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Chapter 4. FORMATS > Audio file formats

4.5. Audio file formats

Not to be outdone by the myriad of image formats, the audio people have been busy devising ways to compress the largest amount of audio information into the smallest possible digital file as well. One of the first formats was .wav, or wavelength-encoding, which stored the voltage value (8 or 16 bits number) at some sample rate. Blender supports .wav files sampled at 44.1 kHz or 48 kHz. The 8-bit mono format at 44.1 kHz is 352 Kbps, which represents the bandwidth needed to play the file without any pauses or gaps. The 16-bit stereo format is four times that, which may become a pipe hog.

To overcome the problems with .wav files, some wizards borrowed run-length encoding (RLE) schemes from the JPEG in connection with the motion picture industry—the, yes, you guessed it—Motion Picture Experts Group (MPEG). This group's first specification, MPEG-1, laid out how to encode audio and video. The first version of the audio specification was not that good, the second better, and the third time was the charm. This is the MPEG-1 Audio Layer 3 standard, or MP3 for short. The MP3 standard caught on like wildfire and is the most commonly used audio compression scheme. While some quality is lost, you have a wide array of compression choices, some of which (depending on the kind of audio) result in a very small file size. Small file sizes therefore need much less transmission pipe (bandwidth) to be transmitted or stored on the playback device. A fairly simple decompression algorithm makes it very easy to reexpand and play the audio track back to the consumer. I have had good success using the MP2 and MP3 audio encoders inside a MOV container. In Blender, you set the audio codec on the Audio panel, which is revealed when you choose the FFmpeg format.


  

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