MP3 encoder

1. MP3 Encoder FAQ

: what is an MP3 encoder?
An MP3 encoder is a piece of software that uses the MP3 codec algorithm (compression/decompression) to create mp3 files. Most encoders only convert
a WAV file to an MP3 file, although many can convert other formats such as WMA, Real Audio, Ogg, etc.

There are only a few standalone encoders, and a lot of software also only uses 4 main encoding engines, largely due to
to Fraunhofer Gesellschaft patents and various companies helping with ISO sources. Although no company owns the license, the
Developers must pay expensive license fees no matter what proprietary MP3 encoder they use. Major MP3 encoding engines include: LAME (
non-ISO source), BladeEnc, Fraunhofer, and Real Networks’ Xing encoder.

– How does the MP3 encoder work?
The core technology under MPEG-Layer 3 is included in the MP3 encoder. The decoding process uses a series of algorithms and rules to compress audio.
The encoder also detect sounds that occur at the same time
and they try to rule out any that might be “masked” or “inaudible” by other sounds.

– What is a good MP3 encoder?
Xing is the fastest encoder in terms of speed, but the worst in quality. For smaller file sizes, Fraunhofer FastEnc
offers the best quality. LAME is a very good encoder, and one version is faster than the previous one, BladeEnc
it is the best quality for large files, but very slow.

2. Dissection of MP3 files
In addition to proficiency in using the basic features of the MP3 encoder, ordinary users do not need to know how the internal structure of the MP3 file is encoded, just like the situation when
face JPEG or DOC files. Out of morbid curiosity, here’s an X-ray view of an MP3 file:

– Box header
As mentioned above, MP3 files are made up of thousands of “frame frames”, each frame containing a part (second part) of valuable audio data.
for the decoder to reconstruct the audio data. The first part above is the box header. (Frame Header), which consists of 32-bit metadata related to the
later data, see the figure below. The MP3 header begins with an 11-bit “sync timing” block, which allows the player to seek and lock the first
legal framework available, which is useful in MP3 streaming, which can quickly move or jump ID3 from the playback source block to a normal one.
position . However, simply detecting synchronized blocks is theoretically not enough, so it is necessary to check the header.

– transmission lock
MP3 was originally designed for broadcast, and as a result it became important that the MP3 receiver could be synchronized with the signal at any part of the broadcast,
so the frame header is placed at the beginning of any frame transmission, so when an MP3 receiver “tunes” to a data stream, it picks up the
signal instantly and you can play it immediately. Interestingly, this fact makes it possible to cut MPEG files into small segments, each of which can be played independently. But unfortunately
not possible in 3-layer (MP3) files, where frames often depend on other frames, so you can’t just
Edit .

– Frames per second
Just as the movie industry has a standard for the number of frames per second in film to ensure proper viewing on any projector,
A similar standard is used in the MP3 standard, regardless of the file’s bitrate, MPEG-1 A frame in the file is 26 ms, approximately 38 fps frames per second. If the bit rate
is , the frame size is correspondingly larger, and vice versa. Also, the number of samples contained in an MP3 frame is constant, 1152 samples per frame.

The total size of any given frame can be calculated with the following formula:

FrameSize = 144 * BitRate / (SampleRate + Padding).