2 Replies Latest reply on Jun 30, 2011 5:26 AM by fenke

    Splitting up a movie; file sizes don't make sense

    fenke Level 1

      Okay that's one way to compress my problem, I hope people can make sense of it

       

      Basically I've got a collection of hour-long movies I need to break up into 15-minute chunks for youtube. They are 640x480 29fps FLV movies, roughly about 200mb in weight, and I'm opening my Premiere Pro project at those very parameters. The problem I'm having though is that whenever I export each 15 minute clip, logically the filesize should be about 50mb, a quarter of that of the whole movie, but it generally exports at about 100mb. Now I've set my export settings as "match source attributes", and I've not altered the movie in any way. Is there something crucial I'm missing?

        • 1. Re: Splitting up a movie; file sizes don't make sense
          Colin Brougham Level 6

          The problem I'm having though is that whenever I export each 15 minute clip, logically the filesize should be about 50mb...

           

          Not so. The duration of an exported video is only one factor in determining the size of a file, and it's a relatively minor one. The primary determinant of video file size is bit rate; you must set the export bit rate at or below the bit rate of your original footage. Roughly doing the math, your original file is no more than 550kbps, which would be the combined bit rate for the video, audio, and container file. Compressing a file at that bit rate which is already compressed quite heavily is going to result in a very poor looking image; Premiere does not do "smart encoding" with formats like FLV, so there is no way to avoid the recompression. You'd be better off finding a tool to split the original FLV; there are freeware and payware ways to do this.

           

          Now I've set my export settings as "match source attributes", and I've not altered the movie in any way.

           

          Don't use "Match Source" for exports; it doesn't do quite what you think it would do. You will need to manually select the format, codec, and encoding parameters to match your desired output (presumably, you're going back to FLV). However, see the above caveats; you'll be recompressing the file no matter what you do.

          1 person found this helpful
          • 2. Re: Splitting up a movie; file sizes don't make sense
            fenke Level 1

            Wow, that's really insightful and so helpful! I went back and had a fiddle, and literally the only thing I had to alter was the export bitrate -- I lowered it down to 550 (just a number I plucked out based on your response) and not only did it reduce the filesize greatly, but the outputted video was barely any lower in quality! Okay so when small text came up is was a little fuzzy around the edges, but it's still legible! Thanks ever so much for your quick reply.