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• Video to GIF Conversion with Random Frames on AWS Lambda using Nodejs and ffmpeg

  5 avril 2024, par rahulfaujdar

  I'm seeking assistance with automating the conversion of several videos stored in an S3 bucket into GIFs. Specifically, I aim to generate GIFs that are precisely 10 seconds long, each comprising random frames sampled from different sections of the original video. The randomness should encompass frames from the beginning, middle, and end of each video, ensuring a varied and engaging GIF output.

  


  Currently, I'm in the process of implementing this functionality using Nodejs and AWS Lambda, utilizing ffmpeg for video processing. However, I'm facing challenges in achieving the desired outcome efficiently.

  


  If anyone has experience or insights into how to accomplish this task effectively within the AWS Lambda environment, especially regarding Nodejs code and ffmpeg usage, I would greatly appreciate your guidance and expertise.

  


• how to explicitly specify matroska format file to be VFR

  19 janvier 2012, par Ulterior

  I am moving my code performing AVI recording with ffmpeg library to matroska format due to native support of VFR stated by format. Changing guess_format to matroska not touching any other settings produced an mkv file which seems to be ok. But the MediaInfo reports it to be CFS (30).

  How do I explicitly state that its VFR ?

  Format                           : Matroska
  
  File size                        : 5.27 MiB
  
  Duration                         : 8s 0ms
  
  Overall bit rate                 : 5 528 Kbps
  
  Writing application              : Lavf52.78.1
  
  Writing library                  : Lavf52.78.1
  
  
  
  Video
  
  ID                               : 1
  
  Format                           : MPEG-4 Visual
  
  Format profile                   : Simple@L1
  
  Format settings, BVOP            : Yes
  
  Format settings, QPel            : No
  
  Format settings, GMC             : No warppoints
  
  Format settings, Matrix          : Default (H.263)
  
  Codec ID                         : V_MPEG4/ISO/ASP
  
  Codec ID/Info                    : Advanced Simple Profile
  
  Duration                         : 8s 0ms
  
  Width                            : 1 280 pixels
  
  Height                           : 720 pixels
  
  Display aspect ratio             : 16:9
  
  Frame rate                       : 30.000 fps
  
  Color space                      : YUV
  
  Bit depth                        : 8 bits
  
  Scan type                        : Progressive
  
  Writing library                  : Intel(R) MPEG-4 encoder based on Intel(R) IPP 6.1 build 137.36[6.1.137.779]
  
  Language                         : English
  
  
  
  Audio
  
  ID                               : 2
  
  Format                           : MPEG Audio
  
  Codec ID                         : A_MPEG/L3
  
  Codec ID/Hint                    : MP3
  
  Duration                         : 8s 0ms
  
  Channel(s)                       : 2 channels
  
  Sampling rate                    : 44.1 KHz
  
  Language                         : English

• ffmpeg : map audio and subtitle stream of (different) specific language only

  24 juillet 2019, par RocketNuts

  I have a bunch of video files with multiple audio and subtitle streams (in different languages). The streams contain metadata specifying which stream is which langauge. I want to copy all files but maintaining only the spanish audio streams, and the english subtitle streams (and the video stream of course).

  Unfortunately, not all videos contain the same language streams at the same index, so instead of using something like -map 0:a:2 I am trying to select the streams based on metadata.

  However, if I try the following : (based on answers found in similar questions like this and this)

  ffmpeg -i input.mkv -map 0:v -map 0:a:m:language:spa -map 0:s:m:language:eng -c copy output.mkv

  It still copies the first audio and first subtitle stream, no matter which stream is which language. In other words, this behaves just like -map 0:v -map 0:a:0 -map 0:s:0 which isn’t what I need.

  Is there a different map argument I can use to make sure it picks only the spanish audio stream and only the english subtitle stream, regardless of their index in the input file ?