Performance
Let's compare the performance of video playback on the current MID platforms. The first test compares the playback performance with Totem player on a Compal Jax 10 MID platform. The Intel GMA 500 chipset used in this MID is the UL11L. The Intel Atom processor is the Z500 at 800 MHZ. In this test we will limit ourselves to SD content as the UL11L chipset is not supporting HD content decode.
The measurements taken below are measuring the CPU usage of a full video playback including audio decode. The first measurement shows the system cpu usage when doing a playback on Totem player with the software FFmpeg codecs (no hardware acceleration). The second one shows the system CPU usage when doing a playback on RealPlayer for MID with the hardware accelerated codecs.
The usage of the VA API allows the CPU usage to drop significantly when the hardware video decode is used reducing significantly the power drain on the battery. Note that when the CPU reaches 100% the system is not capable anymore to match the targeted frame rate. Indeed, the frame rate drops to a few frames per second, giving a pretty degraded experience.
In the second test we will use a platform with an Intel Atom processor Z530 at 1.6GHZ and a US15W GMA 500 chipset. Unlike in the previous test, this version of chipset is capable of decoding HD content. The playback is done with the regular FFmpeg codecs (without hardware acceleration) and the second one with the Fluendo codecs using hardware acceleration through the VA API. Note here that we are only measuring pure video decode. There is no audio decode happening.
The playback has been activated here using gst-launch-0.10 tool with the following command line :
gst-launch-0.10 filesrc location=<media file> ! decodebin ! queue ! xvimagesink
The system had Intel Hyper-threading Technology disabled. When reaching 100% usage, the playback experience is significantly degraded as the encoded fps cannot be delivered by the system. It drops to a few frames per second making the experience pretty poor.
Summary
As MIDs are becoming more and more widespread, video playback on this devices is seen as one of the major usage model especially as mobile TV and Video on Demand are really becoming popular. To be able to experience video playback in optimal conditions and to extend the battery life of the device, it is essential that the video players are using the hardware video decode capability provided in the platform.
Independent software vendors (ISV) have the choice to build their players on top of multimedia frameworks optimized for such platforms as Helix or Gstreamer, or to implement this decoding using the standard public API: VA API. It's a tremendous opportunity to get into this new growing segment and bring outstanding video support to the handheld world.
Acknowledgements
Special thanks to Jonathan Bian and Sengquan Yuan for their contribution to this article.
