Hello friend! With ultra-high definition (UHD) and 4K video streaming becoming mainstream, video compression tech plays a vital role in delivering highest quality video while minimizing network bandwidth requirements. This is where advanced video codecs like AVC and HEVC make their mark.
In this guide, we will decode these complex video codec standards to understand their inner workings and how they enable smooth video streaming to your devices. We will see how HEVC builds on AVC foundations to offer 50% improved compression efficiency. We will also discuss why HEVC is the default choice for 4K streaming while AVC continues to power a bulk of today‘s HD video distribution.
So whether you are a budding media professional or just a video quality enthusiast, read on as we uncover secrets behind these magical video compression algorithms!
Why Care About Video Codecs Anyway?
Before we dive deeper, let me quickly explain what video codecs do and why they matter.
Video codecs apply complex mathematical algorithms to encode raw digital video frames into compact binary files that can be easily stored or streamed over networks. Some key techniques used include:
- Predicting content across video frames
- Transforming pixel blocks to concentrate energy
- Quantization to achieve lossy compression
- Entropy encoding to represent transform data efficiently
The above steps comprise the fundamentals of any video encoding pipeline as the diagram shows below:
By applying these techniques selectively, video codecs strike the right balance between:
- Preserving perceptual video quality
- Reducing video bitrate drastically
This allows us to stream or store beautiful 4K video content at just 15-20 Mbps instead of over 1 Gbps required for the raw uncompressed video!
Modern video codecs like AVC and HEVC squeeze out every bit of redundancy in video data through improved predictions and transforms – saving precious bandwidth for consumers and cost for service providers!
Now let us take a quick look at AVC first before moving to its successor HEVC.
AVC (H.264): The Gold Standard for HD Video
AVC which stands for Advanced Video Coding formed the backbone of HD video distribution over the past decade across Blu-rays, YouTube, cable TV and our handy mobile devices!
Also known as H.264 or MPEG-4 Part 10, this video codec was first defined by the JVT (Joint Video Team) standards body way back in 2003. The intent was to create a successor to the MPEG-2 codec used for DVDs at that time. And AVC delivered on that goal in spades enabling smooth 1080p 30fps HD video streaming on 6-10 Mbps broadband connections.
I will skip the alphabet soup of technical jargon and explain how AVC works using easy to grasp concepts.
AVC Encoding Process Made Simple
The image below outlines the various steps involved in H.264 encoding pipeline:
Here is what is happening inside AVC:
- The video frame is first divided into Macroblocks – small 16×16 pixel regions
- For each region, encoder tries to find matching blocks in previously encoded video frames
- This predictive coding step removes redundancies exploiting the fact that video content doesn‘t change much across consecutive frames
- The prediction residual (difference from the actual block) undergoes Lossy transform coding
- Friendly math transforms concentrate residual energy allowing drastic quantization (the lossy part!)
- Finally entropy coding step stores transform data very efficiently as a compact bitstream
This pipeline repeats for every frame in the video sequence ultimately producing the compressed AVC bitstream.
Feeling comfortable with the core concepts? Now lets dive deeper under the hood to truly appreciate the engineering marvel called H.264!
Inside AVC: Key Innovations Behind its Efficiency
AVC introduced a number of clever innovations which enabled HD video transmission at just 5-10 Mbps bitrates compared to over 100 Mbps required by prior MPEG-2 codec!
Some of the key improvements included:
Smaller Block Sizes
Unlike MPEG-2 which worked on 16×16 pixel blocks, AVC allows block divisions down to 4×4 pixels. This flexibility improves prediction accuracy in regions with high details.
Quarter Pixel Precision Motion Compensation
Matching static backgrounds across frames enables high compression ratios through motion compensation. AVC enables 1/4th pixel precision in motion vectors taking this to the next level!
Multiple Slice Group Support
AVC allows frames to be divided into multiple slices that can be encoded and decoded independently. This brought support for parallel processing which is vital for UHD and 4K requirements.
