iTunes

Propeller

Senior Member
Jul 20, 2020
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UK
Anybody else noticed that the sound quality of files purchased on iTunes is better than everywhere else? A fuller and richer sound pretty much every time. It might be to do with Apple's patented technology. After all, they were the industry leader when digital music became popular in early 2000's. The files themselves are variable bit rate. Typically around 256 kbps. Hoping the producers and tech gurus here can shed some light on this.
 
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Motion

Member
May 18, 2021
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Actually I have also felt this, but thought nothing of it, that I might be mistaken. I made the switch from ITunes to Spotify and felt like something was off but after investigating and finding out iTunes was 256kbps I thought I must be going crazy to think my premium Spotify account would be worse at 320kbps

Have you done a thorough side by side comparison to observe?
 
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Julian Del Agranda

Elite Member
Jul 3, 2020
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iTunes doesn't sell .mp3 files, but .acc.

From wikipedia: Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves higher sound quality than MP3 encoders at the same bit rate.

So yeah, AAC is better than mp3, but worse than .wav (since .wav is lossless). But AAC still has very kind file sizes. So it's a nice extension. Only the industry has been about mp3's forever and ever, so that's still a standard music file extension for many.

I personally don't believe many people can hear much difference between those files though.

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AAC's improvements over MP3​

Advanced Audio Coding is designed to be the successor of the MPEG-1 Audio Layer 3, known as MP3 format, which was specified by ISO/IEC in 11172-3 (MPEG-1 Audio) and 13818-3 (MPEG-2 Audio).

Blind tests in the late 1990s showed that AAC demonstrated greater sound quality and transparency than MP3 for files coded at the same bit rate.[4]

Improvements include:

  • more sample rates (from 8 to 96 kHz) than MP3 (16 to 48 kHz);
  • up to 48 channels (MP3 supports up to two channels in MPEG-1 mode and up to 5.1 channels in MPEG-2 mode);
  • arbitrary bit rates and variable frame length. Standardized constant bit rate with bit reservoir;
  • higher efficiency and simpler filter bank. AAC uses a pure MDCT (modified discrete cosine transform), rather than MP3's hybrid coding (which was part MDCT and part FFT);
  • higher coding efficiency for stationary signals (AAC uses a blocksize of 1024 or 960 samples, allowing more efficient coding than MP3's 576 sample blocks);
  • higher coding accuracy for transient signals (AAC uses a blocksize of 128 or 120 samples, allowing more accurate coding than MP3's 192 sample blocks);
  • possibility to use Kaiser-Bessel derived window function to eliminate spectral leakage at the expense of widening the main lobe;
  • much better handling of audio frequencies above 16 kHz;
  • more flexible joint stereo (different methods can be used in different frequency ranges);
  • additional modules (tools) added to increase compression efficiency: TNS, backwards prediction, perceptual noise substitution (PNS), etc. These modules can be combined to constitute different encoding profiles.
Overall, the AAC format allows developers more flexibility to design codecs than MP3 does, and corrects many of the design choices made in the original MPEG-1 audio specification. This increased flexibility often leads to more concurrent encoding strategies and, as a result, to more efficient compression. This is especially true at very low bit rates where the superior stereo coding, pure MDCT, and better transform window sizes leave MP3 unable to compete.

While the MP3 format has near-universal hardware and software support, primarily because MP3 was the format of choice during the crucial first few years of widespread music file-sharing/distribution over the internet, AAC is a strong contender due to some unwavering industry support.
 

Hensmon

Admin
TranceFix Crew
Jun 27, 2020
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UK
This all makes more sense to me now. I always was hesitant to switch to Apple Music due to the stated 256kbs, but looks like it doesn’t mean lower sound quality, just more efficient compression.

Despite its issues, still love ITunes as a product and managing a real library
 

Hot Tuna

Senior Member
Aug 24, 2020
427 Posts
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142 Paul van Dyk Avenue
It depends what you are comparing to. Spotify, for example, adds its own volume control to every upload so that listeners' perceived volume remains equal across every song and genre on the service. Because trance is typically mastered 'loud', trance tracks on Spotify will be reduced in volume much more than the average song, reducing their dynamic range and your perception of the quality.

 

Propeller

Senior Member
Jul 20, 2020
687 Posts
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UK
The files I download from iTunes are actually .m4a. Bit rate varies from 242 to 300 kbps. They actually sound better than Wav. The only format I've heard that sounded better was .Aiff
 

Julian Del Agranda

Elite Member
Jul 3, 2020
1,598 Posts
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The files I download from iTunes are actually .m4a. Bit rate varies from 242 to 300 kbps. They actually sound better than Wav. The only format I've heard that sounded better was .Aiff
Oh you are right. The streams are aac, but you download m4a from iTunes Store.