Lossless audio compression


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Lossless audio compression

Lossless Audio compression

FLAC is perhaps the most popular lossless audio format and encoding codec. Music lovers are gradually switching to this format. WavPack competes with it, but it is not that popular. It’s the same story with Apple Lossless, which reduces the size to 60%.

Lossy file compression

The story here is: quality is better and size is bigger.

Skeptics say that it is almost impossible to distinguish MP3 (320 kbps) from Losless by ear. “And if there is no difference, why pay more?” In fact, on ordinary equipment, it is quite difficult to feel the difference in audio formats, even for music lovers. But there are those who immediately feel this difference (they personally attended the experiment). But when listening to a good device, the difference is huge. The problem is that not everyone can afford a good device.

In what format and with what quality is music heard on the radio?
In fact, we can say that there are currently two main audio formats: lossy (compressed) and lossless (uncompressed). They are classified into many types.

Lossy takes up less disk space, but degrades the quality of the audio track. When compressed using the MPEG protocol (hence the name mp3 – mp4 for files containing video sequences), the hues and transition tones, which are barely noticeable to the ear, are cut off. This makes the file clearer, but it also degrades it. The last place is occupied by the bit rate of that file: the degree of compression of each second of the audio track. The lower the bitrate, the less space the file will occupy and the worse the quality. Thus, a composition of three minutes in mp3 with a bit rate of 320 kilobits per second will occupy up to 3 megabytes on disk; a similar composition with a 96 kilobit bit rate will occupy about 400 kilobytes.

Lossless is as close to the original analog sound * as possible, making it much loved by sound engineers. Lossless formats take up much more disk space even compared to mp3-320. Among these formats, the most common are WAV (standard), FLAC (economic), AIFF (Apple). The former is used most often.

Professional sound recording is done only in uncompressed format. Only with him do the sound engineers work.

On the radio, the situation is somewhat more complicated. This is due to the peculiarities of the work of the media, namely efficiency and commercial profitability. The use of high-capacity servers is expensive and therefore most radio stations encode audio tracks in mp3 format at a bit rate of 256 kilobits per second. However, this is typical mainly of national stations. Equipment purchased from abroad has standard configurations that assume WAV encoding.

Why are software developers focusing on WAV? Because the radio signal cannot propagate without interference. Therefore, the listener still receives a small and sometimes significantly distorted signal. Therefore, broadcasters are faced with a reasonable question: what quality of sound will the listener perceive best: distorted ideal or distorted distortion? For this reason, in Europe and the United States, the WAV standard (AIFF, if the station operates with Apple equipment) is adopted, in Russia – mp3 with a bit rate of 256 kilobits per second.


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Lossless audio compression explained

Lossless audio compression explained

LossLess Audio compression

FLAC is perhaps the most popular lossless audio format and encoding codec.

lossless audio compression

Music lovers are gradually switching to this format. WavPack competes with it, but it is not that popular. It’s the same story with Apple Lossless, which reduces the size to 60%.

Here the story is exactly the opposite: the quality is better and the size is greater.

Skeptics say that it is almost impossible to distinguish MP3 (320 kbps) from Losless by ear. “And if there is no difference, why pay more?” In fact, on ordinary equipment, it is quite difficult to feel the difference in audio formats, even for music lovers. But there are those who immediately feel this difference (they personally attended the experiment). But when listening to a good device, the difference is huge. The problem is that not everyone can afford a good device.

Compressed using special lossless audio codecs, it can be restored with absolute precision if desired.

If you take a normal audio CD disc with analog sound, record it in WAV format for uncompressed sound, then compress WAV using lossless codec, then decompress the resulting sound file into WAV and burn the result to a blank CD , you can get two completely identical audio files COMPACT DISCS.

The advantage of lossless for storing an audio collection is that the quality of the recordings is much higher than that of lossy codecs and they take up less space than uncompressed audio. It is true that lossy files are smaller than lossless music files. Most modern playback programs understand the lossless format. Programs that cannot play it can easily learn it using the lossless plugin. What are lossless audio formats?

Lossless audio formats
A true music lover is unlikely to be satisfied with the sound of music recorded in Ogg Vorbis or MP3 compression formats. Of course, if you listen to audio recordings on home audio equipment, sound defects cannot be heard with your ear, but if you try to play a compressed file on high-quality Hi-Fi equipment, you will immediately find the sound defects. . Of course, creating a collection of quality music on CD or vinyl is not easy. There is a reasonable alternative to this path for lovers of high-quality sound: lossless music. It can be stored on your PC in a way that allows you to keep the original music settings unchanged, even if compression is applied. In this way it simultaneously solves the problems of high-quality music and its compact storage, since audio equipment for listening (headphones, speakers, amplifiers) is quite affordable.

