Codec basics for Windows Premiere- Part 1
Disclaimer
Advanced users of Premiere may find that the codec recommendations in this tutorial to do not produce the best results for them. This tutorial is designed to assist beginning users in avoiding and correcting common problems with codecs.
Codec Introduction
Video files are really large. A standard NTSC frame is 720 x 480 pixels. Each pixel is composed of 3 bytes, one for each basic color in RGB. NTSC is 29.97 frames per second. Doing all the math, each frame of uncompressed NTSC video is about 30 MB for each second of video or 1.5 GB per minute of video.
Codecs do COmpression to reduce file sizes and DECompression to make the video viewable and usable. Reducing file sizes is good because the files take less disc storage space and reduce processor and computer bus requirements but compression does discard information and causes loss in quality. The amount of compression and the degree of loss in quality is dependent on the codec and which optional parameters that control the compression are used.
Rather than provide a complete discussion of codecs, this discussion of codecs will focus exclusively on what codecs to use with Premiere Windows version and how to identify a codec problem and sometimes fix a codec problem.
Codecs used during video editing are designed to maximize quality, so that quality does not degrade during editing. Codecs designed for creating final video, such as DVDs, Internet video, etc., are designed to reduce file sizes and meet playback device standards. Probably the most important thing to know about codecs is that codecs used for video editing should not be used for final video and codecs designed for final video should not be used for video editing whenever possible. The results of using a codec for a purpose it is not designed for frequently results in black video within Premiere or unacceptably large file sizes.
DV-AVI NTSC or DV-AVI PAL. Just use either PAL or NTSC depending on which system is used in your county. NTSC is used in North America and PAL in Europe. What could be simpler? You know all those choices you get from Premiere when initially starting Premiere? Ignore them 99% of the time. The other 1% are used when importing projects from older versions of Premiere or from other sources of video. The DV definitions are designed to match exactly the video coming in from your camcorder and use it with minimal quality loss.
The default codec used with DV-AVI is provided by Microsoft as part of Windows. This is the correct codec to use with DV-AVI most of the time. Both Canopus and Pinnacle sell capture cards that are designed to be used with Premiere. These capture cards include codecs that are integrated with the capture cards to provide hardware assist (faster speed) for codec operations than the default Microsoft codec, along with other features. Also some software vendors, such as MainConcept, provide codecs that are intended to perform better than the Microsoft DV-AVI codec. The codec to be used with DV-AVI is identified in the Windows registry for WindowsXP at Start>Run>”regedit”>Ok>HKEY_LOCAL_MACHINE>Software>Microsoft>WindowsNT>CurrentVersion>Drivers32>vidc.dvsd. The value of vidc.dvsd is the name of the DV-AVI codec on your machine.
The bad news...Premiere is not the only video editing system that runs on Windows. Although Premiere can successfully reside on the same system as some other video editing systems, this isn’t always the case. Some video editing software, particularly those designed as simple video editing systems, will update the registry vidc.dvsd value to use other codecs specifically designed for that software. The result usually is problems within Premiere because the codec is not compatible with DV-AVI.
If black video or other similar problems are occurring, the easiest method to diagnosis the problem is click on the problem clip within Premiere then Project>Settings Viewer. Premiere will show items in red if there is a codec conflict. If a codec problem is identified, the next step is to remove the offending program. Known problems programs include: Angel Potion, Nimo, and Video Impression (DVSoft.dll) that is part of Easy CD Creator Platinum. The program creator may be identified by locating the module, named in the registry in the vidc.dvsd statement, in C:/Windows/System32, right-click on the module, choose properties, version tab, and selecting company. If you’re lucky removing the program or codec pack will also remove the problem codec. Sometimes the codec isn’t removed because removing the codec would make any video created with the codec unplayable. After removing the problem program or codec pack, you may need to manually update vidc.dvsd to switch it to the Microsoft DV-AVI module, msvidc32.dll. To modify a registry variable, click on it>edit>modify. I always write down the original value of a registry value and set a system restore point before changing the registry.
Another frequent cause of black video or poor quality video in Premiere is the use of video encoded with an output codec within video editing. Using video encoded with Windows Media, MPEG-1, MPEG-2, and AVI-DivX for editing frequently causes problems. Although Premiere 6.5 allows importing of many of these file types, the results are frequently unsatisfactory. The best solutions are to either re-capture the video using Premiere or use VirtualDub from www.DVDRHELP.com to convert the files to DV-AVI. Converting files to DV-AVI will eliminate technical problems but quality problems will likely persist. There are some circumstances, such as importing from a memory stick/card or where original video is not available, where using MPEG-1 is unavoidable. Importing MPEG-1 (.mpg) may produce satisfactory results but always results in long rendering times.
Still another cause of poor quality video is use of codecs that are not in conflict with DV-AVI but are not DV-AVI. For example, it is possible to import AVI-Cinepak files into Premiere but Premiere will uncompress the video using Cinepak and then re-compress it using DV-AVI to create preview files and for final output. Decompressing and recompressing video with different codecs may result in degradation of quality. Again, Project>Settings Viewer will help identify these problems. Sometimes these problems are unavoidable but use DV-AVI, whenever possible.
Sometimes someone will provide you with an AVI file and it does not work and you’re not sure how it was created. AVICodec at www.DVDRHELP.com can assist with identifying the codec.
All of the codecs discussed so far are video codecs. Audio codecs can have similar problems, such as stuttering audio, audio not in sync with the video, etc. The most frequent problems with audio codecs are use of Windows Media Audio, MP3, or importing audio at a different khz rating than the project settings. Audio should be in .WAV or .AVI formats. Use of Goldwave or other audio editing software is recommended to convert audio to a WAV file with the same khz as the Premiere project, usually 44 khz.
One exception is that when importing video from Adobe After Effects, it may be necessary to preserve the alpha channel from After Effects. To preserve the alpha channel, the video must be in either .MOV (RGB + Alpha) or AVI uncompressed (with “millions+”) formats. If preserving the alpha channel isn’t necessary, then your DV-AVI codec should be used in After Effects to eliminate de-compressing and re-compressing within Premiere.
Output codecs are somewhat more complicated than editing codecs (just use DV-AVI!) and will be discussed in a separate tutorial.