Compressing a digital audio with loss is to reduce the size of an audio file.
Codecs are used to reduce the size of the files. Some of the operations that codecs can perform to reduce file sizes are as follows:
Reduce the bit rate of the original sound so that the audio takes up less space.
Remove sounds at frequencies that are not noticeable by the human ear.
Elimination of redundancies of the audio signal.
They can reduce the number of existing channels by transforming a surround sound to Stereo.
Reduce the number of bits per sample.
Etc.
Note: The compression process of an audio is extremely complex. In addition, each codec applies different methodologies to compress the size of an audio.
Obviously during the compression process there will be a loss in audio quality. The higher the weight reduction of the compressed file, the higher the loss of quality.
UTILITIES THAT YOU HAVE TO COMPRESS AN AUDIO
Obviously compressing an audio has certain utilities. Some of them are as detailed below:
The space needed to store the songs on our hard drive will be much smaller. Although hard drives are cheap and their storage capacity is large, it is not feasible and / or practical to store all of our songs without loss.
We can pass the audio files to third parties in a much more convenient and fast way. After compressing a music song we can pass it by email or other means without any problem.
It seems that the trend in the very near future will be to consume video and audio via streaming. Therefore the compression of video and audio is very important. If we offer a web service in which we provide streaming audio, it is essential to compress the audio to save bandwidth and so that customers can play it at home without problems.
Select the compressed audio file format
There are numerous types of compressed file format with loss. Some of the most popular are the following:
.mp3
.ogg
.wma
.m4a
.aac
Depending on the needs, it may be useful to select one format or another.
However in my case I recommend using the mp3 or ogg file format. The reasons are as follows:
The .mp3 files do not stand out for providing the best audio quality. However, the .mp3 format is the most universally extended.
Any music player is capable of playing the .mp3 file format. You cannot say the same of the other file formats.
Everyone is able to play audio in .mp3 format. Even people with little knowledge technologically speaking.
If someone does not want to use the .mp3 format because they think the quality is not enough, or because it is a proprietary format, I recommend using .ogg. In the following link you can find the advantages and disadvantages of the .ogg files with respect to the .mp3 files.
Select the audio compression codec (encoder)
Once the file format is selected we must be aware of the codec that we will use to perform the audio compression.
In the case that we want to compress in the .mp3 file format there are the following codecs:
FHC: It’s the first codec that existed. At present this codec has become obsolete. Its compression time is very high and does not support variable bit rate.
Xing: It is the fastest encoder and allows you to obtain files with a variable bit rate (VBR). However, the quality level offered by this type of encoder is lower than Blade and Lame.
Blade: Until Lame’s appearance was the best option. It is slightly slower than Xing, but the quality levels obtained are much better. Currently this host has a problem and it does not support variable bit rates.
Lame: It is available under the GNU license and is also the best host available today. It supports variable bit rates, is fast and the quality obtained is better than in the rest of the encoders.
