Difference between audio formats Part 2
Lossless compression: FLAC, ALAC, WMA Lossless
FLAC lossless compression
Lossless compression codecs are compressed while preserving the original data.
At the time of playback, it will be unzipped → it will be played in the original uncompressed format, so
The sound quality is the same as that of uncompressed sound sources (WAV, AIFF, etc.).
However, the data capacity is half that of uncompressed.
Lossless sound sources are FLAC, ALAC, WMA Lossless …
There is not a big difference in compression ratio and since it is lossless, the sound quality does not change.
Therefore compatibility (compatible terminals and amount of compatible software) is of the utmost importance.
Among lossless compression codecs
The most important is FLAC (Free Lossless Audio Codec).
It is often handled by high resolution audio sources and there are many supported playback devices.
ALAC (Apple Lossless)
As the name implies, a lossless codec made by Apple.
I can also select it when ripping an iTunes CD,
In many cases, you can only play with Apple products.
However, iTunes does not support FLAC, so
If you want lossless compression, you must use ALAC.
Both FLAC and ALAC are lossless compression, so
If the playback device is not supported, re-unzip (WAV, AIFF, etc.),
It is possible to convert from there to the corresponding lossy (mp3, AAC, etc.) and use it.
That is why all CD sound sources are converted from iTunes to ALAC and saved and managed.
→ Import music CDs with high sound quality to iTunes. Optimal reading settings for PC sound source management.
There’s also TAK and WMA Lossless, but …
I don’t think there is any reason to use it in mainstream FLAC and ALAC.
Sound quality = sample rate x number of quantization bits
When digitizing analog voice with high sound quality,
The “sample rate” and the “number of quantization bits” are involved.
For analog to digital (AD conversion),
It requires two processes, sampling and quantification.
These two are important in terms of faithfully converting sound into data.
The CD is 44.1 kHz and 16 bit. What does this mean?
kHz: sample rate (sample rate)
Sampling rate
The sampling frequency (Hz) is
Displays the number of sampling times (sampling) per second.
The higher the number, the more times it will be processed.
If the sample rate value is just high,
The amount of sound information increases and the sound is faithfully reproduced → the sound quality improves.
The sampling frequency is also related to the frequency of the sound (treble, bass).
According to the sampling theorem (sampling theorem)
The frequency of the sound that can be reproduced is half the sampling frequency (Nyquist frequency).
Regarding the frequency (Hz) of the sound, the bass has a small amount of vibrations and a low frequency value.
On the contrary, the treble has a lot of vibrations and a high frequency value, so
The higher the sampling frequency, the higher the treble can be reproduced.
The 44.1 kHz of the CD is sampled (converted to data) 44,100 times per second.
It can reproduce frequencies up to 22,050 Hz.
By the way, the frequency that humans can recognize is generally 20-20,000 Hz.
