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• Scaling videos for device that doesn't support aspect ratio metadata

  18 juillet 2017, par forthrin

  I have hundreds of videos which are all approximately 4:3 format, but with different resolutions and various cropping (eg. videos may be 640x480, 640x470, 630x480, etc.).

  I converted the videos into a fixed screen size (160x128) for a primitive device. When playing the videos on the device, some appear "thin", while in VLC on my computer, the aspect ratio is correct.

  I assume the reason for this is that the video player on the primitive device doesn’t honour the aspect ratio metadata in the video file. Here are two examples of metadata :

  • 320x240 SAR=1:1 DAR=4:3 (Displays correctly on device and desktop)
  • 480x480 SAR=4:3 DAR=4:3 (Displays thin on device, correct on desktop)

  How can I create a general command line that will give all videos correct playback on my primitive device, regardless of their original size and aspect ratio ?

  The best would be to somehow ask ffmpeg to remove the metadata, and compensate for it when scaling. Another possible option would be to add black bars so the video is always 160x128 pixels.

  I’m open to any solution. Below is my current version :

  for f in *; do ffmpeg -i $f -vcodec mpeg4 -vf scale=160:-1 out/$f; done

• how to concat two videos in ffmpeg with adelay ?

  4 janvier 2023, par SMART

  i have 2 videos : outs.mp4 & V2.mp4 .

  


  outs.mp4 is 4 seconds long (no audio).

  


  V2 is 30 seconds long with audio .

  


  now , i want to concat these files ,when i concat , 2nd video's audio is playing at 00:00:00 . what i want is 2nd video's audio should start play after 4 seconds, 00:00:04.002 . so tried this command ,but it runs forever .

  


  ffmpeg -i outs.mp4 -i V2.mp4 -filter_complex "[0:v][1:v]concat=n=2 [v] ;[1:a]adelay=4s [a] ;[a]amix=inputs=1 [a1]" -map "[v]" -map "[a1]" -y output.mp4

  


  what to do ? how to concat 2 or more videos (with or without audio) [audio should match with the video] in ffmpeg ?

  


• MP4 Videos on website embed with html5 does not play on iOS

  31 août 2012, par Sidner

  So I have a couple of videos on my website that I shot using the iPhone 4 and then converted to mp4, webm and ogg, so that I can use them with html5. Thing is, the video does not play at all on the 4 iOS devices that I tested and neither on Chrome for Android.

  The Chrome issue could be because some of the mp4 are actually m4v files, but still after encoding with handbrake a video to the iphone 4 presset and in mp4 format, it still does not play.

  What happens, you ask ? Well, it shows the play button crossed out with a diagonal bar, the debug console on Safari does not show any message untill I try to access the video directly. Then it says : QuickTime Movie could not be played.

  What can I do ? I have been trying to encode with ffmpeg, have tried a handful of different solutions, some even found here on stackoverlow, but to no avail. The videos do get shorter, both in display size and MBs, but nothing works to fix the issue at hand.

  I've been trying to get this corrected for a couple of weeks now. Any help and/or suggestions are welcome.

  Thank you.

  By the way, all the videos are on a registred users section of the website, but I have one for debugin on the main page, so feel free to test.

  https://sidnerwebsite.sytes.net