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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 ?

  6 mai 2017, 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

• SIGSEGV from ffmpeg on Amazon Lambda

  1er août 2024, par Serge

  Trying out Amazon Lambda / nodejs 8. My goal is to launch ffmpeg, generate a short clip and upload it to S3 bucket.

  



  I created the function following the image resize tutorial. Edited the code to get output from simple linux commands like ls or cat /proc/cpuinfo - all works.

  



  Now, added the ffmpeg binary for i686 - ffmpeg static build by JohnVan Sickle (thanks !). Changed the code to launch simple ffmpeg command that is supposed to create sa 2-seconds small video clip.

  



  That fails, according to logs, with the signal SIGSEGV returned to the "close" event handler of child_process.spawn()

  



  As far as I understand, this could be caused by the ffmpeg binary incompatibility with the static build. Or by some mistake in my code.

  



  Several npm modules rely on the static builds from johnvansickle.com/ffmpeg and there are no such issues filed on their github. Maybe there's some other mistake I made ?

  



  Should I compile ffmpeg myself under Amazon Linux AMI amzn-ami-hvm-2017.03.1.20170812-x86_64-gp2 which is under the hood of AWS Lambda ?

  



  ---

  



  upd. Launched EC2 t2.micro instance from the same AMI, downloaded the same ffmpeg static build, and it works just fine from the command line. Now I doubt that it is a compilation issue.

  



  Also tried copying ffmpeg executable to /tmp/ffmpeg and chmod 755 just to make sure.
Running simple ffmpeg --help command via child_process.execSync() returns "Error : Command failed : /tmp/ffmpeg —help"

  



  ---

  



  const join = require('path').join;
const tmpdir = require('os').tmpdir;
const process = require('process');
const fs = require('fs');
const spawn = require('child_process').spawn;
const exec = require('child_process').exec;

const async = require('async');
const AWS = require('aws-sdk');
const util = require('util');

process.env['PATH'] = process.env['PATH'] + ':' + process.env['LAMBDA_TASK_ROOT'];


const tempDir = process.env['TEMP'] || tmpdir();
const filename = join(tempDir, 'test.mp4');
const s3 = new AWS.S3();


exports.handler = function(event, context, callback) {
  var dstBucket = srcBucket + "resized";
  var dstKey  = "render-test.mp4";

  async.waterfall([
    function transform(next) {
      var args = [
        '-filter_complex',
        '"testsrc=r=25:s=640x480:d=3"',
        '-an',
        '-y',
        '-hide_banner',
        '-c:v', 'libx264',
        filename,
      ];

      console.log("Will launch ffmpeg");
      const childProcess = spawn('ffmpeg', args);

      childProcess.on('close', function(e) {
        console.log('ffmpeg close event: ' + JSON.stringify(arguments));
        next();
      });

      console.log("After launched ffmpeg");
    },

    function upload(next) {
      ...
    }
  ], function (err) {
    ...
  });
};


  


• ffmpeg : How to use blackdetect filter and cut black frames at once

  25 juin 2012, par cache

  I use the following command to detect black screen interval :

  " ffmpeg -i black.mp4 -vf blackdetect=d=1:pic_th=0.70:pix_th=0.10 -an -f null "

  and it gives me output containing this line :
  "[blackdetect @ 0x219a580] black_start:0 black_end:1.44 black_duration:1.44"

  Now I want to cut off black screens in the video from 0-1.44s.

  So my question is : How to use blackdetect filter and cut black frames at once

  Thanks !