Editing HDV

Editing High-definition video: The HDV uses the interframe MPEG-2 GOP (group of pictures) structure instead of a solely intraframe compression system, native editing of HDV footage differs technically from the native editing of DV footage. In DV, frame-accurate splicing does not disturb the surrounding video because each frame of the video is stored as a self-contained unit. In HDV, splicing always introduces distortion at the splice points, due to the interdependencies between groups of video frames.

Any editing of the video, whether it be a complex transition or a simple scene-change, requires a decompression and recompression of the entire HDV frame group. All modern professional non-linear editing software handles HDV by recompressing only in scenes where absolutely necessary, rather than needlessly recompressing the entire video. This limits degradation to the points of edit.
Editing HDV's native MPEG-2 transport stream files also forces the computer system to work much harder to perform even simple tasks of cutting and splicing as frames that do not actually exist as independent cells have to be re-built by the NLE system on-the-fly.
If HDV footage is converted (or Transcoding) to a good intermediate format for editing, these considerations will not necessarily apply, and gradual degradation from generation to generation of edit may be avoided while substantial system performance gains are made. The lossy Apple Intermediate Codec (which runs out of QuickTime) is an efficient, easily usable codec for editing HDV in systems such as Final Cut Pro but lacks the transcoding and generational quality of some third-party HDV Intermediate codecs. CineForm's ConnectHD, AspectHD and ProspectHD intermediate codecs and encoding utilities not only maintain higher quality but also function within the rendering engine of some software editing systems (such as Premiere Pro) to boost real-time performance without hardware assistance. CineForm products currently work with Sony Vegas, Premiere Pro, and Corel's Ulead MediaStudio Pro 8 and Ulead Videostudio 11 Plus editing systems. Lumiere HD offers a similar functionality for Mac based editing systems (namely Final Cut Pro) but without any real-time assistance. BitJazz's SheerVideo offers lossless real-time codecs that speed editing with zero generational loss, although Final Cut Pro only supports camera manufacturer third-party codecs for real-time effects.
There are many advantages to editing HDV using a Lossless Intermediate rather than the native MPEG-2 file however the trade off for transcoding to a HDV Lossless Intermediate is that the file size is substantially increased and so large hard drive arrays are required for storage of footage. Avid Xpress Pro can edit using native HDV, and Avid also claims to have the advantage of being able to work with mixed formats in the timeline, without the need to transcode any material, since different formats are coped with seamlessly for viewing and output, with automatic conversion as required.

Apple's Final Cut Studio also handles native HDV with realtime effects without any additional hardware and will mix it with other frame sizes as well as frame rates in the same sequence. It must be noted though that when DV material, for example, is included in an HDV project, a problem arises because it must be de-interlaced prior to scaling to the HDV format, and then re-interlaced. De-interlacing is generally regarded as a very difficult process to do well. This problem will arise of course in all editing software, regardless of whether a lossless intermediate format is used.