A sound recording can be in many audio formats and compressed in different ways. This has a decisive impact on how the file can best be used further or how the recording quality turns out during playback.
TABLE OF CONTENTS
1 The need for audio formats
2 More codecs per audio format
3 Meaning of sample rate and bit rate
4th Compression of audio files
Lossless compression
Lossy Compression
With the mass of audio formats, the overview is quickly available. Fortunately, there are plenty of free players out there that can handle a variety of different audio formats and codecs. Anyone who comes across an unusual data format can get many decoders online for free in order to be able to play the format.
THE NEED FOR AUDIO FORMATS
With all the masses of formats, the question arises why so many of them are necessary in the first place. In the end, a single audio format cannot serve all of the intended purposes. In order for a computer to be able to work with an audio file , it must have precise specifications on how the file is to be played and read. This applies not only to audio files, but also to every other file format that is available on the computer.
The format defines the form in which the operating system must handle the data. If the computer does not have the necessary instructions to know what to do with the file, it cannot use it. With audio files, users often encounter this problem in the form of the error message “Codec not found.” This means nothing other than that the computer needs the codec to know how to handle the file. A bit like trying to put someone in a car and tell them to drive without telling them which pedal is for what. If you try to drive “on good luck” and step wildly on the various pedals, you will hardly be able to move the vehicle or stall the car. Neither does the computer without a codec know how to play the music from the file,
MORE CODECS PER AUDIO FORMAT
However, anyone who believes that each file format only needs one codec is wrong. In fact, there are different codec programs for a file format that make a difference in the files that are present. Just as we know it from any software, codecs are also continuously being developed in order to offer better sound quality. However, this quickly has the disadvantage that older codec versions no longer understand the new data formats and is one of the reasons why many media players such as the VLC player need regular updates. If you want to play many different data formats with your player, you should have as many codes as possible ready for your player. Many codecs, or at least the associated decoders, can be downloaded for free from the Internet. Codecs are often offered in packages,
MEANING OF SAMPLE RATE AND BIT RATE
The sample rate and bit rate are also decisive in the quality of audio formats. The sample rate provides information about how often the program saves the level per second. In order to achieve the quality of CD recordings, you need a sample rate of around 44,100 Hz. Conversely, this means that 44,100 values are actually stored for one second of music and thus has a direct effect on the size of the file. The higher the sample rate, the larger the amount of files that are saved.
The bit rate, on the other hand, determines the amount of data the program processes per second. Both constant and variable bit rates can occur. Similar to the sample rate, they also have an influence on the data size, but also have an influence on the sound quality of the recording.
Converting audio files to other formats can never improve the quality of a recording. The quality can only be maintained or deteriorated depending on which form of compression is used. Because every compression causes part of the audio data to be lost, even if the difference cannot always be heard by the human ear.
COMPRESSION OF AUDIO FILES
What all audio and video data have in common is that they are written compressed into files. Since the amount of data that arises can be very large, the codecs try to reduce the amount of data during coding. This is why the compressor / decompressor is often referred to as a codec. Similar to the number of file formats, there are many different compression methods here. Basically, however, a distinction can be made between lossless and lossy compression.
Lossless compression
With lossless compression, the original data is retained; it is just written more compactly in a file. In the case of images, for example, this happens in that the format does not define each individual pixel, but rather captures the differences. If there are several blue pixels that show a sky, for example, the file does not make a note of this in many mentions of “blue”, but adds up the number of pixels. Finally, there is the sum of the color, such as “76 blue pixels”.
The information content does not change, but just as “76 blue pixels” take up less space in a text document than writing “blue” 76 times in a text document, this method also reduces the file size of the audio format. In reality, however, such similarities are not always common in audio and video formats, so lossy compression is often more effective. With the lossless compression, there is always the option of restoring an original file and, if necessary, further editing it.
Lossy Compression
Lossy compression, on the other hand, reduces data in order to shrink the amount of data. The compressor tries to evaluate which data is irrelevant and to sort it out. Since parts of the original data are lost in this way, a file compressed in this way can no longer be faithfully restored. How good the recording will ultimately be depends crucially on how well the encoder can judge which data is relevant or irrelevant for the listener. In this regard, the programs’ assessments are based in part on perceptual psychology. The program sorts out signals that humans cannot perceive with eyes or ears because they overlay other signals such as louder sounds too much. This is the case, for example, in the case of temporal or simultaneous masking.
With temporal masking, a loud sound drowns out a quiet sound so that it can no longer be perceived by the listener. It therefore makes little sense to keep the quiet tone as data ballast. With simultaneous masking, two tones with very similar frequencies are played at the same time. Because of this similar frequency, the human ear cannot effectively distinguish between tones. For the most part, the average listener barely notices the differences in quality between these recordings and lossless ones. However, a trained ear can perceive differences in some cases. The greatest risk of lossy compression, however, remains the inability to restore the original data. So you no longer have the opportunity to amplify soft tones and make them audible for the audience.
