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• Ffmpeg mixing audio only for n number of videos using offset and altered duraion

  26 août 2022, par Turgut

  I want to mix audio stream of n amount of video files with ffmpeg, with certain parameters such as :

  


  

  • Duration : I want to specify how long each audio is going to play for each output. For example if I specify ffmpeg -i -d:5 first.mp4 -i second.mp4 it should play the audio from first.mp4 for 5 seconds (I don't know if -d:5 is a real tag it's just an example I've made ).

  


  • Starting point : I want to specify when a given file is going start on the output, I probably need to use -itsoffset 5 but I don't know if it's the right one in terms of interacting with other commands, in on itself it works fine. For example : ffmpeg -i -isoffset 5 first.mp -i second.mp4 causes the second.mp4 to start immediately, and first.mp4 to start after 5 seconds.

  


  • Segmentation : This is the tricky one, I want to specify at which point the input's audio should start. It's like the -ss flag but the problem is it's not working together with -itsoffset. For example when I say ffmpeg -i -ss 5 first.mp4 -i second.mp4 both files should start immediately on the output, but first.mp4 should start on it's 5 seconds. So the 5th second of first.mp4 is heard at the 1st second of the output.

  


  


  This is what I'm trying to achieve, my problem is that I don't know how to implement 'duration' and -ss is not working together with -itsoffset.

  


  At the end I should have something similar to this :

  


  ffmpeg -y -d 5 -itsoffset 3.5 -i first.mp4 -d 10 -ss 10 -itsoffset 5.3 -i 3 -vn -copyts -async 1 -filter_complex amix=inputs=2 out.mp


  


  Which should result in an audio that sounds like this : The first 3.5 seconds are empty, no audio is heard. Then first.mp4 is heard from it's beginning for 5 seconds. When the outputs timestamp reaches 5.3, the 10th seconds of second.mp4 is heard (while first.mp4 is still playing, it's supposed to play until 8.5, so I should hear both files at the same time.) for 10 seconds.

  


  I can't find an example of this and some sources are out-of date.

  


• What is the fastest way to create a video with a audio from 200 images ? [closed]

  26 juin 2022, par aiyu

  I have 200 images, every 10th image will have a fade out effect and 11th image will have fade in effect. Fade in and Fade out will be accompanied by SFX tone in addition to a background music. Each image will be 1 second long.

  


  Currently I am rendering the output using Blender. But it takes 5 minutes for a 52 second video.

  


  I am wondering is there a faster way to achieve the same ? Maybe another software or some other techniques ? Please advice.

  


  NB : I could generate this video in few seconds rather than 5 minutes by setting the FPS to 1. I tried generating video at 1FPS for frames with no fading effects, then separately generating video at 24 FPS for those with fading effects and then concat with FFMPEG. But the end result audio was out of sync. Wondering if its because of varying FPS.

  


  NB : I am comfortable working with python.

  


• avformat/mxfenc : fix DNxHD GC element_type

  14 décembre 2021, par Nicolas Gaullier

  avformat/mxfenc : fix DNxHD GC element_type
  The values for the essence element type were updated in the spec
  
  from 0x05/0x06 (ST2019-4 2008) to 0x0C/0x0D (ST2019-4 2009).
  Fixes ticket #6380.
  Thanks-to : Philip de Nier <philip.denier@bbc.co.uk>
  
  Thanks-to : Matthieu Bouron <matthieu.bouron@gmail.com>
  Reviewed-by : Matthieu Bouron <matthieu.bouron@gmail.com>
  
  Reviewed-by : Tomas Härdin <tjoppen@acc.umu.se>
  Signed-off-by : Nicolas Gaullier <nicolas.gaullier@cji.paris>
  
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/mxfenc.c
  • [DH] tests/ref/lavf/mxf_opatom