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• How To Concatenate Two MP4 Videos With Different Aspect Ratios and Resolutions

  11 novembre 2017, par PortableDiag

  I am using ffmpeg to concatenate multiple MP4 videos, two at a time. The problem I am having is that the videos are often different resolutions and aspect ratios. One might come from a 480p webcam with a 1:1 aspect ratio and the other a brand new iPhone with 4k video and rectangular aspect ratio. Currently I must choose and set the aspect ratio manually and this results in one of the two videos becoming distorted, depending on the selected aspect ratio.

  How can I merge two videos so that the overall viewing field has a square aspect ratio but videos with a rectangular aspect ratio will be scaled to fit inside.

  I am using this command to merge the videos :

  ffmpeg -threads 1 -i '/518.mp4' -i '/516.mp4' -y -filter_complex "[0:v]scale=1080x1920,setpts=PTS-STARTPTS,setdar=0/1[v0];[1:v]scale=1080x1920,setpts=PTS-STARTPTS,setdar=0/1[v1];[v0][0:a][v1][1:a]concat=n=2:v=1:a=1" '/partial1.mp4'

  This is the result : https://www.dropbox.com/s/x1un7z1ljwr6tty/merged_newsort.mp4?dl=0

  Is it possible to apply a border to the rectangular video to give them a square aspect ratio ?

  How can I keep prevent distortion from occurring during the merge process ?

  Thanks in advance.

• RTSP Assertion desc failed at libswscale/swscale_internal.h:658

  3 novembre 2014, par Karthik Rao

  In RTSP that I try to play in iPhone 4s(iOS 7.1) I receive following error :

  Assertion desc failed at libswscale/swscale_internal.h:658

  I am using FFmpeg 2.4.2 and built the library using the script

  https://github.com/kewlbear/FFmpeg-iOS-build-script.

  I am using code from DFURTSPPlayer to play RTSP live streaming in iOS 7 devices and above.

  The player will play video for the first time if I reload Video then the app crashes giving the above error.

  The streaming works fine in other iOS 7 devices

  I have found the following thread in github regarding the same issue which is still open.

  Can anyone suggest me to overcome this assertion failed issue.

• Add a 2nd audio stream using ffmpeg so you can switch audio streams on iOS ?

  26 décembre 2019, par Tony M

  I have an m.mp4 with English audio and want to add a second audio stream in Italian so that I can play either language using the iPhone. When I used this command :

  ffmpeg -i m.mp4 -i ita.mp3 -c copy -map 0 -map 1 out.mp4 

  The output from ffmpeg -i out.mp4 (see below) shows that a new audio stream is added, and I can switch between audio streams using the VLC player. Yet when I transfer the video to the TV app and play it on either MacOS or iOS it only plays the original English and I see no options to play other languages.

  How do I get it to be able to switch between either audio on iOS ?

  Here is the output from ffmpeg -i out.mp4:

      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 400x300 [SAR 1:1 DAR 4:3], q=2-31, 482 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 24k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 102 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
      Stream #0:2: Audio: mp3 (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 152 kb/s
  
      Metadata:
  
        encoder         : LAME3.100
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
    Stream #1:0 -> #0:2 (copy)