Best Audio Format for Your Video
What are audio formats? Which is the best one? How do I choose? And why are there so many of them, anyway? These are all valid and frequently-asked questions, but they essentially boil down to one concept: compression.
Since the start of the digital age, there has been an inherent need to download, transfer, broadcast, share and store files of various shapes and sizes.
To ease the pressure on dwindling HD capacity, compression was quickly established and has remained as the go-to method for making files smaller and thus more manageable in facilitating these activities.
Audio files are no exception to this process and, as the late 90’s explosion of (controversially) rampant peer to peer sharing of mp3s clearly illustrated, there are many clear advantages to this type of downsizing.
We may all now be familiar and comfortable with the mp3 but there is actually a plethora of different format standards that lie beyond. They vary according to the amount of compression they undergo and what sort of quality they are able to retain.
This article will explore and compare their different characteristics and help you determine which one works best for you.
What is ‘audio file format’ in multimedia?
The term audio file format can refer to any kind of file that is able to store digital audio data on a computer system. Digital audio is digital information. This information can be dense or sparse, high-quality or low. Accordingly, the bitrate is the term used to describe the amount of data (over time) that is being transferred into audio. The bit layout of audio data (excluding its metadata) is called the audio coding format and this can be either uncompressed or compressed in order to reduce the file size.
What are the different types of audio formats?
Any kind of sound is made of waves and audio files are the representation of these waves. The way those waves are encoded in audio files, through individual samples, includes the waveform’s shape at a given moment and how far away it is from the zero point.
Zero point is basically silence and audio files measure each sound’s distance from this silence – essentially a snapshot of the wave.
These snapshots can differ greatly. Just like photo images vary in quality and clarity, types of audio files vary according to their size and how much information they contain. While there are some notable exceptions, uncompressed files contain the highest amount of information and, unsurprisingly, have a higher bitrate. Compressed, lossy files generally have the least amount of information and therefore a lower bitrate.
As we stated above, understanding compression is key to being able to distinguish and categorize the many different formats in existence. The three categories all audio files can broadly be grouped into are: uncompressed, compressed (lossless) and compressed (lossy). Again, the main difference comes down to how compressed the data is (if at all) and, as a result, how much quality or “loss” you experience, as a listener.
If no compression algorithm (or codec) has been used, two things are bound to happen: zero loss in sound quality and, given enough time, a “startup disk full” warning on your computer. Essentially, an uncompressed track is a faithful reproduction of the original audio file, where real-world signal is transformed into digital audio. These audio files are very large and include all of the possible information that audio equipment can detect. As a result, while uncompressed audio files tend to be the most accurate, they do take up a LOT of disk space – about 34 MB per minute for 24-bit 96KHz stereo. Uncompressed file formats include WAV, AIFF and PCM (more on this later).
Compressed lossless files take up slightly less space than an uncompressed file, and (ideally) present few compromises where audio quality is concerned. They work by compartmentalizing redundant or repeated data and providing an “instruction set” for how they are to be recreated during playback. As a result, they can achieve a size <70 percent smaller than their uncompressed counterpart, while offering near identical sonic quality as no information is lost. An example often used to illustrate lossless encoding is a .zip file. Although a zip file is smaller than the files it is comprised of, when unzipped all files retain their original information. Common examples include FLAC, WMA and ALAC.
Compressed files remove information that is not entirely essential, thus managing to be the smallest of file formats. Lossy compression means sacrificing sound quality and audio fidelity for those smaller file sizes. During the process, some data is lost – essentially through recognizing information that isn’t perceivable by most listeners and then deleting it. These formats are a great option for streaming, or any online service in which speed of service is more important than the quality of audio. The quality of lossy files range greatly, from almost indiscernible to highly compressed files with noticeable aliasing, quantization distortion, and an attenuated high frequency range.
By far the most common audio format is the MP3. MP3 files are convenient for storing music on various devices, working on almost all playback platforms. The bit-rate at which they are recorded is crucial for the sound quality. MP3s encoded at 128kbps, for example, will incur more sound loss than those encoded at 320kbps (kilobits per second, where each “bit” is essentially a “piece” of the song).
What are the most common audio file formats?
