In a nutshell
- The new game in town is H.265, and it’ll do everything H.264 did, only smaller, quicker and better.
- H.264 is a highly efficient video codec, but advancements like 4K video mean better streaming efficiency is necessary.
- If we haven’t started using H.265, it’s important to take a look at what it is, why it’s better and when to use it.
The way we deliver video has been improving as well. Streaming has grown exponentially over the last decade, and technology is capable of bringing “The Mandalorian” (2019 – present) into homes around the world, in crystal clear 4K. But it can’t just be about the infrastructure that delivers videos that improves to make great streaming possible. The actual video encoding we, as creators, employ can have a massive impact on streaming performance. In recent years, H.264 (AVC) has been an excellent standard, allowing for high-quality, small file-sized videos that are wholly appropriate for streaming high-definition videos. But we’re not just streaming HD anymore. Many households have upgraded to 4K televisions, and most streaming services can accommodate 4K video. While H.264 has been an excellent standard, the bandwidth requirements for streaming 4K H.264 video are just too high to ensure smooth, uninterrupted playback. Fortunately, a new standard for better-than-HD streaming has come along in the form of H.265, or HEVC.
As this shift from the old standard to the new standard occurs, comparisons are inevitable, but before looking at why this new standard is better, let’s take a look at what H.264 and H.265 are and how they work.
H. 265’s origin story
To begin, H.264 and H.265 are both video codecs. Simplified, a video codec is the software used to compress video into a digital format or file, which allows playback devices to decompress them so they can be viewed as they were originally shot. There’s a bit more to it than that, but that’s the gist.
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Most video content is encoded with an audio stream as well and bundled into a container file. A couple of examples of container files are AVI or MP4. Other popular codecs/containers include Apple’s ProRes family of codecs and their Quicktime MOV container format.
While H.264 and H.265 are video encoding formats, those audio streams would be created using an audio encoding format such as MP3 or AAC. Interestingly, while most encoded audio also goes into a container file when delivered – for instance, your raw AAC audio might be exported in a .m4a file – some formats, such as MP3, are a raw audio format that doesn’t require a container.
But let’s get back to video.
Acronyms
As we mentioned earlier, comparing the long-running H.264 standard and H.265 is inevitable. So, let’s start with their acronyms.
- H.264 is also known as AVC, or Advanced Video Codec
- H.265 is also known as HEVC, or High Efficiency Video Codec
Why is H.265 the new standard?
While both H.264 and H.265 are efficient, the biggest difference between them is that they process the data they contain differently. H.265 is capable of jamming large information into smaller file sizes, using less bandwidth when streaming.
How do these codecs work?
Both AVC and HEVC codecs use a compression technique that implements motion compensation to keep file size down and performance and image quality high. To get technical, they both use motion-compensated discrete cosine transform (DCT) hybrid coding.
Put simply, motion compensation compression in digital video uses an algorithm that takes advantage of the fact that very often frames in a video only change based on the movement of the camera, or perhaps an object within the frame.
Based on this, the algorithm compares future and past frames of video to estimate much of the information stored in the next frame. It also means frames that don’t change don’t need additional information stored for them.
Our codecs differ in how they process the information they compress. Let’s take a look.
AVC/H.264
H.264 uses a block-oriented motion compensation standard. Frames are divided into units called macroblocks, which can be divided and subdivided to make frame prediction efficient.
The H.264 compression algorithm is what really helped it become the go-to codec over earlier standards. Smaller file sizes and lower bitrates meant smoother, higher-quality streaming and were ultimately integral in driving the success of sites such as YouTube.
HEVC/H.265
In contrast with H. 264’s block-oriented motion compensation standard, H.265 uses coding tree units or CTUs. While the macroblocks in H.264 worked in either 4 x 4 or 16 x 16 block sizes, H. 265’s CTUs can process 64 x 64 blocks, leading to more efficient compression.
All of that new and efficient compression the CTUs bring about does come at a bit of a price on the streaming side. Better, more powerful hardware and software is required to stream H.265. However, on the bright side, it means that those viewing the content will require less processing power and bandwidth to view a stream.
Ultimately, this means better compression means smaller files and the ability to stream higher quality videos at a lower bandwidth cost.
How much less bandwidth are we talking?
When talking about codec efficiency, and particularly for streaming 4K video, file size is not the most important factor. Bitrate is. And H.265 requires approximately 50 percent of the bandwidth that H.264 requires. It also cut down the storage requirement by around that same percentage.
Let’s put that into perspective. According to the folks at Boxcast, broadcasting 4K in AVC requires a bandwidth of 32 Mbps. Broadcasting the same 4K in HEVC requires 15 Mbps.
This is important as, according to the Akamai State of the Internet Report, the average internet speed in the US is 18 Mbps.
What about H.265 variants?
We’ve looked pretty closely at H.264 vs. H.265, but what about the other terms associated with H.265 out there? Let’s have a look at a couple.
- H.265+: This codec improves on the motion compensation and frame referencing used in H.265, further decreasing bitrates. In most scenarios with relatively still background content, H.265+ sees a 30 percent bitrate savings over H.265. Expect to hear more about this codec in the future.
- x265: Where H.265 is the standard, x265 is software that encodes to that standard. The Joint Collaborative Team developed it on Video Coding (JCT-VC).
Wrapping it all up
Whether you shoot event video, corporate spots, commercials or social content, producing the most efficient content possible always makes sense. Most things we create end up streamed, posted, shared or otherwise sent traversing the World Wide Web. If a future project doesn’t have delivery specs pre-defined, give H.265 a closer look. The bitrate advantage alone might be enough to convince, but the general advancements and efficiencies over past standards make it a codec worth our attention. Whether making the leap now or in six months, it pays us to research and know the latest tech, when to use it and why it’s the best choice.