In-loop Deblocking Filters
One downside of lossy compression is annoying blocking artifacts at high compression ratios. To mitigate this, AVC applied clever deblocking filters within the encoding loop to smoothen final visual quality.
And boy, did these innovations work or what! AVC hit a sweet spot providing the right video quality and bit efficiency trade-offs enabling HD video streaming reach billions of screens around the world! 📺
But by 2010, 4K resolution smart TVs and tablets started popping up in electronics showrooms! This required a new breed of ultra-efficient video codecs, bringing us to…HDR-capable High Efficiency Video Coding!
HEVC (H.265) – Supercharged for the 4K Streaming Era!
When current generation 4K UHD and high dynamic range (HDR) displays hit the market, it was clear AVC will struggle to stream such content efficiently.
A successor was needed that can:
- Handle high resolution beyond HD efficiently
- Enable HDR video grade to maximize quality
- And of course, do all this at half the bitrates!
HEVC, short for High Efficiency Video Coding, answered the call providing radical improvements over H.264 to power today‘s streaming era! 🦸♂️
Also called H.265, HEVC‘s core techniques and building blocks match previous standards, but with far more advanced tools under the hood! HEVC hit the market first in 2013 promising double the compression efficiency gains over AVC.
I will decode the magical ingredients that make HEVC shine for delivering stunning 4K video to your devices!
Flexible Coding Block Sizes
One key improvement in HEVC was support for adaptive coding tree block sizes ranging from 4×4 to 64×64 pixels compared to fixed 16×16 blocks in AVC.
This huge flexibility in block shapes and sizes allowed HEVC encoder to selectively apply transformations only in regions with finer details vs flat backgrounds.
The impact? Over 25% bitrate savings while maintaining perceivable quality!
Parallel Processing Support
HEVC brought parallel processing into mainstream by supporting frame and in-frame tile partitioning. Multiple slices could now be independently encoded/decoded in parallel leveraging multi-core processors.
This was a boon for software implementation on CPUs and critical to achieve real-time performance for 4K video.
Improved Motion Compensation
HEVC uses advanced motion vector prediction (AMVP) where previously decoded motion vectors predict values for current blocks improving coding efficiency.
Motion compensation could now apply across 64×64 pixel groups enabling matching static background regions more effectively.
Better In-Loop Filters
Like AVC, HEVC applies multiple deblocking filters within coding loop to reduce blocking artifacts. But HEVC filters operate across larger 64×64 block boundaries vs 16×16 blocks in AVC.
This along with adaptive sample offset filter achieves visibly smoother image quality.
Above examples highlight the many incremental innovations packed into HEVC that enabled UHD 4K video delivery with existing networks and hardware!
And now supported by all major hardware devices and streaming services, HEVC continues to power global video growth through 2025! 📈
Now that you understand both codecs at a technical level, let us move on to tangibly compare their performance and adoption trends shaping real-world streaming services.
HEVC vs AVC: Quantitative Performance Benchmarks
While we qualitatively covered HEVC improvements over AVC earlier, actual performance comparisons across real video data will help us quantify exact gains.
We will analyze AVC vs HEVC across parameters like encoded video bitrate, quality achieved, encoding times and more using published research benchmarks.
Test 1: Video Quality & Bit Rate Savings
Let‘s first see HEVC gains in action across Netflix‘s public test video streams, a great proxy for real-world viewing!
- At mid tier SD quality targeting 500 kbps, HEVC shows 36% lower bitrates over AVC for matching quality levels
- The gap widens moving to HD & UHD streams with HEVC streams needing 50% lower bandwidth!
Above graph highlights the bitrate advantages powering Netflix HEVC 4K delivery cost-effectively even at 15 Mbps streams!
Test 2: Video Resolution Scaling
Bitrate savings directly translate to higher resolutions possible at fixed bandwidths as below Intel test reveals:
We see HEVC can support 4K resolution atbitrate where AVC maxes out at 1080p! This shows advantage for OTT providers to scale quality for customers as internet speeds improve!
