Preparing Video Files for Pulse
You can find our recommended settings in Creative Asset Specification.
Encoding Your Video Files
We have begun enforcing our creative specifications and limiting which files qualify to be used in our ad player. So, it is more important than ever that the video files you upload are correctly encoded. We do this to ensure that the files you upload are, beyond a doubt, viewable by your visitors. This becomes increasingly important as you start to deliver to different targets, like different computer browsers and mobile devices. Incorrectly encoded video files can lead to poor viewing quality, long download duration, or the video not being displayed at all.
You can use the free video encoding tool "Handbrake" to encode h.264 video. If you are familiar with other tools, our settings can be easily applied to your favorite one. You can downloaded Handbrake here.
Why do we need to encode?
The raw files used when recording and processing videos are massive and unwieldy. Before a video can be distributed to a TV, on a DVD, or over the net, the video files have to be compressed or encoded to obtain a video of an appropriate size and quality for each target. There are endless numbers of ways to encode video files, but a number of standard encoding techniques, or codecs have emerged and each target has its preferred codec and compression rate.
There are a large number of codecs but this article only covers those used to display ads using Pulse.
Flash and FLV
Flash has long been the method of choice for distributing video over the Internet and still dominates this market. Its proprietary file format, FLV, has long been the standard encoding format for video distribution over the Internet. The FLV file format contains video that can be encoded with the ON2 (VP6) codec or the older Sorenson Spark codec (not officially supported by Pulse). From the release of Flash version 9.0.115 (released December 2008), the Flash player also supports the H.264 codec (described below), which is more and more becoming the codec of choice for web distribution.
Today, there is no real reason to encode to the FLV file format unless you want to deliver very small files at low resolution. In this case, FLV still delivers a better quality/size ratio. That said, there is no reason to re-encode FLV files to H.264 unless you want to specifically target a HTML5 video player.
H.264 (MP4, M4V, F4V)
The most dominant codec for high-resolution video on the internet today is H.264, which is part of the MPEG-4 family. H.264 is a codec which can be stored in several different types of container file formats, such as MP4, M4V, F4V. Although these file containers may work in most situations with Pulse, we recommend, and only officially support, the use of the MP4 container.
The H.264 codec can be used for Flash players and HTML5 video players. Devices such as the iPhone or iPad that cannot run Flash are dependent on video being encoded with H.264. H.264 running in an HTML5 video player is supported by the Internet Explorer 9+, Chrome 3+, and Safari 3.1+ browsers. Unfortunately, it is not currently supported on any default configuration of Firefox or Opera.
HTML5 video players that want to deliver to browsers like Firefox and Opera, which dominate almost a fourth of the market, must offer an alternative encoded video. Theora is an open-source video codec that uses the Ogg file format and is compatible with the Firefox 3.5+, Chrome 3+, and Opera 10.5 browsers. Safari is supported if the user installs a plugin, but Internet Explorer is not supported. Flash does not support Theora.
WebM (VP8) is an alternative to the Theora codec . WebM is a free open-source video codec sponsored by Google and aspires to be the HTML5 standard for video. WebM uses the WebM file format (.webm) and is compatible with FireFox 4, Opera 10.6 and Chrome. Internet Explorer supports WebM if a plugin is installed, and Safari can play the video through Quicktime only if a third party plugin is installed. Adobe Flash does not support the WebM codec.
- The bitrate for video can range from 100 kbps to 20000 kbps (and more) dependent on the resolution of the video (height and width), the codec, frame rate, and the desired quality. Video for Internet often ranges from about 300 kbps for slow connections to 2500 or 3000 for fast connections.
- The bitrate for sound spans from 320 kbps for CD quality music to about 32 kbps for normal speech. The bitrates 128 and 160 kbps are often used for MP3 music files and video for the Internet.
It is often recommended to use the same frame rate as the source video otherwise blurring and other rendering issues can appear when the encoder tries to interpolate uneven frames.
The resolution, or width and height of the video, has a large impact on the bitrate needed to produce good quality video. That said, video usually presents better when encoded with a high resolution and low bitrate than when encoded with low resolution and high bitrate, especially when shown in fullscreen. The challenge is to find the "Goldilocks zone" with good quality video and small file sizes.
Now, it is time to actually do some encoding! Handbrake can only be used to encode H.264. To encode FLV or Theora please use other video encoder.
- Open Handbrake.
- Set the video encoding settings.
- Set the audio encoding settings.
- Set the picture settings (video resolution).
- Press start to encode.