Introduction to lossless audio
Why are we talking about this topic?
The reason is that recently I got very excited to find audio in the original wav, APE, FLAC lossless format on the internet, I thought
I enjoyed a handful and the results were lackluster, much to my disappointment.
After thinking carefully, the audio in lossless wav format or even the original pcm may not be of high quality. let’s go over everything
Introduction to Lossless Audio Sample Rate
The analog audio signal is sampled to obtain discrete sample points, then quantized and finally compressed and encoded to obtain the audio material that is finally presented to us, such as wav, AAC, mp3, APE, FLAC, etc.
The denser the sample clock (sampling rate) and the higher the number of quantization bits (quantization bits), the closer this discrete curve is to an analog signal, the closer it is to the most realistic sound.
So some people will ask, why use digital signals instead of analog signals?
Very simple digital signals, the hardware cost is low, and the analog hardware cost is very high.
Also, stable, easy to handle, compress, stream. Computers can only recognize digital signals of 0 and 1.
The purpose of sampling and quantization is to obtain digital signals.
So what is compression encoding for?
For example, when boarding an airplane, a passenger’s luggage cannot exceed 100cm * 100cm * 100cm, so what should I do? Use a compressed bag to drain the air and compress the space.
Fold and destroy items, or even discard small items you don’t need, so you can get through.
Compression encoding is to save bandwidth and storage space, and the network and hard drive also have bandwidth and storage limitations.
Generally, a wav song is 50M, then the mp3 is compressed to 1/10 of the original and converted to 5M, then more songs can be placed on the hard disk and downloaded from the Internet.
some songs.
So does compression encoding destroy the content quality of the original audio material?
There are two types of compression encoding:
1. Lossy formats like mp3. This is like folding and destroying the items, or even throwing out some small items that are not used, packing them in a suitcase and compressing them.
After arriving at the destination, please decode, open the suitcase, and put all the items in the same place. At this time, some items have some minor problems and losses, but basically do not affect the use.
2. Lossless format, such as APE, FLAC, which is like compressing a quilt with dry air in a suitcase. In the end, the destination is Hou, decoding, the quilt is not damaged, it is exactly the same as the original, there is no loss.
Therefore, when conditions allow, we should use lossless formats as much as possible. The information is the same before and after compression.
So where is the problem of poor sound quality in formats like wav, APE and FLAC?
As you can see from Figure 1, the problem lies in the data before compression encoding, and the data before compression encoding is very poor, even if it is lossless.
That’s useless, it’s like the luggage you originally brought is very broken, second-hand, after zipping and unzipping, at most it can be restored.
The same as before, it will not become new.
Most of the lossless audio on the Internet is converted by the user himself, and the source of the audio is unknown. It can be converted from mp3, or it can be ripped from CD discs, etc., so
Quality cannot be guaranteed, so the discs sold are also copied from the original master tape, which is genuine.
Therefore, if you want to hear good things, you still have to pay a price, the question is whether users can accept this price.
