Authoring an On-Demand MP3 File


Although you'll be using previously prepared uncompressed audio files in these examples, in creating on-demand files, both Audiograbber and iTunes support one-step ripping and encoding directly from a CD into an MP3-encoded file. If you don't need to do additional processing (EQ, compression, and so on), don't bother making the separate steps of ripping CD audio to WAV or AIFF files and then encoding those files to MP3.

Using Audiograbber and LAME

Audiograbber doesn't automatically come with a codec to encode to MP3. When Audiograbber is launched on a Windows computer, it detects an MP3 encoder (if any) within the Windows OS. Because Audiograbber usually chooses a Windows add-on with limited capabilities, you can download a free plug-in for Audiograbber called LAME (for: "Lame Ain't an MP3 Encoder"). With LAME available to Audiograbber, you can encode MP3 files up to 320Kbps.

If you don't have it already on your Windows computer, go to www.audiograbber.com-us.net/download.html and download version 3.89 or later. As of this writing, a fully enabled version of Audiograbber costs $29.95 and is well worth having.

Download the free LAME plug-in for Audiograbber from www.win32lame.com. The download is free (see the Appendix, for information about licensing and using LAME). Follow the instructions on the download site to extract the files into your Audiograbber directory (the default location is C:\audiograbber). After installation the LAME plug-in is automatically detected when Audiograbber is launched as an available MP3 encoding engine.

You're going to use Audiograbber and LAME to encode a song with vocals for delivery to a target audience of listeners who have connections ranging from dial-up (56Kbps) to broadband (DSL 384Kbps). (Refer to Chapter 2, "Preparing Yourself," to learn how to create an AIFF or WAV file.) Because this is an on-demand file, you get to upload and stream it from a SHOUTcast or Web server. (See the section called "Creating a Server," later in this chapter, and Chapter 7, "Serving Your Audio.")

STEP-BY-STEP TITLE: Using Audiograbber and LAME to Author an On-Demand MP3 File

graphics/01icon04.gif
  1. Launch Audiograbber and select Settings, General Settings. This is where you set the music folder for your encoded files. You can also choose any number of simple (or complex) methods for how to name them and sub-directories in which to put them.

    1. Next to Directory to Store Files in the General Settings window, click on the Browse button to select your desired main music folder directory.

    2. Under Create Filenames From, check the boxes next to the items on which you would like your encoded file's names to be based.

    3. Under Sub Directories, (see Figure 6.1) you can select directories in which to place your files (under the main music folder). Some of these values are pulled from the track's ID3 values and are especially useful when ripping large numbers of CDs into a music library. For individual on-demand file creation, Audiograbber's defaults are fine, so don't bother wasting time weighing the different options.

      Figure 6.1. Select the destination directory and method to name new files in Audiograbber's General Settings window.

      graphics/06fig01.gif

    4. When finished, click OK.

  2. Click on the MP3 icon or go to Settings, MP3 to bring up the MP3 Settings window (see Figure 6.2).

    Figure 6.2. Choose the appropriate settings for your on-demand MP3 file in Audiograbber's MP3 Settings window.

    graphics/06fig02.gif

  3. Select your MP3 Encoding Engine by checking Internal Encoder (in the middle of the MP3 Settings pop-up window). Select the LameEnc DLL from the pull-down option list directly below the Internal Encoder checkmark.

  4. Select Constant Bit Rate. Do this because the LAME encoder doesn't support a variable bit rate below 90Kbps, and you're encoding to a 32Kbps on-demand MP3 file.

  5. Choose 32 on the horizontal slider to set 32Kbps for your 56Kbps modem users. If you are creating for broadband users, select 192 for 192Kbps.

  6. For the number of channels, choose Mono for your 56Kbps modem users. For your broadband users, choose the setting Stereo.

    NOTE

    Dual Stereo uses half of the total bit rate for each channel. This is what you're used to with uncompressed CD audio. Choosing Stereo varies the bit rate used for each channel as needed. Choosing Joint Stereo (the best choice for bit rates under 128Kbps) encodes certain frequencies in mono to save space.

  7. From the choices Voice, Low, Normal or High, choose High. (Only select Voice when you are encoding spoken word.) You won't notice a huge audio quality difference between Low and High, but if you're not in a rush, High will sound slightly better.

  8. Leave the Bitstream Flags as they are. Most format players don't pay attention to them.

  9. Leave the Encoder Priority slider at Normal. Only adjust the slider if you want to do other tasks on your computer and don't want the encoder to take up all your processing resources while encoding a large number of files.

  10. Check the Use ID3v1 Tag option to include ID3 tag information in your encoded file and click Edit to bring up the ID3 Tag Editor pop-up window (see Figure 6.3). Fill out the information and click OK.

    Figure 6.3. Enter your MP3 file attributes in Audiograbber's ID3v1 Tag Editor.

    graphics/06fig03.gif

    NOTE

    The title you enter in the ID3 Tag Editor window is only used if you are encoding a single file. When batch encoding (see Chapter 13), the filename of each source file is used to determine the title in the encoded MP3 file's ID3 tag.

  11. Under the Create an MP3 Now text, click the Browse button to locate and select your source WAV file(s). After selecting the desired files, click Open and the encoding process begins immediately. A status window appears including elapsed time and time remaining to completion (see Figure 6.4). When the status window disappears, the encoding process is complete.

