Because HDMI cables can deliver audio as well as video, they’re also used for connecting media sources to AV receivers and the like, making it a viable competition against S/PDIF or SPDIF and optical/TOSLINK cables as well. HDMI cables are all-around devices that can outdo its SPDIF counterpart in certain respects, but you shouldn’t underestimate the value of a SPDIF connection either. You can’t always default to using HDMI for everything, especially when SPDIF is instead available.
When it comes to SPDIF vs HDMI, it’s mostly a debate regarding sound connections instead of one concerning video connections. In particular, HDMI is fast becoming the de facto connection for soundbars, speakers, and AV receivers versus SPDIF or even TOSLINK the same way it took HDTV by storm.
What Is SPDIF?
SPDIF or S/PDIF refers to the Sony/Philips Digital Interface. It’s a type of digital audio connection standard used in consumer audio appliances and equipment for short-distance audio output. Ostensibly, it was developed through the combined forces of Philips and Sony. The signal is supposed to travel over a fiber optic cable with TOSLINK connectors or a coaxial cable with RCA connectors. SPDIF interconnects components in digital hi-fi systems such as home theaters with AV receivers.
Furthermore, the standard is based on AES3 Interconnect. It also carries 2 channels of compressed 5.1 or 7.1 surround sound like the one found in the DTS audio codec or uncompressed PCM audio for the highest quality and clearest sound possible without any distortion, audible pop, or scratchy static whatsoever that is reminiscent of the sound you hear when you’re frying something in oil. It does have limits though, like its inability to support lossless surround formats. Those formats require a larger amount of bandwidth than what S/PDIF can provide.
What Is HDMI?
High-Definition Multimedia Interface or HDMI is a propriety A/V interface and connection standard. It’s the de facto standard for the transmission of uncompressed video data and uncompressed/compressed digital audio feeds from a source media device that’s HDMI-compliant. These devices could be any range of appliances, such as a digital audio device, AV receiver, digital television, HDTV, video projector, compatible computer monitors in lieu of VGA connections, and so forth.
Because it’s the current standard for HD streams and content that has outdone its peers DVI (Digital Visual Interface) and DP (DisplayPort), expect there to be a whole load of HDMI converters that allow you to play source media of an older vintage on an HDTV. For the purposes of this article, we’ll be covering the audio aspect of HDMI connections and HDMI cables, since they’re capable of transporting uncompressed or compressed LPCM audio along with video formats, waveforms, auxiliary data, and VESA EDID implementations in accordance to EIA/CEA-861 standards.
HDMI versus SPDIF: How Do They Compare?
Let’s now discuss the nitty-gritty of this article, which is how HDMI connections for audio use compare to the S/PDIF audio linkage standard. When hooking up your audio system for your computer, HDTV, cable/satellite box, DVD/Blu-ray Disc player, and so forth, you usually use an optical digital-audio connection or an HDMI cable since that can carry sound just fine on its own.
SPDIF optical digital audio and HDMI connections are your two main choices when connecting your AV receiver or soundbar to your source media. Which standard is better? Which is worse? Which is better in certain applications and worse in others? Keep on reading.
- What Is an AV Receiver Anyway? You will most likely use your HDMI for audio or SPDIF optical cable on what’s known as an audio/video receiver, also known as an A/V or AV receiver. This device is a consumer electronics component mainly used in home theaters to connect sound systems to different source media and video displays with ease. It’s capable of receiving both video and audio signals from a number of devices in order to process them all with the efficiency of a matrix switch or splitter. It also drives loudspeakers and provides power amplifiers on top of routing the video signals to displays like TVs, computer monitors, and projectors.
- The Simplest Advice: Just as people used to default to RCA connections for their A/V needs or optical cables for their audio needs, so too should they default to HDMI whenever possible. HDMI is the current generation standard for HD video and hi-fi audio bar none, with DVI and DP trailing behind in comparison to how ubiquitous it is. It’s the peak technology for compressed and uncompressed audio data as well as HD video feeds out there, with every new specification improving its capabilities over time. However, if you lack HDMI, SPDIF isn’t the worst thing in the world to get an AV receiver connection from either.
