Avid and HDHigh Definition comes in various flavours, with HDV being just one. HDV Avid Media Composer supports 1080i HDV as well as Panasonic DVCProHD and JVC 720p @30fps and finally in version 3 JVC @25fps. It supports editing the footage natively - which means it uses HDV as it came in from the camera and does not convert it to a less compressed format. You can do this after capture if you prefer but Avid does work very well with native files. Sony XDCAMHD Media supports XDCam HD at all settings. It supports using XDCam-EX via the Sony clip browser software, Using the latter you convert the XDCam-EX native MP4 files into MXF (this involves converting the file header not the footage so is quick) and then import these into Avid. Panasonic DVCPro HD/P2 Media Compose supports P2 and DVC Pro HD extensively. Editing HD footage in Xpress Pro and Media Composer When you start a project in Avid you choose a preset which defines the editing mode. However, once in Avid this can be varied between standard definition, HDV and full High Definition. Which mode you are in will then determine at what quality your effects are rendered, with which codec, and where you will see the picture. At standard definition everything plays out through the Mojo, or to a DV device attached to the PC. At HD or HDV resolutions the playback is on screen only - if running two screens you can play the edit full screen on one monitor via the second output of your graphic card. This is not quite as good as output from a proper a device like a Matrox RT.X2, but it is much better than just an overlay.
You can have an HD project and edit it at standard definition with full output through the Mojo so you can judge colour correction etc. and then at the end of the edit switch it to HD for the final render. Lots of Codecs Media Composer does have a wide variety of codecs. For standard definition there is DV and an even lower size format called 15:1s. With the latter you can capture a hour of footage and it only takes up around 1.5GB space. You edit off-line in this format and then re-capture just the sections used later at full quality. For High Definition there are also several formats. Firstly Avid supports HDV editing in native MPEG. This is actually very well implemented and MPEG footage is very nice to use. Next there are several variations of what Avid call the DNxHD codec. This is a compressed format, invented by Avid to solve the problem of editing HD footage without choosing to use uncompressed formats which take huge amounts of space. These are practically impossible to use across a network to share with other users - something that is an essential part of Avid’s use in broadcast. Like the Canopus and CineForm formats, Avid DNxHD saves each frame as a single frame, so it is nicer to use than MPEG and can do more in realtime. It is really intended for use with formats higher than HDV - if the project is in HDV mode then you cannot convert it to DNxHD and you have to switch to full HD mode to do this. However, once you have switched you just select several clips and choose transcode and leave Xpress Pro to get in with it. Once complete you get superior performance and more realtime effects, at the cost of more hard drive space used. Realtime performance is not as good as Canopus Edius, and comparable with Adobe Premiere Pro or Avid Liquid. If you choose to stay in the native mode, which most users will as it is actually pretty good, DNxHD still has a benefit. All effects are rendered to DNxHD, not MPEG format as with Avid Liquid, or Apple’s Final Cut Pro. This is quicker and also means that you do not risk problems rendering many generations of effects. Suppose you add an effect, render it, then add another, re-render and so on. If rendering into MPEG then each re-render adds possible artifacts because it is being saved in a highly compressed form (just like remaking footage from a DVD several times). By using the DNxHD codec Avid avoids this, and so is better for quality. | 