Uncompressed lossless audio formats:

CDDA is an audio CD standard;
WAV: Microsoft Wave;
IFF-8SVX;
IFF-16SV;
AIFF;
Compressed formats:

FLAC;
APE – Monkey’s Audio;
M4A – Apple Lossless – Apple’s high-quality music format;
WV – WavPack;
WMA: Windows Media Audio 9;
TTA – True Audio.
LPAC;
OFR – OptimFROG;
RKA-RKAU;
SHN – Shorten.
FLAC format
The most common format is the. It differs from lossy audio codecs in that no data is removed from the audio stream when it is used. This makes it possible to use it successfully to play music on Hi-Fi and Hi-End equipment, as well as to create an archive from a collection of audio recordings.

The great advantage of the format is its free distribution. This is important for musicians who record music on their own. The format has grown in popularity lately, thanks to which its support is included in the vast majority of multimedia players.

APE format
Unlike FLAC, for the APE format there are only codecs and plugins for the Windows platform. For other platforms, there are expensive third-party software solutions. The algorithm is capable of achieving lossless compression of the audio information between 1.5 and 2 times. It includes three main stages of encoding, of which only one is based on the use of inherent properties of sound for compression. The rest are similar to conventional filing cabinets. Despite the fact that the compression algorithm is distributed free of charge, the licensing restrictions are such that it is practically inaccessible for amateur musicians.

Apple Lossless Format
You can listen to high-quality lossless music using the audio compression codec without sacrificing Apple quality. This format was developed by Apple for use on its own devices. The format is compatible with iPods with special dock connectors and the latest firmware.

Compressed audio formats

Compressed audio formats

Compressed Audio File Formats

Understanding compressed audio formats
The digital age dictates its own laws, according to which, in particular, audio and video information is more convenient to store and transmit in compressed form. Let’s briefly discuss the principle of sound compression.

Compressed Audio file formats

As you know, the music we listen to consists of a set of signals, each of which has its own characteristics, including loudness. The human auditory system is designed so that we do not distinguish or misdirect a weak (low) signal from the background of a strong (strong) signal. This principle forms the basis of modern means of compression (compression) of audio data.

If we imagine that a signal of a certain length is divided into many parts, and each part is processed in such a way that a weaker signal, which is difficult to distinguish from a strong one, falls under the knife and a stronger signal remains, then this will be a rough model of audio signal compression. … Consequently, the level of data compression will depend on how many parts (samples) the original file will be divided into and how many weak signals from each individual sample will be removed (what the bit rate will be: the number of bits in a sample of a specified duration).

The first versions of codecs for data compression acted quite crudely: they just cut off a weak signal and did not take into account the type of music, therefore, rather energetic music, without special nuances, in a compressed form does not it sounded worse than the original, whereas more complex classical and acoustic music simply lost all color and depth.

As a result of this, a transition to a more intelligent compression algorithm, with a variable bit rate, was made. Depending on the musical texture, that is, the ratio of weak and strong signals, the codec changes the amount of weak signals cut, so that we hear a more believable sound.

Obviously, with a higher sample rate (sampling) of 44.1-48.0 KHz and a higher bit rate (160-192 Kbps), we will get a sound more consistent with the original than with a sample rate 22 KHz and 64 Kbps bit rate. However, the size of the final compressed file is directly proportional to the selected sample rate and bit rate, and this is what people who distribute music in the form of compressed (compressed).

It should also be remembered that most algorithms cut the upper part of the audible range as well, starting at around 15 kHz.

There are currently several original compression algorithms, most of which are compatible with Linux.

Ogg Vorbis
Ogg Vorbis is a completely open audio format that allows you to store and transmit audio information with high sound quality (44.1-48.0 kHz sample rate, 16+ bits, polyphony (multi-channel audio)) and bit rates ranging from 16 to 512 kbps per channel. The number of channels processed can be as high as 255. This allows Vorbis to be on par with MPEG-4 (AAC and TwinVQ), WMA and PAC audio, and clearly superior to MPEG-1 Layer 3 (MP3) audio. .

Ogg Vorbis is also a streaming format, allowing it to be used, for example, for Internet broadcasts, especially since this format is compatible with Icecast. The characteristics of the codec algorithm allow you to get the final file smaller than MP3 files of similar quality.

