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• Are their technical reasons is MP4 more popular than Webm ?

  1er juin 2019, par dprogramz

  Not looking for opinions. I’m searching for data.

  As it is now, I want to become a webM evangelist. However, I assume there are some actual technical reasons why mp4 is preferred over webm in the bigger picture. I want to know them so I can be accurate in my assessments.

  I’m working on developing a broadcast video messaging graphics engine (think chyron) and using the Chromium engine like OBS does for messaging. So far the results have been excellent.

  One of the best features I’ve found is using webm for video. I should note I am using small (640x480 max) videos as graphics that are on top off a larger full HD video.

  Not only does it seem to have a better compresion:quality ratio than mp4 for my use case, the most important thing is that it has full alpha support, which allows for excellent layering of video objects on top of each other in the HTML DOM, in real time, with no noticable performance hits.

  Aside from it’s predecessor, FLV, I can’t think of another high quality, high compression codec that also supports alpha. I feel like you are stuck using pro-res 4444 or the ancient animation codec to reliable distribute video with an alpha.

  So, that said, are there technical reasons why webM isn’t more adopted than mp4 ?

  I already know the obvious, that there is dedicated hardware to decode mp4. But, is there any technicality that would prevent a hardware webM decoder ? I really want to understand more what the benefits of mp4 are over webM, which i assume is why it is more widely used than webM.

  Thanks !

• ffmpeg command to combine audio and images

  4 février 2013, par jeet

  I'm trying to achieve something which I earlier thought should be a simple task.
  Is there a ffmpeg command that can do the following :

  convert an audio.wav file to a video,
  Add some 100 pics (img%d.png) to the video so they "automatically" stretch to fill the entire length of the video.

  I don't want to set the frame rate manually because it's either making the audio go ahead or lack behind.

  I also don't want the following to happen, which happenned when I used "loop_input" :

  A short video of images got created, which played fast and then repeated itself for the entire duration of the audio.

  Please let me know the command.

  I've currently tried the following, but these are not giving me the desired results :

  This one makes, but video goes fast and audio is not full :

  ffmpeg -i img%d.png -i audio.wav -acodec copy output.mpg

  This one makes short video which repeats for full audio duration :

  ffmpeg -loop_input -shortest -i img%d.png -i audio.wav -acodec copy output.mpg

  This one works nearly, but "-r 4" makes video go slow and audio goes ahead. If I use "-r 5" then audio goes slow, and video goes ahead :

  ffmpeg -r 4 -i img%d.png -i audio.wav -acodec copy -r 30 output.mpg

• FFMPEG zoompan filter cut short my video and slowed it down [on hold]

  9 décembre 2018, par Ewan Sou

  I am using FFMPEG (version 4.0.2) to zoompan my video. My code is as below

  ffmpeg -y -i input.mp4 -loop 1 -i overlay.png -ss 0 -t 10 -filter_complex "[0:v]scale=iw+iw:ih+ih, zoompan=z='if(lte(pzoom,1.0),1.6,max(1.001,pzoom-0.004))':d=1:x='iw/2-(iw/zoom/2)':y='0':s=720x720, setsar=1 [v0];[1:v]crop=720:720,fade=t=in:st=0:d=1,fade=t=out:st=3:d=1[v1];[v0][v1] overlay [v]" -map "[v]" -f mp4 -preset ultrafast -y output.mp4

  Essentially, what this code should do is slowly pan out from the center of my video, with a logo (overlay.png) fading in and out.

  This input.mp4 is 10 seconds. With the above code, the final video duration is 10 seconds still. But its not the full footage, it is cut short and compensated with slow motion to make it 10 seconds still...

  I need the final video to not be cut off at all. It should be the full footage and no slow motion effect.

  Anyone has any ideas what I am doing wrong ?

  Input video is at : https://instantly.sg/photobooth/input.mp4

  Overlay is at : here

  Thanks in advance !