Adding Audio Clips to Your Web Site

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Updated December 23, 1998

Sound Bytes Clip Comparisons: Does finessing matter? Also known as "more bandwidth=higher quality." 23,175 Kbps -- finessed 23,175 Kbps -- not finessed 9,558 Kbps -- finessed 9,558 Kbps -- not finessed

One of the first things people want to know when they start exploring Windows Media Technologies (WMT) is how to add simple audio clips to their Web site.

In this topic, we'll tell you how we created the audio clips for the WMT Solution: Radio tutorial, and also tell you how to create clips if you're not able to purchase one of the third-party tools we used.

1. Determine the bandwidth of each feed you will offer. Will you offer only 28.8-Kbps feeds, or a variety to accommodate users on high-speed modems?
2. Calculate how much bandwidth you'll need by estimating the total number of concurrent connections you will have for each bandwidth.
3. Get your system ready to record audio.
4. Capture the audio. You can either record to tape first, and then capture from tape to a WAV file, or record straight to a WAV file. In our case, we recorded to a DAT audio tape recorder made by Tascam (model DA-P1) first because the recorder is portable, and we didn't have to worry about the capture process while we were doing the interview. Be sure to use a high-quality microphone as well. We use a $50 microphone from a local Radio Shack and get good results. Once the audio was recorded to tape, we captured it using a Creative Labs SoundBlaster AWE64 Gold card. There are many other audio capture cards that will do a good job for you.
   
   We use Sonic Foundry Sound Forge to capture and finesse audio. All you need to do is hook the audio source up to your capture card (see your capture card's manual for instructions), press play on the recorder, press record in Sound Forge, and then tell it how you would like to capture the audio. We capture to PCM at 44,100 hZ, 16-bit mono. It's important to capture with high quality so that when the compression algorithm works on it, it has more data to draw from to recreate the sound at low bandwidths. If you don't have Sound Forge, most audio cards come with software that can be used to capture audio.
5. Optional: Finesse the audio. We like to run our audio through some pre-processing to get it into shape and get all clips consistent before we compress. Note that when we resample, we resample to match the codec we plan to use. Since we used the MPEG Layer-3 20 Kbps, 11,025 hZ, mono codec, we resample to 11,025 hZ (with anti-alias filter).
6. Convert the WAV file to ASF. We used Sound Forge to do the conversion, but you can also use the Windows Media Encoder or WAVTOASF, which are included in the Windows Media Services . Click the links below for further instructions on how to convert using these tools:
   • Sound Forge
   • Windows Media Encoder
   • WAVTOASF
7. Set up Windows Media Technologies as explained in the WMT:TV Station Feeds tutorial.
8. Create an ASX file.
9. Add the feed to your HTML page or application by linking to or embedding the content.

Note   You can also use the Windows Sound Recorder that ships with Windows to record audio, but note that you won't be able to record more than a few minutes' worth of audio unless you create lower-quality recordings. That's why we recommend checking the software that came with your audio card; most include good programs for capturing audio.