Encoding videos in general is a very confusing topic since one has to understand and have a lot of technical knowledge about encoders and decoders and the multitude of video formats. To further complicate matters tools such as Adobe Premiere Pro C3 make the job even more confusing with a multitude of presets out of the box, none of which seem to really apply to what most of us are trying to do.
Essentially, you’re either trying to encode a video for the Internet or for DVD/Blu-ray production. Your source video is either SD or HD. This article is written for those whose source video is HD and the intent is to publish videos to video hosting websites that support HD videos such as ExposureRoom. For DVD/Blu-ray I’ve found Adobe Premiere Pro CS3’s default presets pretty good.
Encoding for the Internet
I believe most people reading this blog want to encode videos for the web these days since it’s a very effective delivery mechanism and website’s such as ExposureRoom retain the HD quality of the source video making it viable to show off your productions to customers and prospective customers as well as family and friends.
You might want to take a look at my Videos.
Deinterlace
In the Export Settings dialog in Premiere Pro C3, switch to the “Output” tab (top left hand side of the dialog) and ensure that the Deinterlace check box is checked. This should be check by default, but make sure in any case.
Format
I’ve found that the Adobe Flash Video format renders the best contrast and color saturation. Quick Time videos tend to look the most faded, while the Window Media format is in between. Be aware that in order to play Adobe Flash Video files, you’ll need a Flash Video player (Not Flash Player, but Flash Video Player). If you need your raw videos (meaning you’re making your encoded files available directly via an FTP site or similar) playable on a PC as well as MAC, you should encode in Quick Time format, unless you’re providing the Flash Video player as well.
Dimensions
Most video players perform best when the dimensions of your video are multiples of 16. I’m not going to get into the technical details behind this here, but just remember that. So you’re wondering why the 1080 HD dimensions (1920x1080) are not multiples of 16, right? Well, that’s because HD was not made for computers and when I said video players earlier I meant computer video players (Adobe Flash Video Player, QuickTime, Window Media Player etc.). Having said that, don’t be hell bent of this rule. It’s a good rule to know and to stick to when you can but it’s not a must.
Video Bit Rate
The Video bit rate is by far the most important from a quality stand point. It’s also almost entirely responsible for the physical size of the encoded video file. And you thought the dimensions would play a part too didn’t you? Dimensions do play a part, but an insignificant part. You can see for yourself by encoding the same source video to two different dimensions and keeping the video bit rate the same (and all other settings the same).
Too high a video bit rate can also be detrimental. For instance if you plan to make your videos available for download to your customers and friends and because you want them to see the best quality you encode your videos with say a video bit rate of 8,000. Some of your customers will be able to view the video while others may not. In general, a video with a higher bit rate requires a faster computer. You see in order to played back the video the player needs to decoded it while it’s being played back and the more bits the player has to decode per second the more work it has to do. A video encoded with a higher bit rate needs to be decoded at a higher bit rate as well. So if the video is jerky, it’s more than likely that the computer can’t handle the bit rate.
Even DVD players have a limit to the bit rate they can handle. This limit is usually 9,800. But this limit includes the audio bit rate as well. More about audio bit rate next.
There are two factors that really determine the video bit rate you should use:
1. The dimensions of the video – Larger the dimensions, the higher the bitrate should/may need to be.
2. Movement in the scene – If there is a lot of movement (especially fast movement) or a lot of panning or tilting, you’ll need to encode using a higher bit rate in order to make the video look decent and not be jerky.
CBR, VBR 1 Pass, VBR 2 Pass
This is another complicated topic. Suffice it to say that 99% of the time you should use VBR 2 Pass. VBR in general takes more time to encode and VBR 2 pass takes even more time to encode. VBR 2 Pass produces the smallest files. CBR tends to be the fastest to encode but produces larger files. If you’re burning a DVD or Blu-ray and you have more than enough room on the disk you can encode your video as CBR. VBR also taxes the playback computer more than CBR does.
Audio Bit Rate
By now you’ve probably figured out that bit rate is directly proportional to quality. And the size of the file is directly proportional to quality as well. And you’d be correct. Encoding is therefore a fine balance between quality and file size. Typically an audio bit rate of 224 is pretty decent (Close to CD quality) and most viewers won’t notice any loss is audio quality. Most MP3 download sites encode their audio files at 128 kbps. So if that quality is good for you then choose an audio bit rate of 128. Don’t try and encode at a higher bit rate than the original source audio, since that has no meaning. You’ll get a bloated file with no increase in audio quality. So the best thing to do is find out the source’s audio bit rate first and accordingly decide the audio encoding bit rate you should use.
HD Video encoding for Internet
Well a lot depends on the website you intend to upload your video to. YouTube will massacre your videos so encoding using a high bit rate (both audio and video) has no meaning.
ExposureRoom supports HD video and allows playback at 720p. So keep your dimensions at 1280x720 and encode your videos at 4,500kbps - 5,000kbps, with an audio bit rate (if the source audio bit rate supports it) between 128-224 kbps. If you decide to encode your videos at a dimension of 1920x1080 you will have to more than double the video bit rate and that will more than double the resulting file size.
If you’re making your original files available for download, such that the viewer downloads the file to their computer first and then views them, keep in mind that even though a lot of people have high-speed internet access and wouldn’t mind waiting 20-30 minutes to download your videos, their computers may not be able to handle videos encoded at a very high bit rate. I’ve found a video bit rate of 5000kbps is a good limit to stick to.
If you’re making your videos available by embedding a video player such as QuickTime or Windows Media Player in a web page then keep the following in mind:
In order for a viewer to be able to view your video almost as soon as they click on the play button your video will need to be encoded with a maximum bit rate (audio video) that is less than their download rate. For most home users this is around 384 to 768 kbps.
