4 Replies Latest reply: Mar 24, 2009 3:33 PM by _durin_ RSS

    Tin Can Voice

    Rich146 Community Member
      Topic

      Tin Can Voice

      Rich Gilman - 12:30pm Mar 20, 2009 Pacific

      I posted this to the Flash General Forum and wanted to post here for more input since you all are probably more sound focused.

      I am doing some education narration and no matter what I do I still get the "tin can" effect.
      Could you please listen to my narration and look at my methodology? The narrated file is at richgilman.com (or http://216.219.188.90/).

      My Methodology:
      1. Record in Adobe Soundbooth CS3 at 96k htz (sounds great)
      2. Save as mp3 24kbs/sec, Best Quality, Mono (sounds great)
      3. Import to flash with these settings: mp3, 24kps, Quality Best.
      4. Publish: Audio Stream MP3, 24 kbps, mono.

      The one curious issue I see is with the Sound Properties in Flash which says at the bottom "24 kbps Mono 247.6kB, 13.6% of original" WHY WOULD IT BE 13.6% OF ORIGINAL WHEN THE ORIGINAL IMPORT IS A SMALL MP3? (this can be seen on the web link richgilman.com)

      Thank you for your time.

      Rich Gilman
      richgilman.com
        • 1. Re: Tin Can Voice
          Craig Jackman Community Member
          MP3 is a destructive, compression algorhythm. Put simplistically, it "throws out" audio it thinks you can't hear giving the bit rate settings in the MP3 settings you tell it. So if you are recording narration at 96kHz ... which is total and utter overkill for the human voice ... and then compress that down to a 24kbs MP3, you are "throwing away" 86.4% of the data in your original audio file. You will also be going through a stage of sample rate conversion as they don't, to my knowledge, support 96kHz MP3 files.

          If you want to get rid of the tin can effect, you have to use a MUCH high MP3 bit rate. The smallest I ever use is 48kbs mono for a streaming podcast. If I'm sending a voice narration from one studio to another I use 128kbs mono. If I'm sending a stereo file I use 192kbs minimum.

          Basically if you want to pack more audio quality into your MP3 file, you have to make it a bigger file.

          Since you are going to MP3 format, and since it's just voice narration, you are fooling yourself to be recording at 96kHz. All you are doing is wasting disk space. If I was going to end up with a small MP3 file in the end, I'd be recording at CD quality or 44.1kHz. For video, 48kHz.
          • 2. Re: Tin Can Voice
            Rich146 Community Member
            Craig

            Thank you for the feedback. I will start recording at 44.1kHz and increase the MP3 to 48kbps mono. I am sure it will sound better, I was worried about the file size but I guess now days with most users equipped with highspeed internet it does not make that much difference.
            I am glad to know what your settings are for streaming voice.

            Thank you again for your suggestions.

            Rich Gilman
            • 3. Re: Tin Can Voice
              Wild_Duck Community Member
              Rich, I don't know about the Quicktime part of the question (and don't understand the reference to 11kHz mono on the upper of the 2 boxes on your site - surely this is too low whatever it means?), but, like Craig, I have done a lot of mp3 encoding of mono speech files.

              We never used to go below 56kbps as the mp3 data rate, and would usually use 64k.
              We also got better quality by using a starting sampling rate on the original file of 32kHz, which gives adequate audio bandwidth for most uses and leads to less compression.
              • 4. Re: Tin Can Voice
                _durin_ Employee Hosts
                Rich,

                I sent a response to your post in the Soundbooth forum. I think the problem is your RE-Compressing the mp3 files in Flash. Flash gives you the option of recompressing the audio in your library on export, or leaving it at the default settings. the screenshots you posted indicated it was being compressed a second time.

                Durin