Can SD cards hold audio files?
What are SD Cards?
SD cards, which stands for Secure Digital cards, are a type of non-volatile memory card used for storage in portable devices. They were first introduced in 1999 by the SD Association, a joint effort between Panasonic, Toshiba and SanDisk (MicroSD Cards).
SD cards are now one of the most common types of removable flash memory cards used in digital cameras, camcorders, tablets, media players and more. They are also available in smaller sizes like miniSD and microSD cards. SD cards provide a compact and affordable way to store photos, videos, music and other data.
SD cards use flash memory, which retains data without any power source. They come in different capacities ranging from a few gigabytes to terabytes. Common SD card speeds and classes include SDHC for fast performance and SDXC for extra storage space.
Types of SD Cards
There are several different types of SD cards that vary based on their storage capacity and speed:
SD – The original SD card format had a maximum capacity of 2GB. SD cards offered slower transfer speeds compared to newer versions.[1]
SDHC (Secure Digital High Capacity) – These cards range from 4GB up to 32GB in capacity. SDHC introduced faster transfer speeds over standard SD cards.[2]
SDXC (Secure Digital Extended Capacity) – SDXC cards have capacities ranging from 64GB up to 2TB. They utilize even faster transfer speeds.[3]
The SD card formats build on top of each other, so SDHC and SDXC cards retain backwards compatibility with devices that only support the standard SD format. Each subsequent SD format offers greater storage capacity and faster data transfer speeds.
Most new devices today support SDHC or SDXC, allowing them to take advantage of the larger storage capacity and faster speeds for transferring data like audio files.
Audio File Formats
There are many audio file formats used for storing audio data, but some of the most common include:
MP3 – This is the most popular digital audio format. MP3 files use lossy compression, which reduces file size by removing some audio data while trying to minimize the impact on quality. MP3 files are widely supported across devices.1
WAV – An uncompressed audio format that provides high quality sound. However, WAV files are large in size compared to lossy formats like MP3. WAV is supported by Windows and macOS.2
FLAC – Stands for Free Lossless Audio Codec. FLAC also provides CD-quality audio in an open and royalty-free format. File sizes are much smaller than WAV but larger than MP3. FLAC is supported by many devices and software.3
AAC – Advanced Audio Coding format that is commonly used on mobile devices and streaming services. Provides good quality at smaller file sizes like MP3. AAC is the default format for Apple devices.
There are several factors to consider when choosing an audio format, such as sound quality needs, file size limitations, and device or software compatibility.
Storing Audio on SD Cards
SD cards are well-suited for storing audio files. The most common audio file formats – MP3, WAV, FLAC, AAC, etc. – can be directly copied to an SD card’s file system. Both Windows and Mac computers recognize SD cards as external removable storage devices, allowing you to easily drag and drop audio files like you would with a USB flash drive or external hard drive. SD cards support standard file systems like FAT32 and exFAT that fully support these audio formats.
One of the biggest advantages of using SD cards for audio storage is their large capacities, which allow you to store many songs or long hours of recordings. For example, a common 32GB SD card can hold over 200 albums in MP3 format, while a 1TB SD card could store over 15,000 albums [1]. High capacity cards make SD cards a versatile solution for portable audio storage.
SD Card Speeds for Audio
The speed of an SD card can affect its ability to effectively record and store audio files without issues. SD cards have speed classes ranging from Class 2 (minimum write speed of 2 MB/s) up to Class 10 (minimum 10 MB/s) and UHS classes with even faster speeds.
For basic audio recording, even a slower Class 4 card may be sufficient. According to Acoustic Nature, recording 4 channels or less at 96kHz/32-bit can be done on the slowest Class 2 SD card. However, higher resolution formats like 192kHz/32-bit may require a faster Class 10 card to avoid recording issues.
As noted on the Sweetwater Sound musician’s guide, SD card speed mainly affects the time it takes to transfer audio files on and off the card. Using a faster UHS-I or UHS-II card can significantly speed up workflow when transferring large batches of high resolution audio. But the actual audio quality is not affected by transfer speed.
On Reddit’s LocationSound community, the recommendation is to use the specific SD cards recommended for your particular audio recorder. The card specs will be optimized for the write speeds required by that device for flawless audio recording.
So in summary, while Class 10 and UHS cards are not always mandatory, they provide enough speed headroom to ensure reliable recording with any audio format. And they will greatly accelerate file transfers to and from a computer for post-production.
