HEVC Tutorial and Video Walkthrough

I've posted the first in a series of tutorials and resources for the new HEVC (High Efficiency Video Coding) standard.

1. An introduction to High Efficiency Video Coding (summary version)

2. An introduction to High Efficiency Video Coding (full version): coming soon

3. HEVC walkthrough: taking you through some of the features of HEVC using the Elecard HEVCAnalyzer (Vimeo).

High Efficiency Video Coding (HEVC) Walkthrough by Vcodex from vcodex on Vimeo.

Comments and feedback are always welcome.

- Iain

Visiting Washington DC in May...

I'll be visiting Washington DC from 20-24 May 2013. If you're based in the area and are interested in meeting up to talk about video compression, HEVC, intellectual property or anything else, please drop me a note.

- Iain Richardson, iain@vcodex.com

Comparing HEVC and H.264 quality: see for yourself

Now that the GPAC / Osmo4 player supports HEVC decoding and playback, it's becoming easier to compare the quality of the new High Efficiency Video Coding (HEVC) standard with its predecessor, H.264/AVC. I've uploaded three versions of the same sequence:

a. Encoded using HEVC / HM10

b. Encoded using H.264 / x264 at twice the bitrate of a.

c. Encoded using H.264 / x264 at the same bitrate as a.

To compare H.264 and HEVC / H.265:

1. Download and install the latest version of GPAC, which includes the Osmo4 player:

http://gpac.wp.mines-telecom.fr/downloads/gpac-nightly-builds/
(Choose Latest Available Binaries)

2. Download the following test sequences:

a. Kristen and Sara, 720p, 10 seconds, 60 frames per second, HEVC / HM10 Anchor (Random Access, QP=32), approx 420 kbps.

https://www.box.com/s/hrbj7pd2vpdpfynm7xdu

b. Kristen and Sara, H.264 / x264 / veryslow preset, QP=31, approx 810 kbps. https://www.box.com/s/is2sdqh7tqdiuc1i76g6

c. Kristen and Sara, H.264 / x264 / veryslow preset, QP=37, approx 440 kbps.

https://www.box.com/s/3mkoob6sppijp2b1kf3g

3. Play back each test sequence using the Osmo4 player.

Things to look out for:

- At the same bitrate (~420kbps), is the quality of the HEVC sequence (a) significantly better  than the H.264 sequence (c)? In my view, yes.

- At half the bitrate (420kbps vs. 810kbps), is the quality of the HEVC sequence (a) as good as the H.264 sequence (b)? In my view, the HEVC sequence displays smoother motion, but loses some fine detail.

To experiment with other test sequences:

1. Download + install GPAC, as described above:

http://gpac.wp.mines-telecom.fr/downloads/gpac-nightly-builds/
(Choose Latest Available Binaries)

This package includes the Osmo4 player and the MP4Box utility.

2. Download an encoded HEVC anchor bitstream (.bin) from:

ftp://ftp.kw.bbc.co.uk/hevc/hm-10.0-anchors/bitstreams/
(I chose "Kristen and Sara, QP=32" from the Random Access folder for the above examples).

3. Rename the downloaded bitstream: from (name).bin to (name).265

4. Package as an .mp4 file. Open a command prompt and type:

mp4box -fps (fps) -add (name.265) (name).mp4

- where (name.265) is the renamed bitstream file and (fps) is the number of frames per second of the original sequence.

(Here's an example of the command line for the Mac, your path may be different: /Applications/Osmo4.app/Contents/MacOS/MP4Box -fps 24 -add Kimono1_qp32.265 Kimono1_qp32.mp4)

5. Open with Osmo4 and play back.

Notes

Windows: Playback of 720p HEVC sequences is a little jerky but works reasonably well. Playback of higher-resolution sequences is very jerky on my PC.
Mac : Playback of 720p and 1080p HEVC clips on my Mac (10.8.3, 2.9GHz) is reasonably smooth.

Quality is subjective

Video quality is, of course, highly subjective. I'm interested in your feedback. Do you think the 420kbps HEVC sequence (a) is as good as, or better than, the 810kbps H.264 sequence (b)?

- Iain Richardson

Busy day in Washington DC yesterday...

Giving evidence at the US International Trade Commission in the morning and visiting the US Patent and Trademark Office in the afternoon. Very impressed by the USPTO - over 10000 patent examiners and support staff, in a campus that's bigger than many Universities, dealing with thousands of applications per month.

- Iain.

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?