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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

• NVIDIA accelerated ffmpeg (nvenc_h264 ) is dead slow on Amazon G2 instance

  16 novembre 2015, par Abhijit Pathak

  FFMPEG when compiled with following options give abysmal performance on Amazon G2 instance( g2.2xlarge, GRID K520) when compared with standalone Dell-Precision-T1700 (Quadro-k620)

  "--enable-nonfree --enable-gpl --enable-version3 --enable-shared --enable pthreads [b]--enable-nvenc[/b] --enable-runtime-cpudetect --disable-doc --enable-libmp3lame"

  Above ffmpeg binary took 66 seconds to transcode 5.22 mins BVE_Localize.mp4 file with following command.

  time ffmpeg -y -i BVE_Localize.mp4 -strict -2 -vcodec nvenc_h264 -b 5000k -acodec aac -ab 256k -f mpegts BVELocalize.ts ( took 1m6.990s on G2)

  When same ffmpeg command is executed on Dell-Precision-T1700 (Xeon Dual core, Quadro K620) based workstation takes 0m41.572s.

  I would like ffmpeg to perform better on Amazon G2 instance. What do you think I might be missing ? My Amazon G2 instance configuration is Ubuntu 14.04 64 bit, Cuda 7.0 , 352.55 drivers, MSI disabled,NVIDIA SDK 5.0.1

• Amazon S3 : how to combine all images into a video ?

  17 mars 2015, par scientiffic

  I’m in my Rails app, I enable users to upload images, which get processed using ffmpeg to create a video slideshow.

  I have this working locally, but am wondering how to do this when deploying the app using Heroku. In particular, I know Heroku has limited storage and has a read-only filesystem, so using Carrierwave without S3 or an external storage option doesn’t seem like an option.

  But how would I run a task like the following using S3, where I combine all images into a video ?

  The ffmpeg command is

  ffmpeg -r 5 -i https://s3.amazonaws.com/[]/uploads/image/image_file/26/img%03d.jpg output.mp4 -y

  And the AWS "folder" contains the following :
  https://s3.amazonaws.com/[]/uploads/image/image_file/26/img001.jpg
  https://s3.amazonaws.com/[]/uploads/image/image_file/26/img002.jpg
  https://s3.amazonaws.com/[]/uploads/image/image_file/26/img003.jpg

  When I try to do the following, I get an error with ffmpeg not knowing what to do with :

  https://s3.amazonaws.com/[]/uploads/image/image_file/26/img%03d.jpg

  Note, this whole video compilation process works fine for me locally, so I know in theory it should work.