CODEWITHSUNDEEP
ruby-on-railsrubyvideomp4
Andrew Lor
Andrew Lor

Reputation: 33

Writing an mp4 file in Ruby

I am trying to figure out how to take a string that is the file contents of a mp4 file and write a properly formatted mp4 file. Currently I am just throwing the string into a file and slapping a .mp4 extension on it, but this resulting file cannot be played by any video players (I am assuming because of all the missing meta data).

def write_mp4(mp4_string)
  file = File.new('movie.mp4', 'w')
  file.puts(mp4_string)
  file.close
end

For context, I am doing this in a Ruby on Rails application, not sure if that changes anything. Please help thanks.

Upvotes: 3

Views: 594

Answers (1)

Amadan
Amadan

Reputation: 198314

  • Use "wb" mode, which will suppress EOL conversions and set the encoding properly
  • Use write, not puts, as the latter inserts an extra EOL
  • You could use a shortcut: File.write('movie.mp4', mp4_string, mode: 'wb') - or even File.binwrite('movie.mp4', mp4_string).

Of course, make sure the string actually contains a correct file before - for example, if mp4_string.encoding doesn't return #<Encoding:ASCII-8BIT>, you probably done goofed somewhere before the writing step, too :)

Upvotes: 3

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