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• FFMPEG : titlecard for concatentaed video results in slow-mo

  3 septembre 2020, par epilitimus

  I have three clips I have extracted from a longer video. When I concatenate them together everything works fine, as would be expected since they all came from the same source.

  


  Now I want to add a title card to the front of the merged video.

  


  I generated an image in GIMP with the same dimensions as the video frames and then used ffmpeg to generate a 5 sec. video from it. When I concatenated it onto the front of the other three I run into problems.

  


  The title card segment plays correctly and then the remaining segments are (both video and audio) in slow-mo. Also the titlecard runs longer than 5 sec and the main segment audio starts before the corresponding video.

  


  I know the problem is with the generation of the title card clip but so far I can't figure out what I am missing. Obviously my bitrates are wrong but how do I get them to match up ?

  


  what I have so far :

  


  my generation script :

  


  #!/bin/bash

ffmpeg -y -ss 0:03:33 -t 0:0:33.5 -i seg1.vob -filter:a "volume=4" seg1.mp4
ffmpeg -y -ss 0:13:25.5 -t 0:0:57 -i seg1.vob -filter:a "volume=4" seg2.mp4
ffmpeg -y -ss 0:16:25.5 -t 0:0:43 -i seg1.vob -filter:a "volume=4" seg3.mp4
ffmpeg -y -ss 0:7:10 -t 0:0:10 -i seg1.vob -filter:a "volume=4" -vn -b:a 394k title.mp3
ffmpeg -y -loop 1 -i title.png -t 0:0:5 -i title.mp3 -c:a aac -b:a 394k -shortest title.mp4 
ffmpeg -y -f concat -safe 0 -i contents.txt -c copy merged.mp4 


  


  and contents.txt :

  


  file 'title.mp4'
file 'seg1.mp4'
file 'seg2.mp4'
file 'seg3.mp4'


  


  ffprobe on seg1.mp4 :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'seg1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf58.20.100
  Duration: 00:00:33.52, start: 0.000000, bitrate: 677 kb/s
    Stream #0:0(und): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 720x480 [SAR 32:27 DAR 16:9], 275 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 6 channels, fltp, 394 kb/s (default)
    Metadata:
      handler_name    : SoundHandler


  


  and for title.mp4 :

  


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'title.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2mp41
    encoder         : Lavf58.20.100
  Duration: 00:00:05.02, start: 0.000000, bitrate: 1290 kb/s
    Stream #0:0(und): Video: mpeg4 (Simple Profile) (mp4v / 0x7634706D), yuv420p, 720x480 [SAR 191:194 DAR 573:388], 898 kb/s, 25 fps, 25 tbr, 12800 tbn, 25 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 389 kb/s (default)
    Metadata:
      handler_name    : SoundHandler


  


• How to pass a youtube video's audio url as ffmpeg source

  8 janvier 2020, par CrystallVR

  Im trying to get my discord bot to play the audio from any youtube videos using the video’s url from youtube-dl (the audio url) as the ffmpeg path/source. I got it to work kind of but, while testing, the ffmpeg throws an error in the middle of the audio and the process ends. Here is the error :
  https://i.imgur.com/uCy8SfK.png

  I’ve tried to play the same exact song by downloading it and using the file’s path as ffmpeg source path and it worked fine.

  Here is how i start the ffmpeg process :

              return Process.Start(new ProcessStartInfo
  
              {
  
                  FileName = "ffmpeg.exe",
  
                  Arguments = $"-xerror -i \"{path}\" -ac 2 -f s16le -ar 48000 pipe:1",
  
                  UseShellExecute = false,
  
                  RedirectStandardOutput = true
  
              });

  path is the audio url from youtube-dl process. (can also see the url in the error screenshot)

  And here is how i get the link from youtube-dl :

  Process youtubedl;
  
  
  
  
  
                  ProcessStartInfo youtubedlGetTitle = new ProcessStartInfo()
  
                  {
  
                      FileName = "youtube-dl",
  
                      Arguments = $"--get-title --get-duration --get-url {url}",
  
                      CreateNoWindow = true,
  
                      RedirectStandardOutput = true,
  
                      UseShellExecute = false
  
                  };
  
                  youtubedl = Process.Start(youtubedlGetTitle);
  
                  youtubedl.WaitForExit();

  url is a normal youtube video link.

  I just started working with ffmpeg and youtube-dl so there probably are some stupid rookie mistakes that i’m not aware of. I would appreciate any guidance and/or explanation of what I did wrong.

• How to speed ffmpeg transform on Raspberry Pi 4 8gb

  19 décembre 2023, par Boaztheostrich

  I am attempting to rotate a 1920x1080 video stream coming into my pi from a elgato usb capture card. This is then being output as a 480x800 stream.

  


  Currently I have about 5 seconds of latency, I am trying to reduce this as much as possible.

  


  Here is my current command.

  


  ffmpeg -f v4l2 -input_format yuyv422 -r 30 -i /dev/video0 -vf "transpose=1,scale=800:480,format=yuv420p" -c:v h264_v4l2m2m -b:v 250k -f h264 pipe:1 | ffplay -fflags nobuffer -


  


  Thanks !