AAC vs. MP4: A Comparison

In this article, we will look at AAC versus MP4 encoded formats and discuss what they are, their strengths, limitations, and how you can make the best choice when importing songs into your device.

Both AAC and MP4 are related to MPEG. AAC is MPEG-4 Part 3 and MP4 is MPEG-4 Part 14. However, MP4  is the container that stores data; that data is encoded in AAC. The container does not affect the quality of the data and is not an encoding format, so AAC cannot be compared with MP4 in this way. Quality depends on the encoder, not the file type. In other words, MP4 can use the AAC codec or others like AC3, ALS, SLS, or MP3.

Read on to learn more. 

What is AAC?

AAC file format is one of Apple’s several proprietary audio file formats. AAC stands for Advanced Audio Coding. AAC was developed in 1991 by the Moving Picture Experts Group (MPEG) as part of its MPEG-2 standardization process.

The “Advanced” refers not to the capabilities of AAC but rather to its development status at the time. A new audio format was needed to support more than just mono or stereo sound and avoid issues with storage limitations.

At this point, MPEG already had MTS (Multi-Track Single), which addressed these problems but only for professional applications since it required special hardware.

What is MP4?

MPEG-4 is a standard from the Moving Picture Experts Group for compressing video and audio data. It became widely used in recent years due to its ability to compress video files more than older standards while also supporting more features such as encoding for high-definition TV.

What makes the MP4 specification so unique is that it does not define standards for compression itself but rather provides a framework in which various encoders can be used and leaves room for multiple decoder implementations.

This means that there can be many different implementations of an MP4 audio decoder, and each performance would produce the same results.

Why Use AAC?

This file type is unique because it has the best of both worlds compared with MP3s. On the one hand, AAC sounds better than MP3 when at high bitrates.

Furthermore, an AAC stream will consume less bandwidth than the stream encoded as an equivalent 320kbps MP3 file over traditional internet connections like dial-up modems, DSL, cable modems, etc.

This is important for streaming music services and for VOIP/Skype or video conferencing software, which usually uses low-compression codecs to save network bandwidth.

Although AAC can achieve better quality than MP3s, you cannot encode an AAC file at a bitrate lower than 128kbps, so this format isn’t suitable for streaming lossless audio or archiving.

Why Use MP4?

The MP4 file format is used to store and playback video and audio content without any additional software. This is a standard feature for many of the most popular file formats used today. An example would be SWF (shockwave flash), typically found as .flv files.

MP4 files can be viewed on various devices, including smartphones & tablets, blu ray players/DVD players, gaming consoles such as the Xbox360 and Playstation 3, Apple devices such as Ipod’s and iPads, etc.

This means that a single media player application can be utilized to playback multimedia content across many devices. You certainly couldn’t say that about all available multimedia file formats, even though some work across multiple devices.

Advantages of AAC

• Smaller File Sizes – AAC files typically have about half the size of an equivalent quality level in a standard MP3 or WMA encoding. Their small size comes mainly through several different compression techniques implemented in the AAC algorithm.

• Improved Encoding Capability at Low Bit Rates – The new AAC format uses a hierarchy of low-bit-rate encoding modes to enhance the MP3 format’s capability at lower quality levels.

• Better Multichannel Support – AAC files can be encoded with as many as 48 separate channels, far more than most other file formats such as WMA, OGG, and even MP3. This allows for better surround sound reproduction in music files.

• Better Audio Quality – Although the sample rate and bit depth of AAC is typically lower than that of WMA or other lossless formats, the compression technique applied to encode AAC preserves more original audio than formats that use linear prediction encoding like MP3.

Disadvantages of AAC

• AAC files are less compatible than MP3 files
• AAC uses more storage compared to other formats

Advantages of MP4

• Better quality – The first reason you should consider using MP4 files for your file storage and transfer needs is that these offer better quality.
• Low storage space – You should opt for MP4 files because they take up less in terms of length.
• Easy sharing and streaming – The next thing about this format is its ease of use. You don’t need anything apart from an Internet connection to watch or share these videos.
• Compatibility – This format is compatible across all devices. You don’t need to install any special software when using these files on different devices.

Disadvantages of MP4

The first disadvantage of MP4 is that it doesn’t support subtitles. This might not seem like a big deal right now.

This is because technological advancements have allowed people to watch movies with the sound on without being distracted while doing other tasks, but that will become a problem in the near future.

The second disadvantage of MP4 is that it doesn’t support a high enough frame rate to portray a 3D video accurately. This is because the technology for this was only invented in recent years. Even then, most people didn’t have access to 3D movies or TVs until 2014, when significant manufacturers began releasing them.

Similarities Between AAC and MP4

1. Both are compressed formats developed by Apple Inc. It is possible to play MP4 files on the iPod, iPad, or iPhone. However, you need special software like iTunes or QuickTime.

2. Both formats are used to encode audio data. For example, M4A is an audio-only format containing other data types such as lyrics and chapter markers. AAC is also able to carry metadata along with the actual audio content.

It is usually used for music but can also be applied where speech or sound effects are required. Each format has different capabilities for handling these additional types of data.

3. They both support stereo effects. Usually, MP4s do not use any other surround sound coding technology to increase their file size significantly.

However, AAC files can use Dolby Pro Logic and MPEG surrounds coding technology to add multiple channels to the file. This allows the MP4s to output surround sound while maintaining a small size.

Differences between AAC and MP4

1. Compatibility: The first difference we analyzed was compatibility with different devices and operating systems. As a general rule, an AAC file will work on all Apple products (iPhone, iPod, iPad, etc.) while an MP4 will not.

2. File Size: The second difference we investigated was file size. When comparing the same song in both formats, an MP4 will give you a smaller file size than an AAC which means it takes up less storage space on your device.

3. Quality: Finally, we analyzed the sound quality between the two formats. Our ears cannot detect the difference between the two files at lower bitrates (128 kbps), but as you play around with different types of AAC and MP4 files, you will notice sound quality differences between higher bitrates (192 kbps – 320 kbps).

Which is Better?

These codecs are typically used for music distribution on digital stores such as iTunes or Spotify. Both of them will be good enough to store your songs, but generally speaking, MP4 is better than AAC in most cases when it comes to quality.

Conclusion

It is challenging to compare AAC and MP4 file formats because they serve different purposes. The MPEG team developed the AAC format for encoding audio-only, while MP4 is a generic container format that can be used for storing any data.

Both are efficient in encoding quality music files, but there are still a few differences between them, making a choice even more difficult.