With video consumption rising and consumer preferences shifting to 4K UHD this is contributing to an even faster adoption rate than what we saw with the move to HD TV. Consumer demand for a seamless (buffer-free) video experience is a new expectation, and with the latest announcement from HEVC Advance removing royalty uncertainties in the market it’s time to start thinking about building and deploying an HEVC workflow, starting with a robust HEVC encoder.
As you may know, Beamr’s V.265 was the first commercially deployed HEVC codec SDK and it is in use today by the world’s largest OTT streaming service. Even still, we receive questions regarding V.265 in comparison to x265 and in this post we’d like to address a few of them.
In future posts, we will discuss the differences in two distinct categories, performance (speed) and quality, but in this post we’ll focus on feature-related differences between V.265 and x265.
Beginning with our instruction set, specifically support for X86/x64 SMP Architecture, V.265 is able to improve encoding performance by leveraging a resource efficient architecture that is used by most multiprocessors today. Enabling this type of support allows each processor to execute different programs while working on discrete data sets to afford the capability of sharing common resources (memory, I/O device interrupt system and so on) that are connected using a system bus or a crossbar. The result is a notable increase in overall encoding speed with V.265 over x265. For any application where speed is important, V.265 will generally pull ahead as the winner.
Another area V.265 shines compared to x265 is with its advanced preprocessing algorithm support that provides resizing and de-interlacing. As many of you know, working with interlaced video can lead to poor video quality so to try and minimize the various visual defects V.265 uses a variety of techniques like line doubling where our smart algorithms are able to detect and fill in an empty row by averaging the line above and the line below. The advantages of having a resizing feature is recognizable, largely saving time and resources, and out of the box V.265 allows you to easily convert video from one resolution to another (i.e. 4K to HD). One note, we are aware that x265 supports these features via FFMPEG. However in the case that a user is not able to use FFMPEG, the fact that V.265 supports them directly is a benefit.
V.265 boasts an unmatched pre-analysis library with fading detection and complexity analysis capabilities not supported in x265. An application for the V.265 library is video segmentation that is problematic with many encoders because of the different ways two consecutive shots may be linked. In V.265, the fading detection method detects the type of gradual transition, fade type etc. which is needed to detect hard to recognize soft cuts. V.265’s complexity analysis is able to discriminate temporal and spatial complexity in video sequences with patented multi-step motion estimation methods that are more advanced than standard “textbook” motion estimation algorithms. The information gained from doing a video complexity analysis is used during the encoding process to improve encoding quality especially during transitions between scenes.
One of the most significant features V.265 offers compared to x265 is multistreaming (ABR) support. V.265 can produce multiple GOP-aligned video output streams that are extremely important when encoding for adaptive streaming. It is critical that all bitrates have IDRs aligned to enable seamless stream switching, which V.265 provides.
Additionally, with V.265 users can produce multiple GOP-aligned HEVC streams from a single input. This is extremely important for use cases when a user has one chance to synchronize video of different resolutions and bitrates. Multistreaming helps to provide encoded data to HLS or DASH packagers in an optimal way and it provides performance savings – especially when the service must output multiple streams of the same resolution, but at varying bitrates.
Another significant feature V.265 has over x265 is its content adaptive speed settings that makes codec configuration more convenient such as real-time compared to VOD workflows. Currently we offer presets ranging from ultra fast for extremely low latency live broadcast streams to the highest quality VOD.
To combat packet losses and produce the most robust stream possible, V.265 supports slicing by slice compressed size which produces encoded slices of limited sized (typically the size of a network packet) for use in an error prone network. This is an important feature for anyone distributing content on networks with highly variable QoS.
Continuing on to parallel processing features, V.265 offers support for tiles that divides the frame into a grid of rectangular regions that can be independently decoded and encoded. Enabling this feature increases encoding performance.
V.265 is regarded as one of the most robust codecs in the market because of its ability to suit both demanding real-time and offline file based workflows. To deliver the industry leading quality that makes V.265 so powerful, it offers motion estimation features like patented high performance search algorithms and motion vectors over a picture boundary to provide additional quality improvements over x265.
For encoding by frame-type, V.265 offers Bi- and uni-directional non-reference P-frames over x265. This is useful where low-delay encoding is needed to improve temporal scalability. Additionally, V.265 supports up to 6 reference frames compared to 3 with x265, which helps improve encoding efficiency.
As for encoding tools, V.265 offers a unique set of tools over x265:
- Joint bi-directional Motion Vector Search which is an internal motion estimation encoding technique that provides a better bi-direction motion vector search.
- Sub-LCU QP modulation that allows the user to change QP from block to block inside LCU as a way to control in-frame bits/quality more precisely.
- Support for up to 4 temporal layers of multiple resolutions in the same bitstream to help with changing network conditions.
- Region of Interest (ROI) control which allows for encoding of a specific ROI with a particular encoding parameter (qp) to add flexibility and improve encoding quality.
Another major advantage over x265 is the proprietary rate control implementation offered with V.265. This ensures target bitrates are always maintained.
The more supplemental enhancement information (SEI) messages a codec supports the more video usability information (VUI) metadata that may be delivered to the decoder in an encoded bitstream. For this reason, Beamr found it necessary to include in V.265 support for Recovery point, Field indication, Decoded Picture Hash, User data unregistered, and User data as specified by ITU-T T.35.
V.265’s ability to change encoding parameters on the fly is another extremely important feature that sets it apart from x265. With the ability to change encoder resolution, bitrate, and other key elements of the encoding profile, video distributors can achieve a significant advantage by creating recipes appropriate to each piece of content without needing to interrupt their workflows or processing cycles to reset and restart an encoder.
We trust this feature comparison was useful. In the event that you require more information or would like to evaluate the V.265, feel free to reach out to us at http://beamr.com/info-request and someone will get in touch to discuss your application and interest.