For the reproduction the console program ogg123 is used, to encode – oggenc; both have graphic housings. More details on both are in the following sections.

MP3
MP3 or MPEG-1 audio layer 3 is by far the most popular format for storing and transmitting compressed data. This format was developed by the Frauenhofer Institut, Germany. However, despite the ubiquity of the format, it should not be forgotten that the patent for MP3 encoding and decoding algorithms belongs to a single company, so the end user at any time may find themselves in a very disadvantageous environment, such as It has already happened with the developers of free MP3 data compression tools …. You can get details about the license conditions on the developers website.

WMA
The WMA format is a proprietary product of Microsoft. It failed to occupy a market segment comparable to MP3, but it has some popularity despite serious security concerns identified. At the moment, only the universal MPlayer player can play WMA files. There are no free data compression tools for this algorithm and its appearance is unlikely.

Lossless audio formats

Lossless audio formats

Lossless audio

Audio files can be converted in a more or less space saving way using lossless or lossy codecs. While the data reduction is absolutely true to the original with lossless codecs, a difference can be heard from the original material, especially with heavy compression with lossy codecs.

Lossless compressed audio files lose approximately 25% to 50% of their original file size. Typical representatives are Monkey’s Audio, FLAC, or WavPack. Modern lossy codecs like AAC, Ogg Vorbis, or MP3, on the other hand, reduce source material by 90% without sounding noticeably worse.

Lossless audio compression

Unlike documents or images, for example, audio files are very difficult to compress, since identical repetitions are very rare in music. But it is precisely on such occurrences that the Huffmann or Lempel-Ziv algorithms depend, which are used in ZIP or RAR, for example. Therefore, most non-clustered compressors employ predictive coding. The signal is divided into a music component and a noise component. Depending on how well this prediction has been made, the noise component should ideally be Gaussian white noise that can be easily compressed using conventional methods.
In the ideal case, the result is 50% compression, which is highly dependent on the piece of music.

Monkey’s Audio, FLAC and WavPack are popular formats for lossless compression of WAV (PCM) files, for example digitized original recordings from the recording studio (for archiving or later processing) or archiving copies of music CDs. The sound quality is always the same as the original and the checksums reveal corrupted files. Increasing hard drive capacity at affordable prices makes “Lossless Codecs” interesting for everyday use.

Uncompressed: WAV (PCM)

WAV is the largest common denominator of Windows audio formats. The Macintosh equivalent is called AIFF. WAV is actually the collective term for various subformats, of which PCM is the most common and is generally equated with WAV.

WAV (PCM) is an uncompressed recording of sound samples: the time signal of a noise is sampled, quantized, digitized, and saved at discrete points in time. The more often and finer you record these values, the better the sound. With CD quality music, this instantaneous value is recorded 44,100 times per second and recorded with 16-bit “precision”, that is, 2 ^ 16 = 65536 possible values.

With the help of special programs (eg CDex, EAC, Audiograbber), Audio CDs can be transferred to the hard disk as WAV (PCM) files. Viewed in this way, WAV (PCM) files are copies of the original, provided the CD-ROM drive is not read incorrectly or the CD is damaged. One minute at CD quality requires roughly 10MB of storage space, which is not as happy to give away even in the age of ever-larger hard drives.

On the PC, WAV (PCM) and CD-quality (44.1 kHz, 16-bit, stereo) audio files are often the starting material for creating space-saving audio files in formats such as MP3. However, for sound processing on the home PC, WAV (PCM) is the first choice.

Monkey’s Audio

Monkey’s Audio is a lossless audio codec for PCM wave files. Monkey’s Audio comes with a convenient program interface (in English), over which files can be compressed, decompressed, verified or tagged. PCM wave files (any sample rate, 8/16/24 bit, mono or stereo) or corresponding Shorten or WavPack files are accepted as source files. Monkey’s Audio does not support multiple channels.

The APE tags that are used to store the title information can be supplemented with their own fields and are therefore very flexible. They are now used in conjunction with other audio formats as well.

The included command line encoder allows integration into other programs. Various audio players support the format through plugins. A plug-in for Winamp can be installed at the same time as installation. Monkey’s Audio is a Windows program by default. However, there is a platform independent version of Java.

FLAC

FLAC stands for “Free Lossless Audio Codec”. There are several lossless audio codecs available. FLAC is suitable here for several reasons: FLAC follows the open source philosophy (free open source code, available for many operating systems), works very fast, has a good and secure framework structure.