- The Basic Comparisons: Both HDMI and S/PDIF with optical cables pass digital audio from one device to the next or from source media to sound display like stereo speakers or a soundbar as well as an AV receiver. They’re both better than the red and white cables of analog stereo audio when it comes to delivering high-fidelity sound. They’re mutually capable of passing multi-channel audio such as the one found in Dolby Digital. Both optical cables for SPDIF and HDMI cables for HDMI ports are relatively cheap as well.
- The Biggest Difference: HDMI is better because it’s capable of passing higher-resolution audio that’s uncompressed, which includes extra formats that won’t translate as well through optical cable and S/PDIF like Blu-Ray’s DTS HD Master Audio and Dolby TrueHD. Optical can’t transmit those formats. It’s not quite the difference between mono and stereo sound, but there’s a lot missing when you switch from full HDMI to SPDIF for your sound requirements when watching the latest Blu-Ray or streaming HD video from your cable box.
- What SPDIF Brings to the Table: The data link layer protocol known as Sony/Philips Digital Interface is a set of physical layer specifications made to carry digital audio signals between two devices or intermediary components like the AV receiver over an electrical or optical cable. Its SPDIF name actually stands for Sony/Philips Digital Interconnect Format but it got another moniker that fits the acronym of Sony/Philips Digital Interface. The primary designers of the standard were (obviously) Sony and Philips, with its support to standardize IEC 60958 and IEC 60958 Type II (the ICE 958 before 1998).
- The Limitations of SPDIF: Because of bandwidth and when it was developed, SPDIF is a limited audio format altogether. It can handle DTS 5.1, Dolby Digital 5.1, and Stereo. That’s about it. It doesn’t support multi-channel audio support that’s lossless or uncompressed. There was once an era where DTS or Dolby were the go-to audio providers in town and it was convenient to hook up your AV equipment via the SPDIF format. However, it’s become obsolete in light of the strides in lossless audio and HDMI technology.
- Convenience, Thy Name Is HDMI: HDMI is superior in every way to SPDIF. It passes video signals along with audio signals in one cable. This makes the standard and its cable streamlined and convenient. You only have to deal with one wire between two devices versus multiple separate ones. Additionally, with HDMI, no signal conversion is required. You won’t get video quality loss when doing a DVI-to-HDMI adapter connection as well. HDMI also has the Consumer Electronics Control (CEC) feature that allows HDMI devices to control one another when needed.
- When HDMI Isn’t Ideal: You might have to go the S/PDIF route if HDMI isn’t an option for your gear. It could be vintage gear or it could be something that only has SPDIF ports, so optical cables can only be used instead of HDMI in lieu of adapters and converters. Sure, SPDIF is much more primitive than its HDMI counterpart with its lack of CEC that allows you to operate multiple HDMI-compatible devices with one handheld remote control, but in terms of quality hi-fi sound, it’s more than enough for your needs. While you can technically convert a SPDIF port to allow it to work with an HDMI cable for a modern soundbar, it’s best to go optical with SPDIF to vintage AV receiver or speaker connections.
HDMI doesn’t only compete against video standards from the past to the present. It’s not only comparable to its competition, DisplayPort or DP (successor), and DVI (a predecessor). It’s not only the current HDTV A/V standard comparable to VGA (computers) and component video/S-video/composite standard (analog TV). It’s also comparable to the world of audio connections, stereos, AV receivers, and home theaters. HDMI offers the best of both worlds in terms of high-definition video and high-fidelity audio with every new specification released for it.
Both S/PDIF and HDMI have their respective pros and cons, so in regards to which is better, it’s ultimately a question of application and/or circumstance. Which connection type is more practical, affordable, or available? That’s how you determine which connection standard to go for when push comes to shove. For example, while HDMI is objectively better quality-wise, when dealing with vintage electronics it’s more practical to use optical cables over a SPDIF connection versus using adapters to shoehorn HDMI cables into the mix.
- Geoffrey Morrison, “HDMI vs. optical: Which digital-audio connection to use?“, Cnet.com, March 13, 2014
- “SPDIF (Opitcal Audio) vs. HDMI“, Tom’s Guide, May 3, 2017