From the course: Producing Professional Audio and Video Podcasts

The need for compression

From the course: Producing Professional Audio and Video Podcasts

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The need for compression

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- When it comes time to deliver your podcast, audio or video, we need to compress them. This is removing information, while still preserving the key details. - In the photographic world, this is making a JPEG file when you shot Camera Raw. What we're trying to do here, is create something that's representative of the original file. But in reality, we're probably throwing anywhere from 90 to 98% of the information away. This process is referred to as Compression. And before I show you how to do it, I want to make sure you're familiar with some key terms. First term is going to be the Architecture. Architecture is the overall platform. This is the global classification of a file. So it's things like MPEG, Quicktime, Windows Media. Think of it as the big picture. Next is the Compressor/Decompressor also known as a Codec. The Codec allows you to shrink the files by using an Algorithm. The Algorithm is usually proprietary and involves some sort of licensing fee. Most of the software that you use will have paid this licensing fee. Some Compressors do cost extra money though. And there are ones that you could purchase or license for specialty things. Maybe you have to do delivery to certain platforms. Well, you might have to pay for that Codec. Want to make Apple Prowess. Well, you need to license it from Apple or by one of their apps to do so. These days, most modern Compression types are really effective. When I started creating video for the web, it was the mid 1990s. And back then, we were lucky to get postage stamps. And they were really, really bad quality. Now we're used to getting HD or even 4K videos streamed to our set top boxes in our television. And this looks great. And with podcasting, you could take advantage of this. Popular formats from the MPEG group, such as MPEG four or the newer H.625, have really allowed for things to come to play here. What's driving all of this though, is the Bit Rate. This is the amount of data per second. If you have Bit Rates that are higher, you tend to have a better looking image.. However, there are limitations. As you bump up the Bit Rate, you're going to increase the file size. Which increases the download. Additionally, not all of the playback devices can handle the higher bit rates. Something like a set top box, like an Apple TV or Roku, can often handle higher Bit Rates than something like a smartphone. Particularly an earlier smartphone. So there are settings recommended that are always a good idea. And you'll see these as web file Compression or web Bit Rate. On the audio side, we refer to the Sample Rate. This is very similar to Bit Rate for video, but it deals with the amount of audio samples per second. 48 Kilohertz is most commonly used when talking about digital video, but when we're making audio podcast files or web video files with audio, it's often 44.1, which is referred to as CD quality. The CD refers to Compact Disc, and it was the digital audio standard. Those are those shiny silver things that some of you still use to listen to music before downloads. Additionally, when it comes to Compression, we could have Variable Bit Rate Compression. This means instead of keeping a constant Bit Rate, throttle the Bit Rate. So as the visuals get more complex, use more data. As the visuals get simpler, like a screen cast that Photoshop tutorial where not much was moving. Well, the data can get pushed down. And with all of this, we look for Batch Processing. And trust me, Batch Processing is just like a good plate of cookies. You want to cook them several at a time. Video Compression can take a while and you don't want to have to set one thing up and then walk away and then come back and do the next thing. So when we're working with our tools, we often have the ability to queue up multiple items. You can load up multiple sequences into something like Adobe Media Encoder, or a Dragon multiple files with a tool like Apple Compressor. Pick the right settings, and that lets several things process. This is generally unsupervised work. Things that can happen while you take a lunch break, or while you go home for the evening. Let the computer do the work without you, rather than sit there waiting.

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