While we are all probably familiar with the ubiquitous MP3, what about formats such as AAC, FLAC, OGG, or WMA? Why so many of them and what sets them apart? Which ones are important and which ones can you ignore? As we’ve seen above, many of these questions can be answered once you separate audio formats into the three major categories. Read on to learn about the most common formats and what their pros and cons are.
.MP3
MP3 stands for MPEG-1 Audio Layer 3. This format was released back in 1993 and almost instantly exploded in popularity – eventually becoming the most widely used format for music files. MP3s feature lossy compression, which means their quality will degrade over subsequent edits. They achieve this compression by dropping all sound data that exists beyond the hearing range of typical people, reducing the quality of sounds that aren’t easy to hear and, finally, compressing all other audio data as efficiently as possible.
For all their pioneering compression technology, MP3s are still relatively large in size – when compared to other audio file formats on our list. They can be encoded at a constant or variable bit rate. Constant bit rates ensure the same quality throughout the file but result in higher file size. Variable bit rates lower the quality during silent moments in the file, achieving a smaller overall size.
Almost every digital device with audio playback can read and play MP3 files, whether it be a PC, Mac, Android, iPhone, Smart TV, etc.
.M4A
The .M4A is an Apple-based format that corresponds to .MPEG-4 video files. They feature lossless compression, allowing for multiple edits without a loss of quality. Compared to many of the other formats on this list, .M4A files have a similar sonic quality but are smaller in size. They are responsible for playing audio on Apple products such as iPhones and iPads.
.AAC
AAC stands for Advanced Audio Coding. Developed in 1997 and intended as the successor to the MP3, it achieved moderate success due to its higher quality (and similar size), but never really overtook it in terms of popularity. Like MP3s, AAC files are also lossy audio files.
Similarly to MP3s, they can also be created with a variable or constant bit rate. The compression algorithm they use is much more advanced and technical than that of the MP3, so comparing the same recording in MP3 and AAC formats (at the same bitrates), will highlight the AACs superior sound quality.
Even though MP3s are a household name, the AAC format is widely used. In fact, it’s the standard compression method used by YouTube, Android, iOS, iTunes and multiple gaming consoles.
.OGA, .OGG
.OGA files are similar to .AAC, are open-source and utilize lossy compression. They use a variable bit rate to reduce size but this doesn’t detract from the overall sound quality. Actually, .OGA files tend to be higher in quality than MP3s although they aren’t supported by many programs – especially compared to the other aforementioned formats.
You may have also come across the OGG format which – you might be surprised to know – doesn’t stand for anything. Actually, it’s not even a compression format. In essence, it is a multimedia container capable of holding all kinds of compression formats, but is most commonly used to hold Vorbis files. Vorbis was first released in the early 2000s and grew in popularity mainly due to its adherence to the principles of open source software and its comparative performance in lossy compression.
Unsurprisingly, MP3s and AACs have such strong footholds that OGG has struggled to break into the mainstream and the fact that not many devices support it natively, doesn’t help matters further.
.FLAC
Yet another lossless format, similar to the M4A, is the FLAC. Unlike M4A, however, FLAC is open source and utilizes a hyper-efficient compression algorithm, which reduces size by 50-70%. FLAC stands for Free Lossless Audio Codec and is mostly popular among audiophiles who want to store their collections in their highest quality form. Because it is open source, it is compatible with many devices and programs.
An additional benefit is that it is (also) open-source and royalty-free, so it doesn’t impose any intellectual property constraints. Many consider FLAC to be the best audio format.
WMA
WMA stands for Windows Media Audio and is a lossy compression format. Confusingly, there’s a lossless alternative called WMA Lossless that uses the same extension, which makes it worth mentioning here.
Compared to FLAC and ALAC, WMA Lossless is the lowest performer, in terms of compression efficiency. It’s a proprietary format so poses challenges for fans of open-source software, but supported natively on both Windows and Mac systems.
Possibly the biggest issue with WMA Lossless is the limited hardware support.
ALAC
ALAC stands for Apple Lossless Audio Codec which was originally developed and launched as a proprietary format but eventually became open-source and royalty-free. It is also referred to as Apple Lossless.
While ALAC is a decent performer, it’s slightly less efficient than FLAC when it comes to compression. Unfortunately for Apple users, iTunes and iOS only provide native support for ALAC but no support at all for FLAC.