SD Card Capacities for Audio
The storage capacity of SD cards determines how much audio content they can hold. SD cards come in a wide range of capacities, from 4GB to 1TB and beyond. The most common capacities used for audio storage include:
16GB – Stores around 4,000 songs or 28 hours of high quality audio 1
32GB – Stores around 8,000 songs or 56 hours of high quality audio
64GB – Stores around 16,000 songs or 112 hours of high quality audio
128GB – Stores around 32,000 songs or 224 hours of high quality audio 2
256GB – Stores around 64,000 songs or 448 hours of high quality audio
As you can see, higher capacity SD cards allow you to store more audio files and songs. For portable everyday listening, 16-64GB cards are recommended. For larger libraries, audiophiles may want 128-256GB cards. Choose a capacity that fits your audio storage needs.
Audio Quality Considerations
When storing audio on SD cards, the most important factors that determine audio quality are bitrate and sample rate. The bitrate is the amount of data used per second to store the audio information. Higher bitrates allow for better audio quality, but result in larger file sizes. Common bitrates for audio files include 128kbps, 192kbps, 256kbps, and 320kbps. The sample rate is how many times per second the audio waveform is sampled. Common sample rates are 44.1kHz and 48kHz.
The most common audio file formats used for storing music on SD cards are MP3, AAC, FLAC, WAV, and AIFF. MP3 and AAC use lossy compression, which reduces file size at the cost of some loss of audio quality. FLAC, WAV, and AIFF are lossless formats that preserve full audio quality but result in much larger file sizes. FLAC offers the best balance of quality and file size. The format you choose depends on your storage space available versus desired audio fidelity.
To get the highest quality audio from an SD card, choose lossless formats like WAV or FLAC, use the highest bitrate your storage allows, and use a sample rate of at least 44.1kHz. However, acceptable audio can still be achieved with reasonable MP3 bitrates if storage space is limited. The SD card speed is less important for audio than video (see source).
Other Advantages of SD Cards for Audio
In addition to their ability to store high-quality audio files, SD cards provide several other key advantages for audio storage and playback:
Portability: SD cards are highly portable and compact, allowing you to easily transport large audio libraries wherever you go. The small physical size of SD cards makes them convenient to carry around.
Affordability: SD cards provide an affordable storage solution compared to many other media formats. High capacity SD cards capable of holding hours of audio can be purchased for low prices. This makes them a very cost-effective option. According to Acoustic Nature (https://acousticnature.com/journal/best-sd-card-for-recording-audio), SD cards are typically more affordable than other portable audio storage devices.
Compatibility: SD cards use a universal format that allows compatibility with a wide range of devices including DSLR cameras, smartphones, tablets, handheld recorders and more. This cross-device functionality makes them extremely versatile for audio playback.
Durability: SD cards are designed to withstand rugged use and extreme environmental conditions. Their solid-state flash memory construction makes them far more shock and vibration resistant than hard drive-based audio devices (https://www.sweetwater.com/sweetcare/articles/musicians-guide-to-using-sd-cards/). SD cards can better endure on-the-go audio recording and playback.
Other Options for Portable Audio Storage
In addition to SD cards, there are other options for storing and transporting audio files:
USB Flash Drives
USB flash drives, also known as thumb drives, are a popular portable storage device. They connect via USB ports and do not require a card reader. High capacity USB drives can store many hours of audio, and transfer speeds are generally fast. However, they are not as durable as SD cards and can be easily damaged or lost.
External Hard Drives
External hard disk drives (HDDs) offer very large capacities for audio storage. A portable external HDD can store entire music libraries with room to spare. Transfer speeds can be excellent over USB 3.0 or Thunderbolt. However, HDDs are larger, require an external power source, and are more prone to damage from drops or impacts compared to flash memory.
Cloud Storage
Cloud storage services provide abundant capacity for audio files. Audio can be uploaded and streamed from anywhere with an internet connection. However, continuous internet access is required, and slower connections can impact streaming quality. There are also recurring subscription costs associated with most cloud services.
SD Cards Are Great for Audio Storage
SD cards are an excellent option for storing and transporting audio files. Here’s a quick summary of some of the key advantages:
- High capacities – SD cards are available in capacities up to 1TB, allowing you to store thousands of songs in a tiny form factor.
- Portability – SD cards are extremely compact and lightweight, making them easy to take anywhere.
- Affordability – Higher capacity SD cards have become much more affordable in recent years.
- Durability – SD cards have no moving parts and are resistant to shock, vibration, water, magnetism, and extreme temperatures.
- Compatibility – SD cards can be used with a wide range of devices including DAPs, phones, tablets, computers, cameras, and more.
- Speed – Modern SD cards offer fast data transfer speeds for smooth playback.
- Removable – SD cards are simple to insert and remove from devices.
- Reliable – SD cards from reputable brands offer reliable performance for audio storage.
With their impressive capacities, affordability, durability, and wide compatibility, SD cards make it easy and convenient to store and access your music library on the go. Their compact size also makes them a smart choice for expanding limited internal storage on mobile devices. For portable audio playback, SD cards tick all the right boxes.