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• FFmpeg scale and concat with dynamic height

  21 août 2018, par Praveen Tamil

  Hi below is the code I’m using to concat multiple images.

  ffmpeg -loop 1 -t 1 -i img1.jpeg -loop 1 -t 1 -i img2.jpeg -loop 1 -t 1 -i img3.jpeg 
  
  -loop 1 -t 1 -i img4.jpeg -filter_complex "
  
  [0:v]scale=640:480:force_original_aspect_ratio=decrease, pad=640:480:(ow-iw)/2:(oh-ih)/2[v0];
  
  [1:v]scale=640:480:force_original_aspect_ratio=decrease, pad=640:480:(ow-iw)/2:(oh-ih)/2[v1];
  
  [2:v]scale=640:480:force_original_aspect_ratio=decrease, pad=640:480:(ow-iw)/2:(oh-ih)/2[v2];
  
  [3:v]scale=640:480:force_original_aspect_ratio=decrease, pad=640:480:(ow-iw)/2:(oh-ih)/2[v3];
  
  [v0][v1][v2][v3]concat=n=4"  output.gif

  But I’m getting below issue

  

• ffmpeg : Infinite amount of filters/crossfading dynamic playlist

  30 juillet 2019, par MaPePeR

  I want to use ffmpeg to play a dynamic playlist infinitely. The idea is, that an external command/script is executed to request the path to the next file (using the predicted start-time of the file as an argument) and continue playing files infinitely.

  From the answer to "Using FFMPEG to stream continuously videos files to a RTMP server" i learned, that i need to write a custom demuxer, that is similar to the concat demuxer. The problem arises from the fact, that i want to crossfade between the audio files and from my understanding of the demuxer i would have to implement that functionality into the demuxer itself to be able to do it, because a demuxer can only produce one (or a finite number) audio output stream and you need two to use the acrossfade-filter.

  So i would have to set up the filter graph like this :

  file1 --------------------------------*-->| cross | ---->more filters ---> Output
  
  file2 -----------------*-->| cross |----->| fade  |
  
  file3 --*-->| cross |----->| fade  |
  
        ... ->| fade  |

  Using an infinite number of crossfade-filters.

  Also i would really like to pre-filter(*, e.g. silenceremove) the audio files before cross-fading, which makes it even more complicated and the "implement everything in the demuxer"-approach even worse.

  My current solution would be to implement a custom demuxer that alternates between two output streams and does the prefiltering internally as well as an input-alternating crossfade filter like this :

  files -> | alternating |----->| alternating | ----> more filters--->
  
           |   demuxer*  |----->|  crossfade  |

  The problem i see with this approach is that i would need to send multiple EOF-terminated files from the demuxer to the crossfade-filter and i don’t know if that is even possible/allowed when using the standard ffmpeg functions like ff_request_frame.

  Can you tell me if this approach is feasible or do you have a better solution to this problem or any idea that would make this easier ?

• Parse dynamic mpd file with Media Source Extensions

  17 février 2023, par FrankC

  I just started learning about adaptive streaming, and currently I'm working on a project that needs showing a live video. In order to control some of the elements in mpd file, I determined to use MSE instead of dash.js. I refer to the code at the following URL :https://learn.microsoft.com/en-us/previous-versions/windows/internet-explorer/ie-developer/samples/dn551368(v=vs.85)
But I found out that there is no "Initialization" tag or "range" attribute in my mpd file. I don't find any relative attribute as well. By the way I'm use nginx-rtmp + ffmpeg to generate dash file.
So here is my dash file looks like

  


  &lt;?xml version="1.0"?>&#xA; &#xA;  <period start="PT0S">&#xA;    &#xA;      &#xA;        &#xA;          <segmenttimeline>&#xA;             <s t="0" d="10000"></s>&#xA;             <s t="10000" d="10000"></s>&#xA;             <s t="20000" d="5000"></s>&#xA;             <s t="25000" d="10000"></s>&#xA;          </segmenttimeline>&#xA;        &#xA;      &#xA;    &#xA;  </period>&#xA;&#xA;

  


  My question is :
1.Did I have any missing parameters in using ffmpeg or nginx-rtmp resulting in losting tag in mpd file ?
2.Or there is other way to setup "Initialization"/"range" attribute and let my program work ?
3.I also curious about why my mpd file doesn't have a baseURL element ?

  


  ※My mpd file works fine with dash.js, I can see the video properly

  


  THANKS A LOT