.PCM, .WAV, .AIFF
PCM stands for Pulse-Code Modulation, which is a digital representation of raw analog audio signals. As we discussed, sounds exist as waveforms, so converting into digital bits requires the sound to be sampled and recorded at certain intervals (or pulses). This format uses a “sampling rate” which defines how often the original audio has been sampled, and a “bit depth” which defines how many bits are used to define each sample. This makes the digital recording a close-to-exact representation of the analog sound.
.WAV, or Waveform Audio File Format is used as a wrapper format to store this PCM format audio, making it suitable for Windows-based computers. AIFF, or Audio Interchange File Format, exactly like WAV, is commonly used as a wrapper format to store PCM format audio for computers running iOS on Macs.
What is the best audio format?
Although this article’s focus is on technical factors to determine what the best audio format is, personal preferences also go a long way in making a choice. It’s important to keep in mind the operating system you’re working on, how much storage space you have, and how you’d like to be perceived when exporting and sending files.
Choosing a format depends entirely on what you plan on using the audio for. Ideally, you should choose one that achieves the desired level of audio quality – but nothing more. Unnecessarily high-quality audio files are difficult to move, share, convert, and manage. On the other hand, although it’s nice to save storage space, it should never come at the expense of audio quality, or your professional image.
Some hypothetical scenarios that reflect the above guidelines are:
- If you are an (audio) professional and planning to edit the audio (for a podcast, for example), then opt for an uncompressed format. This ensures you maintain the audio’s quality every time you edit and save.
- An audiophile planning to listen to his or her music collection in hi-fidelity, should choose a format that uses lossless audio compression. This will take up less storage than an uncompressed format, but still maintain the high quality of the original recording.
- If you are not concerned with perfect audio quality, For those who wish to share files on the Web, or need to consider disk space and not perfect audio quality, a format that uses lossy audio compression is the better choice. Lossy compression has become so good in recent years that most people can’t tell the difference between lossy and lossless compression anymore.
What is the standard audio format for videos?
High-quality video content should start with the best possible source material. Creators always carefully consider their video file formats, pore over the quality of their graphics, and check frame rates so that they are in good stead to create an excellent final production. They are aware of problems that can (and will) occur when using sub-standard material. Of course, there are always software solutions to improve the quality of such imperfections but the safest option is, to begin with great material.
This principle carries over to audio and it is highly recommended to begin with lossless, uncompressed WAV or AIFF files. Compressed audio lowers the quality of the final product and also creates serious problems during production. MP3 files, for example, omit certain parts of the data and can cause editing issues. Depending on the method of compression, MP3s may not be easily compatible by editing software such as Adobe Premiere or Final Cut Pro. Unfortunately, this leads to unwanted effects like audio drift and can introduce clicks and pops into your audio mix.
Other things to consider when working with audio, such as bitrate and sample rate. For all practical purposes, starting with either WAV or AIFF will go a long way to make sure you are starting with the highest quality audio possible.
Remember, when purchasing or downloading music for your video from any production library, always make sure you download the WAV/AIFF versions!
Which video format has best audio quality?
Right off the bat, you should remember that there are two primary factors that determine the quality of video format. Video files tend to be quite large and, as video resolutions continue to increase, their file sizes only grow. The format you choose plays a huge role in determining the final size of your video file.
Additionally, videos include different parts that merge into the final package. Apart from the actual video itself, the container houses the audio streams and additional information such as subtitles, metadata, menu structures and other components that all work together.
The final format considers both of these factors. First, there’s a codec, which compresses and decompresses your video and also a container that bundles everything together, ensuring compatibility with whatever video player you’re using. Thus, the codec plus the container equals the video file format.
Contrary to what you might think, video containers such as AVI, MOV, FLV or WMV have virtually nothing to do with audio quality. As we’ve mentioned, audio quality is determined by the bitrate in the audio portion of the video file. That audio portion is then multiplexed with the video to create the video file. It’s the reason why web searches for “best audio quality for video” focus on fundamentals such as audio recording, mixing, editing, restoration and not video formats.
As a sidenote, there are instances where changes in audio quality occur. For example, when changing the frame rate without demultiplexing (removing) the audio from the video. However, this degeneration in quality is not due to any format or codec – it is a matter of the audio being resampled in order to match playing time.