Test 3: Hardware Encoding Efficiency
On commercial encoding hardware, HEVC proved 15-40% faster than AVC at UHD resolutions as tabulated below:
| Codec | Encode Time (Lower is better) |
|---|---|
| AVC | 22 s |
| HEVC | 14 s |
Smart encoder optimizations like tile-based parallel processing help HEVC reduce encoding times even with increased computational complexity!
Above real-world tests give you a quantifiable glimpse into the upgrade HEVC offers for streaming high quality video on fixed broadband connections!
Now let us shift gears to adoption trends as more OTT streaming providers double down on HEVC for their UHD distribution.
HEVC Adoption Rising Fast; AVC Still Relevant Though
Given its clear technical advantages, you might wonder if HEVC will completely replace AVC anytime soon. The answer is a little complicated so let me break down adoption trends across various video applications:
Blu-Ray Disc Adoption
UHD Blu-Ray format released in 2015 mandates HEVC encoding for all titles. Being a high margin format, codec licensing costs are not a barrier here helping drive 100% HEVC usage for UHD Blu-Ray movie releases.
Broadcast TV
Early HEVC support started with experimental UHD channels by stations like NHK Japan, Sky UK. But broader adoption is expected only by 2023-24 timelines across US and Europe. AVC will continue to power majority of HD cable channels in the interim.
Video Streaming Services
OTT services like Netflix, Amazon Prime pioneered HEVC 4K delivery in 2015. Recently Disney+, Discovery+ too joined the bandwagon. Collectively, HEVC now powers 60% of global video traffic thanks to streaming explosion!
HEVC brings major bandwidth savings especially for mobile viewers. So its growth trajectory seems solid despite debut of newer codec rivals like VVC, AV1 that promise better compression.
Video Conferencing
AVC continues its reign here with widespread software and hardware acceleration support. HEVC adoption is limited to high-end enterprise video conferencing solutions currently.
User Generated Content
YouTube still defaults to AVC given its hardware decoding support across billions of old and low-end devices out there. Though creators can optionally upload HEVC content, transcoding penalties may apply.
Above use cases give you a perspective into church HEVC adoption across media industries based on unique needs. There is always an inertia with old standards, but HEVC momentum is real and unstoppable beyond 2025!
Now as discerning video quality experts and consumers, let us wrap up with guidelines to pick AVC vs HEVC for your specific needs:
AVC or HEVC? Recommendations and Factors to Consider
Based on comparative analysis so far, here are some guidelines I can provide:
Use AVC When
- Targetting legacy or low-end viewing devices
- Focus is highest quality HD, not UHD video
- Using video conferencing/collaboration software
- Cost is a major factor over bandwidth savings
Pick HEVC For
- Highest resolution UHD, 4K or 8K video
- Adding HDR for enhanced color and contrast
- Reducing operating costs via lower bitrates
- Future-proofing video libraries for next-gen displays
Within the options above, I would suggest analyzing critical factors below that apply to your specific use case:
- Target Display Resolution & Quality
- If UHD+ resolutions needed now or later, HEVC only choice
- Network Conditions
- For mobile or poor broadband, HEVC‘s bitrate savings are vital
- Hardware Decoding Support
- If targetting low-end devices, ensure HEVC hardware support
- Encoder Complexity & Costs
- HEVC encoding may require upgraded software tools or cloud services
I hope above guidelines help narrow down codec selection to best suit your needs – whether you are a media enterprise, video developer or just a savvy consumer wanting to enjoy best visual experiences! 😊
And I believe this brings us to the end of our insightful walk-through of AVC and HEVC video compression standards powering the vibrant video streaming ecosystems around us today!
We went from understanding the fundamental concepts to a detailed technical dive into latest innovations that make HEVC outshine AVC for delivering immersive 4K viewing experiences! And learned about the trends shaping adoption and relevance of these codecs over the next decade!
I hope you had as much fun reading this guide as I had writing it! Feel free to ping me any other questions you may have around codec selection for your specific application.
Happy video streaming to your hearts content! 🖖
