Video Formats and Bombardment Life

Now that we've established at that place's an axiomatic delta in efficiency among a small group of popular media players, it'south time to look at formats. All the previous testing was performed using a H.264 video sample, which is arguably the most popular video format at the moment, but at that place are loads of other formats people employ. So which one will give you the best bombardment life?

Theoretically, whatsoever format that can be hardware accelerated will give a sizable battery life advantage, every bit GPUs tend to exist more than efficient at these tasks than the CPU. On top of this, a codec that compresses to a lesser degree should be more battery life friendly, and lower resolutions will be advantageous every bit well.

All of these come up with trade-offs though. Less compression equates to a larger file size, which on devices with express storage means fewer videos tin can be stored. In a streaming situation where bandwidth is fundamental, the lower bitrate, the improve. Lower resolutions both subtract file size and are easier to decode, but quality will inherently endure. In a world where Hd is the new norm and 4K is up and coming, no one actually wants to go back to 480p for efficiency's sake.

H.264 is the chief format I tested with, in four unlike configurations. First is the 720p file I used for testing on the previous page, the second a typical 1080p sample with a moderately loftier bitrate; both files had 6-aqueduct audio. The third file was a 1080p sample at sixty frames per second, which tin can cause devices to stress out more during the decoding procedure, and fourth, a compressed 4K (2160p) video.

I chose 2 older formats to examination with: Xvid and WMV. Both formats are typically hardware accelerated; the Xvid sample was 720p and comparable in bitrate to the 720p H.264 sample, and the WMV sample is standard definition. Just on visuals, H.264 delivers better quality for the bitrate compared to Xvid, so it'll exist interesting to see how they compare in battery life.

Adding to the mix is a new, loftier compression, high quality format that is sure to increase in popularity in the next few years as companies look to push button loftier-resolution content through limited bandwidth pipelines. Known as HEVC, it's essentially the successor to H.264, and tin can be known equally H.265 in some circles. As the format is relatively new, it tin't be hardware accelerated, but videos encoded in HEVC look absolutely astonishing for the bitrate used.

The last format I thought would exist interesting to test with is Planar YUV with four:4:four chroma subsampling. This video is uncompressed (lossless), delivering the highest possible quality with massive file sizes. The item sample I used was 720p, 50 frames per 2d and had a whopping bitrate of i.1 Gbps, creating a 1.3 GB file from only 10 seconds of footage.

You can meet the full specifications of each video sample in the table below.

Format Container Resolution Frame
Rate		 Video Bitrate Audio Type Audio Bitrate Total Bitrate
H.264 .mp4 1280 x 720 24 2.i Mbps 6ch AAC 400 kbps 2.5 Mbps
H.264 .mp4 3840 x 2160 24 19.four Mbps 2ch AAC 190 kbps xix.6 Mbps
H.264 .mp4 1920 x 1080 60 six.0 Mbps 2ch AAC 190 kbps half dozen.2 Mbps
H.264 .mt2s 1920 x 1080 24 viii.2 Mbps 6ch AC3 640 kbps 8.8 Mbps
HEVC .ts 1920 x 1080 24 1.seven Mbps 2ch AAC 70 kbps 1.eight Mbps
Xvid .avi 1280 x 720 24 2.i Mbps 6ch AC3 450 kbps ii.vi Mbps
WMV .wmv 640 x 480 30 2.0 Mbps 2ch WMA 130 kbps ii.ane Mbps
YUV 4:four:4 .y4m 1280 x 720 50 1,100 Mbps None None 1,100 Mbps

For benchmarking video formats I stuck to the Lenovo Miix 2 eight with its Bay Trail innards, performing each test under the same weather as before. Bay Trail is a skillful platform to exam with as it supports hardware decoding, is plant in the bulk of Windows tablets on the market place, and is mostly a solid performer both in battery life and low wattage processing power. I wouldn't expect relative results to differ greatly betwixt Bay Trail and Haswell or Ivy Span.

Here's what I discovered through my testing of unlike formats.

Over again, we're seeing a massive gulf in between the almost efficient and least efficient format I tested: 720p H.264 delivered a massive 120% longer stint on battery than 1080p HEVC. As it turns out, the format I tested with in the first department is the nearly efficient overall, although I'd expect if you reduce the resolution down to 480p while encoding in H.264 you'd get an fifty-fifty better upshot.

Just looking at H.264-formatted videos, the resolution and frame rate can have a pregnant effect on battery life. Going from 720p to 1080p caused a 10% drop in battery life, equating to effectually an hour drop in the conditions I tested with. If you tin tell the deviation in quality between 720p and 1080p, the decoding efficiency decrease is worth it, although on the Miix 2 8's WXGA display I'd rather encode my videos in 720p to get the longest battery life out of the device.

Having videos encoded in 4K (2160p), or 1080p at 60 frames per 2d, is unlikely, and both formats provided a larger subtract in battery life. At 4K, you can look a drop in expected battery life of effectually 28% and 19% coming from 720p and 1080p respectively, which isn't as huge every bit I was expecting. Equally you lot can see from the graph above, 1080p60 is a similar story.

The high-compression HEVC format can simply be decoded in MPC-HC and VLC, and most fleck architectures are incapable of decoding it efficiently as it'southward and then new. While it delivers fantastic quality for the file size, information technology'southward impractical for a battery-powered device when it lasts half equally long equally an equivalent-resolution H.264 file.

Uncompressed video is another interesting instance: the processor doesn't need to practice whatsoever decompressing of the stream, only the enormous bitrate puts a lot of strain on memory bandwidth and GPU capabilities. As such, information technology also performs poorly when measuring battery life.

Looking at CPU usage in the most efficient setup – that is, using the Videos app for all formats except HEVC and lossless, which were run in MPC-HC – reveals some interesting things. HEVC utilizes 100% of the CPU to decode, while 720p Xvid (H.263-based) is surprisingly CPU intensive compared to H.264. In that location is as well piffling difference between 4K and 1080p H.264 decoding, suggesting differences in battery life are downwards to higher GPU usage.

Checking CPU usage for a 720p H.264 sample across all the video players I tested shows utilization anywhere between 3% and 22%. Results hither correspond perfectly to what player is the most and least efficient.

Final Thoughts

If these tests have taught us anything, the video player you lot utilize and the format of your video is critical to achieving the longest battery life. A combination of a 720p H.264 video played in the stock Windows 8 Videos app gave the longest battery life out of those that I tested, although using 1080p or 4K resolutions tin give much improve quality with just a small subtract in stamina.

Unfortunately it'south not always possible to watch solely H.264 videos; sometimes you'll become i in a MKV container, sometimes you lot'll become a less-efficient Xvid file, and others you'll take to deal with crazy formats. Power Media Player is capable of playing a wider range of formats than the Videos app in an efficient manner, simply it's non gratis and nor does it carry features you become from gratis alternatives such as VLC.

Popular free alternatives like VLC and MPC-HC aren't as efficient as you might await. Choosing to play a video in VLC over the stock Videos app effectively results in three less hours of playback time, which is far from ideal. While these apps do support the largest range of formats, and have many useful features, the decoding efficiency needs to ameliorate so they're worth using in basic playback situations.

Finally, while HEVC is past far the nearly impressive format in that it provides astonishing quality with a low bitrate, it's extremely resources intensive to decode, especially on relatively weak tablet hardware. Until nosotros get efficient hardware decoding for the format in future platforms, it's unlikely we'll run into information technology overtake H.264 as the near popular video format.