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• What is the right command to convert an mp3 file to the required codec version (MPEG version 2) and bit rate (48 kbps) for Amazon Alexa SSML ?

  1er février 2019, par Asimov4

  I am trying to convert an mp3 file to the format expected by the audio tag in the Amazon Alexa SSML markup language as described here : https://developer.amazon.com/public/solutions/alexa/alexa-skills-kit/docs/speech-synthesis-markup-language-ssml-reference

  The documentation recommends using https://www.ffmpeg.org/ffmpeg.html

  I tried this command but can’t find the right codec to use :
  ffmpeg -y -i input.mp3 -ar 44100 -ab 48k -codec:a mpeg2 -ac 1 output.mp3

  I know I need to convert the file because Alexa fails with the following error : The audio is not of a supported MPEG version

• Using only ffmpeg, is it possible to consume a source GIF image and output a video that is a set length > one loop through the input GIF ?

  23 octobre 2013, par Thomas Graft

  Let's say I have an 8 frame animated GIF that is 2 seconds long. I would like to build a video file (codec not important at this point) that is 30 seconds long that consists of the source GIF repeating over and over.

  Is it possible to do this using only ffmpeg ? Answers that use convert or some other pre-processing utility do not count [The reason being that I would like to use this on PandaStream, which does not have that utility]. Let's also assume that shell scripts are out of the question as well, though it can be multiple ffmpeg commands.

  ---

  Things I have tried that did not work (though maybe I did them wrong, I'm not terribly familiar with ffmpeg) :

  1. Using the -loop_input, -loop_output options present in the ffmpeg docs. Using both ffmpeg 1.2 and 2.0, I get a Unrecognized option 'loop_[input|output]' error message. I might be using this wrong though since the error is about not recognizing the option, though the docs say it is deprecated.

  2. -loop option. Does not seem to do anything with GIF -> Video. I think this flag and the above flag are related to generating animated GIFs as the output.

  3. Concat. Doing something like :

     ffmpeg -i "concat:image.gif|image.gif|image1.gif|image2.gif|image3.gif|image4.gif" image-long.gif

     Results in a 16 frame gif (so two gifs are concatenated) which is progress, though the output gif is of much lower quality.

  ---

  I'm a bit at my wits end here (I have tried many other permutations of the above concepts), I'm at the point now of 'poking it with a stick', hopefully someone out there has done this !

• Error "sys/videoio.h - not found" OpenCV 3.1.0

  22 mars 2017, par Jefferson Rodriguez

  I using Elementary OS and I’m trying to install OpenCV 3.1.0, I follow the instructions of http://docs.opencv.org/3.0-beta/doc/tutorials/introduction/linux_install/linux_install.html
  Also, I have installed libav 11.7 and ffmpeg 3.1.3
  but, after cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local ..
  I get :
  
  — Looking for linux/videodev.h
  
  — Looking for linux/videodev.h - found
  
  — Looking for linux/videodev2.h
  
  — Looking for linux/videodev2.h - found
  
  — Looking for sys/videoio.h
  
  — Looking for sys/videoio.h - not found
  
  — Looking for libavformat/avformat.h
  
  — Looking for libavformat/avformat.h - found
  
  — Looking for ffmpeg/avformat.h
  
  — Looking for ffmpeg/avformat.h - not found
  
  — checking for module ’libgphoto2’
  
  — package ’libgphoto2’ not found
  And after make,
  I get :
  ../../lib/libopencv_videoio.so.3.1.0 : referencia a

  av_frame_alloc' sin definir <br />
../../lib/libopencv_videoio.so.3.1.0: referencia a

  av_frame_free’ sin definir
  collect2 : error : ld returned 1 exit status
  make[2] : * [bin/opencv_test_video] Error 1
  make[1] : * [modules/video/CMakeFiles/opencv_test_video.dir/all] Error 2
  

  someone who can help me ?