With all the video features in Microsoft Expression Encoder 3 with IIS Smooth Streaming, you may forget that it is also a powerful audio encoding tool. If you have .wav, .mp3 or even .aif files that you want to convert to Windows Media Audio (WMA) or H.264 (MP4) files, or you just want to encode your existing .wma or .mp4 files in a bit rate or sample rate that is more suited to your audience, you can’t go wrong using the high-quality audio encoding options that you have in Expression Encoder.
Note: If you have Apple QuickTime installed, you will have the ability to import additional file formats.
Encoding your audio
Expression Encoder includes audio encoding profiles that match practically any playback scenario that you may want to encode for, including playback in low-bandwidth situations, playback on your Zune, and playback in an HD environment.
To access the audio codecs, click the Encode tab and expand the Profile section. Then, click the Audio menu to expand it.
Audio encoding choices in Expression Encoder
Here is brief explanation of the default codec choices available, and which scenario they are best suited for:
- WMA Audio – Zune 2 Optimized for near–CD-quality playback on your Microsoft Zune player. The default bit rate is 192 kbps, the default sample rate is 48 kHz, and the default codec is WMA.
- WMA HD Audio Optimized for High Definition audio playback. The default sample rate is 44.1 kHz.
- WMA High Quality Audio Optimized for a balance between high-quality playback and efficient storage on your desktop or Zune, as well as high-quality streaming across broadband networks. The default bit rate is 160 kbps.
- WMA Audio – Zune and WMA Good Quality Audio Optimized for standard-quality playback from your Zune player and desktop and for good-quality streaming for most network speeds. The default bit rate is 128 kbps.
- AAC Good Audio – podcast Optimized for standard-quality playback podcasts using the AAC codec in an MP4 container. The bit rate is 128 kbps at 44.1 kHz.
- WMA Medium Quality Audio Optimized for streaming in medium-bandwidth scenarios, and also very good quality for voice-only audio. The default bit rate is 96 kbps.
- AAC Low Audio – podcast Optimized for low-bandwidth streaming scenarios or voice-only podcasts. The bit rate is 96 kbps at 44.1 kHz.
- WMA Low Quality Audio Optimized for low-bandwidth streaming scenarios. The default bit rate is 64 kbps.
If you chose a WMA profile, you can customize your profile settings by changing any of the parameters in the advanced properties section. To view advanced properties, click Show/Hide advanced properties .
By default, all the WMA profiles in the preceding list use the standard WMA codec. However, you can also choose the WMA Professional or the WMA Lossless codec. WMA Professional is the most flexible WMA codec available, and is suited for very high-quality, high-resolution playback at several bit rates. WMA Lossless is the highest-quality codec of the WMA codecs. This codec offers a bit-for-bit duplication of the original file, thereby creating a file with no loss in data from the original. This codec is ideal for compressing files for archiving.
For the other options, enter your custom settings in the appropriate category. If you are going to change the default parameters, you should be knowledgeable about what effect your changes will have on the final file. For more information, consult the Expression Encoder User Guide.
Exploring the Container section
The Container section
Another section in the Profile category is the Container section. Here, you choose the file format that you want your audio stream to be added to. If you chose a WMA profile, your only choice is ASF Single File, which means that your output will be a basic WMA file. If you chose an AAC profile, your only option is MP4 Single File. For some audio profiles, you can choose Two Pass Encoding, which means that Expression Encoder sends each frame to the codec for analysis before subsequently encoding the frame. The result is a more efficiently encoded file.
Note also that the total bit rate of the encoded file, as well as an estimate of the final file size, is displayed in the Container section. The file size estimation is especially useful to guide you when customizing your profile options, so that you remain aware of how your profile choices are affecting file size.
The final two adjustments, Min Packet Size and Max Packet Size are video settings and do not have any effect on audio-only output.
Once you set your parameters, you are ready to encode. Remember that you can encode several audio files at the same time, all using the profile that you set up. Also, if you plan on encoding more audio using the same settings, you can save this profile as a preset that you can then apply to any future encoding job.
For more information about encoding audio, consult the Expression Encoder User Guide.