, par Miro Barsocchi

  I have a video, video.mp4, of 30 seconds, and I have an audio that can change in length, audio.mp3.

  


  My final idea is to have an output video of a loop of video.mp4 for the total length of the audio.mp3, and an overlay of the waveform of the audio.mp3. What I've done is this, in a bash script :

  


  # calculate length of the audio and of the video
tot=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 audio.mp3)
vid=$(ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 video.mp4)
# how many base video we need to loop into the waveform video?
repeattime=`echo "scale=0; ($tot+$vid-1)/$vid" | bc`

# ffmpeg final command
ffmpeg -stream_loop $repeattime -i video.mp4 -i audio.mp3 -filter_complex "[1:a]showwaves=s=1280x100:colors=Red:mode=cline:rate=25:scale=sqrt[outputwave]; [0:v][outputwave] overlay=0:main_h-overlay_h [out]" -map '[out]' -map '1:a' -c:a copy -y output.mp4


  


  Is there a better way to do it in a single ffmpeg command ? I know it exists the loop filter in ffmpeg, but it loops frames and I don't know the number of frames of the video.mp4. Also, using $repeattime can result in a number of loop longer then needed (because math calculation is done round up)

  


• FFMPEG : Set Opacity of audio waveform color

  13 août 2018, par Software Development Consultan

  I was trying to do transparency in waveform generated. It seems there is not direct option in ’showwaves’ filter so I came across ’colorkey’ which might help.

  I am trying with following :

  ffmpeg -y -loop 1 -threads 0 -i background.png -i input.mp3 -filter_complex "[1:a]aformat=channel_layouts=mono,showwaves=s=1280x100:rate=7:mode=cline:scale=sqrt:colors=0x0000ff,colorkey=color=0x0000ff:similarity=0.01:blend=0.1[v] ; [0:v][v] overlay=0:155 [v1]" -map "[v1]" -map 1:a -c:v libx264 -crf 35 -ss 0 -t 5 -c:a copy -shortest -pix_fmt yuv420p -threads 0 test_org.mp4

  So I wanted to blue color waveform and wanted to set opacity of that 1 to 0 let say. But it seems this generates blackbox which is actual background of ’1280x100’. I want to keep background of waveform transparent and just wanted to change opacity of waveform only.

  Result of my command : enter image description here

  

  Can you please let me know your suggestion

  @Gyan, this is with reference to following question which you have answered.

  Related last question

  Thanks, Hardik

• Finding File Matches & Variable Assignment using a .BAT Script

  6 octobre 2019, par A Person — batch-file, ffmpeg

  I am trying to assign a file to a variable in a batch-file and then also assign another 2 files into anoter variable.

  However, I am having an issue.

  From research, I found how I can do the assigning but does anyone know how I can do the below.

  From a folder or text file, (either is fine), find the .m2v video file and assign that to Var1 then find matching audio in .wav and put that in Var2 and the third is also an audio .wav with mathcing name and assign that to Var3.

  The problem I am having is trying to find the matching 2 audio files to the video.

  The video file is named as :

  PAV_PRG_13683Highc450277201906251802090353.m2v

  Audio 1 is :

  PAV_PRG_13683High01c450211201906251802090376.wav

  Audio 2 is :

  PAV_PRG_13683High00c450211201906251802090368.wav

  The file name matches until it sees the word High. Everything after High is not needed, (it is just a random string), so trying to match is an issue.

  Is there a way to find the match by comparing everything before High.

  Also as I will be using the variable and putting them through ffmpeg to merge, is there way to do it so that when the ffmpeg command has completed, it moves to the next matching files and assigns them to the variable.

  The files are store in 2 folders, one folder has all the video files *.m2v and another folder has all the *.wav audio files in pairs of 2. Each video has exactly 2 audios, (left right).

  is there any help on this subject, I have already come up empty in my research and have been checking for this over the last week spent almost 30 hours.