Zencoder Guide to Encoding for Quality


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Steve Jobs once remarked: “(One should) be a yardstick of quality. Some people aren’t used to an environment where excellence is expected.” These days it seems that everyone has caught on to Mr. Jobs’ ideal of an excellent experience.

Learn how to deliver the best online video experience every time, no matter what device or connection your users are on.

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Zencoder Guide to Encoding for Quality

  1. 1. Encoding for QualityHow to Deliver the Best Online Video Experience Every TimeThere’s no excuse for poor-quality online and mobile video. With the rapidevolution of online video technology and standards in recent years, everyvideo played on any desktop, mobile, or connected TV platform should lookand sound great every time. With expectations raised by HDTV, Blu-Ray,and premium online content, that’s exactly what consumers have come todemand. If your online video experiences can’t meet their standards, you’llstand out in all the wrong ways.To succeed with online video, you need to make first- and second-generation iPads, 1920 x 1080sure your videos look just as good to viewers as or third-generation iPads, and so on) within thethe best available offline video. The following parameters of your source content, along withrecommendations can help you provide the best lower resolutions for users with lower bandwidth.possible experience no matter how or where We don’t recommend using your encoder toconsumers view your video content. upscale video, as this generally increases its size without really improving quality—properly1. Encode video to the highest quality scaling video is something that can be handled by the end device.for each device.Consumers use a wide variety of devices to playyour video, from iPhones, iPads, and Android- Brightcove’s Zencoder video encoding servicebased mobile devices to Roku, Xbox 360, and defaults to the H.264 Baseline profile at level 3.0connected TVs—each supporting different for the broadest possible device compatibility,types of video. A one-size-fits-all approach but allows you to choose other profiles andto encoding will inevitably compromise the levels via the API to ensure that you deliverexperience you deliver to many viewers. Instead, the best experience each device is capable ofmake sure you deliver video to each device in presenting. Most devices today support Mainthe highest quality it can handle. For example, and High Profile, for example, and these profileswhile most devices can handle the H.264 provide significant improvements to encodingBaseline profile, consumers who’ve invested quality.in more powerful devices like the latest iPad,PlayStation, and Xbox models can expect even 2. Use an adequate bitratebetter experiences delivered through the H.264Main and High profiles. The bitrate at which you deliver video can be even more important than the codec you use. After all, any codec can look good if youSimilarly, avoid upscaling or downscaling use enough bits. The right bitrate for eachvideo unnecessarily. You should deliver the top viewer depends on their bandwidth; the sameresolution for each device type (1024 x 768 for bitrate can be too low for viewers with ample 1
  2. 2. bandwidth, resulting in sub-optimal quality, the world’s most powerful encoding platform.but too high for viewers with lower bandwidth, Zencoder also provides the best availableleading to excessive buffering. The only way encoding technology at the format level; forto ensure the right bitrate for each viewer is example, Zencoder HLS packaging is 10 – 12through adaptive bitrate streaming: video is percent more efficient than other encoders,encoded at multiple bitrates, then delivered in resulting in smaller file sizes leading to lowerthe right bitrate for each viewer according to CDN and storage costs.their local bandwidth and device capabilities. 4. Don’t overlook audioZencoder provides complete cloud-based Audio quality is at least as important as video.encoding for adaptive bitrate protocols including A study by Ralf Steinmetz shows that it is “moreApple’s HTTP Live Streaming (HLS) and important to maintain a continuous (minimumMicrosoft Smooth Streaming to dynamically jitter) audio stream than a video stream” whenadjust video quality based on available watching video online (see also this article).bandwidth speeds. Similar studies have shown just how sensitive users are to audio/video desynchronization,3. Use the best available finding that viewers are sensitive to audio/videoencoding technology sync errors of just a few milliseconds. In another study, viewers who watched television with highVideo quality isn’t entirely determined by the fidelity stereo audio “liked the program contentcodec used; the same codec can look very significantly more and found it significantly moredifferent depending on