Vcodex is recruiting

We're looking for an experienced software developer / consultant to work on video coding software and analysis. If you're interested in challenging work at the forefront of video compression, please get in touch. For more information, please contact Ruth Easton: http://www.linkedin.com/in/rutheaston quoting reference VCODEX01.

HEVC: is it really twice as good as H.264?

The new standard for video compression, High Efficiency Video Coding or HEVC, is claimed to require "half the bandwidth for high quality video transmission", compared with the older H.264/AVC standard. What does this mean? If the same video clip is encoded with H.264 at a particular bitrate, and with HEVC at half the bitrate, then the quality of the decoded HEVC video should be at least as good as the decoded H.264 video.

Here's an example. This is a close-up of a frame from the sequence "Kristen and Sara", 720p resolution. On the left, the sequence has been encoded at 800kbps using the x264 video encoder, a popular H.264 implementation. On the right is the same frame from the sequence encoded at 420kbps using the HEVC Test Model encoder, HM10.0. The frame on the right was decoded from one of the HEVC Anchor Sequences (Kristen and Sara, QP=32) which you can download here: ftp://ftp.kw.bbc.co.uk/hevc/hm-10.0-anchors/bitstreams/ra_main/. The original YUV test sequences are available here: ftp://hvc:US88Hula@ftp.tnt.uni-hannover.de/testsequences.

Left: x264 at 800kbps. Right: HM10 at 420kbps.

The two frames look very similar. However, some detail is lost in the HEVC version. You can see this more clearly here:

x264 at 800kbps: extreme close-up

HM10 at 420kbps: extreme close-up

Neither of the images is perfect, but the x264 version retains more detail than the HEVC version. The HEVC output looks smoother, but this actually means that some important detail has been removed during encoding.

Here's another example, this time a close-up from a frame of the Racehorses sequence, originally 480p resolution:

x264 at 1.8Mbps : extreme close-up

HM10 at 960kbps: extreme close-up

Once again the x264 version retains more detail than the HEVC version. Notice the over-smoothed appearance of the horse's face in the HEVC / HM10 close-up.

HEVC will give a clearer, higher quality image than H.264 at the same bitrate. But is it really twice as good as H.264, i.e. does it give the same quality at half the bitrate? These still frames imply that HM10 does not perform as well as H.264 at half the bitrate. However, recent research by Wang et al indicates that HEVC has bigger performance gains for moving image sequences than for still images taken out of a sequence.

It's also worth noting that x264 is a highly efficient implementation of H.264 that has been optimized over a period of years. As HEVC and its implementations mature, we can expect improvements in performance and image quality.

I'll be posting more results soon and explaining exactly how to test this for yourself. To download the HM reference software, visit this page.

HEVC : how long before it hits the mainstream?

Analysts are beginning to argue about when HEVC will reach the mainstream market. Frost and Sullivan thinks that a critical mass of adopters could take 3 years and that it may be at least 5 years (2018) before consumers see widespread HEVC support in their electronic devices. On the other hand, Ryan Lawler of Techcrunch expects devices with HEVC support to become widely available in around 18 months, with rapid adoption thereafter.

Many chip manufacturers have been closely involved in the standardisation process for HEVC and are already gearing up for production of HEVC-compatible devices. Will the performance gains offered by HEVC be enough to prompt device manufacturers, service providers and users to switch over to the new standard? If so, how quickly will the shift happen? What do you think?

The HEVC standard has been approved

"Geneva, 25 January 2013 – A new video coding standard building on the PrimeTime Emmy award winning ITU-T H.264 / MPEG-4 AVC was agreed by ITU members today".

The ITU-T has announced approval of the new High Efficiency Video Coding (HEVC) standard. The new standard will be co-published as Recommendation ITU-T H.265 and ISO/IEC 23008-2.

HEVC is intended to be a successor to the popular H.264 / Advanced Video Coding standard, first published in 2003. As with every video coding standard, the performance of HEVC depends on the way it is put into practice. The developers of the standard, a consortium of ITU-T VCEG and ISO MPEG known as the Joint Collaborative Team on Video Coding, are expecting HEVC codecs to offer around twice the compression efficiency of H.264/AVC. That means approximately half the bandwidth for the same video quality.

You can download a draft of the HEVC standard and the reference software codec here.

- Iain Richardson

2 billion HEVC devices by 2016?

A market research report by MRG estimates that there will be more than 2 billion HEVC-compatible devices by 2016, with the biggest adoption rates likely to be in the mobile / internet market sectors. You can read the news release here.
HEVC (High Efficiency Video Coding) is the new standard for video coding, developed by ISO MPEG and ITU-T VCEG.

DASH and HEVC

A couple of useful overview articles:
MPEG DASH : dynamic adaptive streaming over HTTP (Jan Ozer)
The HEVC/H.265 wave : what it means for businesses (Randon Morford)

At IBC2012...

I'll be at this year's International Broadcasting Convention in Amsterdam, from 7th-11th September 2012. OneCodec will be sharing the Scottish Development International stand, 9.B26, and we'll be showcasing our new video sharing product, Beamshare. If you're interested in meeting up, let me know. - Iain