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MP3

 

MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is a patented digital audio encoding format using a form of lossy data compression. It is a common audio format for consumer audio storage, as well as a de facto standard of digital audio compression for the transfer and playback of music on digital audio players.

 

Sample Rate
Pro Audio Converter will automatically choose the best sample rate for the job. If you have a special reason and need a specific MP3 sample rate, you can choose from any of the sample rates that the MP3 specification allows for.

 

Bitrate Mode
Constant Bitrate (CBR) - This is the default encoding mode, and also the most basic. In this mode, the bitrate will be the same for the whole file. It means that each part of your mp3 file will be using the same number of bits. Whether the musical passage is a difficult one to encode or an easy one, the encoder will use the same bitrate, so the quality of your mp3 is variable. Complex parts will be of a lower quality than the easiest ones. The main advantage is that the final files size won't change and can be accurately predicted.

Variable Bit Rate (VBR) – In this mode, you choose the desired quality on a scale going from 1 (lowest quality/highest distortion) to 10 (highest quality/lowest distortion). The encoder tries to maintain the given quality in the whole file by choosing the optimal number of bits to spend for each part of your music. The main advantage is that you are able to specify the quality level that you want to reach, but the inconvenient is that the final file size is totally unpredictable.

Average Bit Rate (ABR) – In this mode, you choose a target bitrate and the encoder will try to constantly maintain an average bitrate while using higher bitrates for the parts of your music that need more bits. The result will be of higher quality than CBR encoding while the average file size will remain predictable, so this mode is highly recommended over CBR.

 

Bitrate
When used with CBR, it is the constant bitrate to use. Higher bitrates result in higher quality audio, but larger file sizes. When used with ABR, it is the average bitrate to be used, allowing for frames of different sizes.

 

VBR Quality
Specifies the value of VBR quality. VBR quality ranges on a scale of 1 to 10 with 1 being the lowest quality and 10 being the highest. On typical music you can expect a VBR Quality of 5 to result in files averaging 132kbps, 8 averaging 200kbps.

 

Quality
This specifies the quality of the encoder algorithm. Bitrate is of course the main influence on quality, but for any given bitrate we have a choice of algorithms to determine the best scalefactors and huffman encoding (noise shaping).

Stereo Mode
Auto - Stereo or Joint Stereo (mid/side stereo) will be chosen on a frame-by-frame basis for stereo source files. In mid/side stereo, the mid (L+R) and side (L-R) channels are encoded, and more bits are allocated to the mid channel than the side channel. This will effectively increase the bandwidth for frames that do not have too much stereo separation, resulting in an overall higher quality file. Mono will be chosen for mono source files. This setting is recommended for the highest quality.

Stereo - Left and Right are encoded as their own separate channel.

Joint Stereo - Forces Mid/Side encoding for every frame.

Mono - If the source file is stereo, the two channels will be averaged into a mono signal. Mono source files will be encoded as mono.