What is Sound?
We highly recommend you read A Digital Audio Primer if you want to learn more about digital audio. It is a short primer on the subject and will help you understand the basic properties of sound and provide basic information on various aspects of sound quality and compression techniques.
File Formats Supported by recorder.xhead
recorder.xhead is based on Apple's QuickTime technology and as a result supports the sound file types supported by Quicktime. recorder.xhead can play a wide variety of file types and save sounds in numerous file formats as well.
You cannot save directly to .mp3, but you can convert any sound file to .mp3 afterwards by choosing Utilities / Convert to .mp3. Here's a breakdown of the file types you can save your recordings in as they appear in the recorder.xhead / QuickTime save file dialog panel:
Movie to 3G - .3gp / .3g2
.3gp is a new worldwide standard for the delivery of audio over third generation (3G) cellular networks. It is based on MPEG-4. 3GPP was created for use on the Global System for Mobile Communication (GSM) networks, which is the most popular type of 3G network around the world. the 3GPP2 was defined by a different group of telecommunications bodies called 3rd Generation Partnership Project 2 (3GPP2) for use on the second most popular type of 3G network, Code Division Multiple Access (CDMA) 2000. The 3GPP and 3GPP2 formats are very similiar and both based on the QuickTime file format and contain MPEG-4 and H.263 video, AAC and AMR audio, and 3G text. 3GPP2 adds the option to use QualComm PureVoice (QCELP) audio and Movie Fragments, a technology that allows multimedia content to be delivered incrementally over standard TCP wireless networks, providing a more immediate viewing experience for the end user.
Movie to AVI - .avi
.avi is Microsoft's first video format. Header information is placed at the end of the file. The codec support is limited.
Movie to Hinted Movie - .mov
A hinted .mov file is one that is intended for streaming over networks. The .mov contains a hint track, which contains information on how the server should package the media for the network. You can find more information on preparing movies for streaming here.
Movie to MPEG-4 - .mp4/aac
The standard Audio codec referred to .mp4 is Advanced Audio Codec (AAC). The sound quality is much better than .mp3 at lower bitrates. You can find out more about .mp4 from the MPEG Industry Forum.
Movie to Quicktime Media Link - .qtl
.qtl stands for Quicktime media link and is an XML file type of "application/x-quicktime-media-link".
Movie to Quicktime Movie - .mov
.mov is Apple's QuickTime Audio/Video format. It has support for a variety of features such as multiple audio/video streams, sprite tracks, header information at the beginning of the file, annotations, text tracks and support for hundreds of codecs. It's also the basis for the .mp4 format.
Sound to AIFF - .aif
Apple's Audio Interchange File Format is normally used for uncompressed Pulse Coding Modulation (PCM) audio at various depths and sampling rates and supports simple codecs.
Sound to System 7 Sound - .sfil
An older sound format developed by Apple. A .sfil file is a system sound file that contains a .snd resource. You could play the sound by double clicking it in the Finder. This is pretty old school.
Sound to Wave - .wav
Microsoft wave format. This is the primary audio format in Windows. It normally contains uncompressed Pulse Coding Modulation (PCM) audio. This is the type of audio found on CDs and DVDs and is produced by audio digitizers.
Sound to uLaw - .au
.au was a file format originally developed by Sun. It is not widely used outside of the Unix community.
Sound Compressors (Audio Codecs)
Sound compressors are algorithms that compress the file size of a sound, while trading off some of the sound quality. Some compressors work much better than others. Here are a few compressors that you have an option of choosing depending on the file type you are trying to save the sound as. Just because something is supported, does not always mean it is reacommended. Compressors not recommended are noted as such.
24-bit Integer / 32-bit Integer
This codec will increase the sample size to either 24 or 32 bits.
32-bit Floating Point / 64-bit Floating Point
This codec will increas the sample size of the audio to either 32-bits or 64-bits.
ALaw 2:1
Internet standard for compressed audio in Europe and everywhere else except the US and Japan. Low compression ratio and low quality, not recommended.
IMA 4:1 / IMA ADPCM 4:1
This codec is pretty good for music and audio content. Compression is fairly low.
MACE 3:1 / MACE 6:1
Macintosh Audio Compression and Expansion (MACE). These codecs are outdated and not recommended.
QDesign Music 2
Good for music content, very high compression and a good choice for streaming.
Qualcomm PureVoice
Great for voice content, very high compression ratio and good for streaming.
uLaw 2:1
Internet standard for compressed audio in the US and Japan. Low compression ration and low quality. This sucks, not recommended.
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