how it’s encoded. When involving” than viewers watching the same videoH.264 was introduced back in 2003, it didn’t with low fidelity, mono audio.look much better than what had come before,and it took time for encoders to implement allthe features and optimize the efficiencies that The differences between good and bad audiowould unlock its full potential. H.264 has come a encoders are even more pronounced than thoselong way since then, becoming as much as two among video encoders. The AAC audio codec,times more efficient in some implementations. offering higher efficiency than MP3, has becomeThe same will be true for H.265 when it arrives; it the dominant choice of video publishers—butoffers the possibility of doubling the efficiency of many fail to ensure that it actually delivers theH.264, but it’ll take time to get there. Whatever quality of experience that it should. Publisherscodec you use, make sure you also take the time often opt for open source encoders for audioto choose the best encoder. and video, but the only production-ready open source AAC encoder, FAAC, hasn’t beenWhile the relative merits of H.264 encoders updated in two years, and its quality is generallyare a constant topic of debate, x264, a free recognized to be poor.software library for encoding video into H.264/MPEG-4 AVC format, has emerged as the best Zencoder uses the best commercial AACencoder in terms of quality, as shown in various encoder on the market, and supportscomparisons over the years from its introduction advanced profiles like HE-AAC and HE-to the present. The ongoing introduction of new AACv2, which deliver high quality sound atfeatures in x264 continue to enhance the quality low bitrates. Advanced audio processingand efficiency available through H.264, while techniques and algorithms further enhancecompeting video formats fall short. quality, so that even when comparing different implementations of the same encoder, Zencoder audio often sounds better.Zencoder’s massive speed and scalabilitycomplements the efficiency of x264 to provide 2
  3. 3. 5. Encode from high-quality content > Content that is sideways or upside-down is automatically rotated.Remember the old saying: garbage in, garbageout. The best codecs and software in the world > Operations are always performed in thecan’t help bad input. In fact, encoding bad video correct order for best results, such asmakes it look even worse, as the encoder tries deinterlacing video prior to resizing, not theto preserve artifacts and blockiness. Encoding other way around.good video is also a lossy process, but youcan minimize generational loss and ensure thebest results by starting with the best possible For viewers and publishers alike, this will besource content. Input your video at the highest a golden age for online video. More viewersavailable rendition and high enough bitrate to than ever are embracing the convenience,make the most of each viewer’s playback device flexibility, and mobility of watching content viacapabilities. the web rather than traditional broadcast or Blu-Ray platforms. It’s also never been easier to ensure a high-quality experience on anyZencoder helps publishers start from high- device people use. But outstanding online videoquality source content by charging for doesn’t happen automatically; you have to maketranscoding by the minute of output video sure you’re going about it the right way. Thetranscoded, not by the gigabyte. Charging recommendations above can help you deliverby GB can penalize publishers for uploading a the quality your audience demands every time.high-quality input, while charging by the minuteallows publishers to upload a high quality input,and eliminates having to choose between costand quality. ENSURING A QUALITY VIEWER EXPERIENCE6. Avoid common mistakes • Encode video to the highest qualityZencoder helps publishers avoid common for each device.encoding errors by performing operations in theright way, in the right order. • Use an adequate bitrate • Use the best available encodingFor example: technology> Changing the frame rate of your video • Don’t overlook audio results in dropped or duplicated frames, with noticeable and distracting results for • Encode from high-quality content the viewer. When changing the frame rate is necessary for bandwidth purposes, Zencoder can do so only by even multiples—such as AVOIDING COMMON MISTAKES going from 60 fps to 30 fps, or 30 fps to 15 fps—to avoid these problems. • Change your frame rate only by even multiples--or, preferably, not at all.> When source content in formats such as analog or 1080i HDTV needs to be • When necessary, deinterlace source deinterlaced, Zencoder uses the best available content before encoding video, not after. deinterlace algorithm, and completes this task before encoding video for best results. • Auto-rotate mis-oriented content. • Perform operations in the correct order.CONTACTsales@zencoder.com 3zencoder.com