Video Formats and Bombardment Life

At present that we've established in that location'southward an evident delta in efficiency amongst a small grouping of popular media players, information technology'due 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, just there are loads of other formats people use. So which i will give yous the best bombardment life?

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

All of these come with merchandise-offs though. Less compression equates to a larger file size, which on devices with express storage means fewer videos can be stored. In a streaming situation where bandwidth is key, the lower bitrate, the better. Lower resolutions both decrease file size and are easier to decode, but quality will inherently suffer. In a world where Hard disk is the new norm and 4K is up and coming, no ane really wants to get back to 480p for efficiency's sake.

H.264 is the main format I tested with, in four different configurations. First is the 720p file I used for testing on the previous page, the second a typical 1080p sample with a moderately high bitrate; both files had 6-channel audio. The third file was a 1080p sample at threescore frames per 2nd, which can crusade devices to stress out more during the decoding procedure, and fourth, a compressed 4K (2160p) video.

I chose ii older formats to test 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. Only on visuals, H.264 delivers better quality for the bitrate compared to Xvid, and then information technology'll be interesting to see how they compare in bombardment life.

Adding to the mix is a new, high compression, loftier quality format that is sure to increase in popularity in the adjacent few years every bit companies look to push high-resolution content through express bandwidth pipelines. Known every bit HEVC, it'due south substantially the successor to H.264, and tin be known as H.265 in some circles. Equally the format is relatively new, it tin can't be hardware accelerated, but videos encoded in HEVC await admittedly amazing for the bitrate used.

The last format I thought would be interesting to test with is Planar YUV with 4:4:4 chroma subsampling. This video is uncompressed (lossless), delivering the highest possible quality with massive file sizes. The detail sample I used was 720p, 50 frames per second and had a whopping bitrate of 1.1 Gbps, creating a 1.3 GB file from merely 10 seconds of footage.

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

Format Container Resolution Frame
Rate		 Video Bitrate Sound Type Audio Bitrate Total Bitrate
H.264 .mp4 1280 x 720 24 two.1 Mbps 6ch AAC 400 kbps ii.five Mbps
H.264 .mp4 3840 ten 2160 24 nineteen.4 Mbps 2ch AAC 190 kbps nineteen.vi Mbps
H.264 .mp4 1920 x 1080 sixty 6.0 Mbps 2ch AAC 190 kbps six.2 Mbps
H.264 .mt2s 1920 x 1080 24 eight.2 Mbps 6ch AC3 640 kbps 8.8 Mbps
HEVC .ts 1920 ten 1080 24 1.7 Mbps 2ch AAC 70 kbps 1.8 Mbps
Xvid .avi 1280 x 720 24 2.1 Mbps 6ch AC3 450 kbps 2.half-dozen Mbps
WMV .wmv 640 x 480 30 2.0 Mbps 2ch WMA 130 kbps 2.ane Mbps
YUV 4:4:4 .y4m 1280 x 720 fifty 1,100 Mbps None None ane,100 Mbps

For benchmarking video formats I stuck to the Lenovo Miix two viii with its Bay Trail innards, performing each examination under the same weather condition as earlier. Bay Trail is a skillful platform to examination with equally it supports hardware decoding, is found in the majority of Windows tablets on the market place, and is generally a solid performer both in battery life and depression wattage processing power. I wouldn't expect relative results to differ greatly between Bay Trail and Haswell or Ivy Bridge.

Here'southward what I discovered through my testing of different formats.

Once once more, we're seeing a massive gulf in betwixt the most efficient and to the lowest degree efficient format I tested: 720p H.264 delivered a massive 120% longer stint on bombardment than 1080p HEVC. As it turns out, the format I tested with in the get-go section is the most efficient overall, although I'd wait if you reduce the resolution down to 480p while encoding in H.264 yous'd get an fifty-fifty meliorate effect.

Only looking at H.264-formatted videos, the resolution and frame rate tin can have a meaning effect on battery life. Going from 720p to 1080p caused a 10% drop in battery life, equating to around an hour drop in the conditions I tested with. If you can tell the difference in quality betwixt 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 second, is unlikely, and both formats provided a larger decrease in bombardment life. At 4K, yous tin can expect a drib in expected battery life of around 28% and 19% coming from 720p and 1080p respectively, which isn't every bit huge as I was expecting. As yous can come across from the graph to a higher place, 1080p60 is a like story.

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

Uncompressed video is another interesting case: the processor doesn't demand to practise any decompressing of the stream, but the enormous bitrate puts a lot of strain on memory bandwidth and GPU capabilities. As such, information technology too 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. There is besides little difference betwixt 4K and 1080p H.264 decoding, suggesting differences in battery life are down 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 role player is the nearly and least efficient.

Final Thoughts

If these tests have taught united states anything, the video player you lot use 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 can give much improve quality with only a small subtract in stamina.

Unfortunately information technology'southward not always possible to scout solely H.264 videos; sometimes you'll get 1 in a MKV container, sometimes you'll get a less-efficient Xvid file, and others you'll take to bargain with crazy formats. Ability Media Player is capable of playing a wider range of formats than the Videos app in an efficient way, but it'due south not gratis and nor does it carry features you go from free alternatives such equally 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 finer results in three less hours of playback time, which is far from platonic. While these apps do support the largest range of formats, and have many useful features, the decoding efficiency needs to better so they're worth using in basic playback situations.

Finally, while HEVC is by far the near impressive format in that it provides astonishing quality with a depression bitrate, information technology's extremely resource intensive to decode, specially on relatively weak tablet hardware. Until we get efficient hardware decoding for the format in future platforms, it'south unlikely we'll see information technology overtake H.264 every bit the almost popular video format.