    Figure 6.4. The Audiograbber status window shows the file's encoding progress.

    graphics/06fig04.gif

  12. Test your file(s) using a local (on the same computer) MP3 player.

  13. To encode a file for your prospective 384Kbps DSL broadband listeners, repeat steps 4 12. Choose Variable Bit Rate in step 4 (leave the VBR Method set to Default and select the highest quality on the horizontal slider) and select Stereo in step 6.

NOTE

When you run the encoder again for this high bit rate file, the encoder will add a suffix to the filename to avoid overwriting the first one. For example, if your source WAV file is sample.wav, your first encoding will be sample.mp3 and your second encoding will be sample-1.mp3. You should rename them as you see fit.


You now have two MP3 on-demand streaming files in your chosen folder, ready to be slapped onto a Web server or tossed into the correct directory of a SHOUTcast server (see below). Open them with your MP3 player and verify that they sound okay.

Using iTunes

Make sure you're running the latest version of iTunes. Macintosh computers purchased after July 2001 might have it already installed. To get the free download of the iTunes system, go to www.apple.com. You must be running Macintosh OS 9.0 (minimum) or later to install and use iTunes.

As in the Audiograbber Step-by-Step, you're going to use iTunes to encode a song with vocals for delivery to a target audience of listeners who have connections ranging from dial-up (56kbps) to broadband (DSL 384Kbps).

STEP-BY-STEP: Using iTunes to Author an On-Demand MP3 File

graphics/01icon01.gif
  1. Launch iTunes on your Macintosh computer. Go to Edit, Preferences (graphics/01icon05.gif+Y) to bring up the Preferences window.

  2. Select the Importing tab and set the Import Using option to MP3 Encoder (see Figure 6.5).

    Figure 6.5. Set your iTunes importing preferences to use the MP3 encoder.

    graphics/06fig05.gif

  3. For Configuration, select one of the three available built-in default bit rates; alternatively, choose Custom to create your own, which pops up a new MP3 Encoder window (see Figure 6.6).

    Figure 6.6. Select your desired custom settings in iTunes' MP3 Encoder Preferences window.

    graphics/06fig06.gif

    NOTE

    For the purposes of this book, you'll choose Custom because none of the default templates provide VBR or encoding below 128Kbps.

  4. Select 32 Kbps for both Mono and Stereo within the Custom pop-up window and check Use Variable Bitrate Encoding (VBR). Unlike some VBR-enabled, MP3 encoding software, iTunes uses the specified bit rate as the guaranteed minimum bit rate. For VBR Quality, start at Medium (you might want to play with this value because it slightly changes both the audio quality and size of the encoded file).

  5. Keep the default values checked for Smart Encoding Adjustments. (This allows the iTunes MP3 encoder to choose sample rate or channel number if either of those individual choices is set to Auto.) Also keep the default for Filter Frequencies Below 10Hz and Sample Rate at Auto.

  6. Select Mono from the Channels option for your 56K modem users setting. For your broadband users, choose Auto, which encodes to the same number of channels as your source file.

  7. In the Stereo Mode setting, choose Normal when authoring for broadband users. This setting is ignored when Channels is set to Mono (as is done when you are authoring for 56K users).

    NOTE

    Choosing Normal for Stereo Mode varies the bit rate used for each channel as needed. Choosing Joint Stereo (the best choice for bit rates under 128Kbps) encodes certain frequencies in mono to save space.

  8. Click OK to exit the MP3 Encoder window.

  9. In the Preferences window, click the Advanced tab to set your Music Folder Location (see Figure 6.7). Click Change if you want to specify a different folder than displayed. This is where your iTunes MP3-encoded files are placed. Remember this location!

    Figure 6.7. Select your desired music folder location in iTunes' Advanced tab of the Preferences window.

    graphics/06fig07.gif

  10. Click OK again to exit Preferences.

  11. Choose Advanced, Convert to MP3. A Choose Object window opens.

  12. Select your AIFF source file(s) and click Choose. iTunes immediately begins encoding the source file(s). The files that you have selected to encode appear in the main iTunes window, and a status bar tells you the process of the encoding (see Figure 6.8).

    Figure 6.8. iTunes's main window shows the encoding status of your on-demand MP3 file.

    graphics/06fig08.gif

  13. It's possible to listen to music from your iTunes playlist during the encoding process. A chime sounds indicating that your file(s) are finished. Look in your Music Folder Location and test the files with the iTunes player (see Figure 6.9).

    Figure 6.9. Test your encoded file by playing it back in iTunes.

    graphics/06fig09.gif

  14. Re-encode your source file for broadband listeners by repeating steps 2 13, setting the bit rates to 192 Kbps in step 4, and Channels to Auto in step 6.

You've just used a shortcut to speedily convert a source audio file into the MP3 format, bypassing the ID3 tag settings (name, artist, album, and so on). Because iTunes uses ID3 values to determine where in the Music Folder hierarchy to place your MP3 files, the files will most likely end up in the Unknown Album folder below the Unknown Artist folder in the Music Folder. If your source AIFF file already has ID3 information, that ID3 information is included in the encoded MP3 file, which is then placed in the appropriate artist and album name subfolders in the Music folder. If your encoded MP3 files don't have the ID3 information, add this information by following the instructions under "Changing Your On-Demand File Attributes" in Chapter 7, "Serving Your Audio."



Streaming Audio. The FezGuys' Guide
Streaming Audio: The FezGuys Guide
ISBN: B000H2N1T8
EAN: N/A
Year: 2001
Pages: 119

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net