Videomaker – Learn video production and editing, camera reviews › Forums › General › Video and Film Discussion › AVCHD to AVI › You and I never work with
You and I never work with uncompressed video. All popular video codecs use lossy compression, including DV which compresses the video bitstream approximately 10:1 (including chroma subsampling). DV uses spatial compression on each picture, similar to creating a JPEG image (but slightly different than JPEG). DV does not use temporal compression (inter-frame compression, where some video frames are expressed in terms of the preceding or following frames). MPEG-2 and AVC (H.264) are more efficient codecs than DV, achieving a lower bitrate for a given level of quality. They use both intra-frame and inter-frame compression. DV is standard definition video only (720×480 pixel picture size in NTSC land). AVCHD, on the other hand, is normally shot in high definition (1440×1080 or 1920×1080 pixels), although it is possible to shoot standard def AVCHD (a contradiction in terms… should we call it AVCSD?).
I think the more important issue is whether you want to preserve the video in high definition while you are editing, or not. If you would like to save the final video in HD, you’ll want to edit it in AVCHD format. Generally it’s a better workflow to preserve your camcorder’s full quality through the editing process. This lets you choose from a variety of output formats when you are finished, and your video software should be able to do an optimal conversion in each case. Every time your video is rendered and re-encoded, it loses quality. Ultimately, when you create a DVD title your video software will have to render the frames and re-encode the video to MPEG-2. Ideally, this would be the one and only time your video is re-encoded.
I would recommend Cyberlink PowerDirector 7 (naturally… I work for Cyberlink). Cyberlink’s patented Smart Video Rendering Technology lets you edit AVCHD directly. For scenes that don’t include effects, transitions or overlays, PowerDirector will transfer the full, original camcorder video to your AVCHD output or Blu-ray disc. This is both faster and higher quality than the alternative – rendering and re-encoding the video. PowerDirector will also take advantage of your ATI or nVidia graphics board, using the graphics processor to speed up effects and encoding.
If your friend will edit your video on the Mac, check to see if he has an update version of iMovie, which can handle AVCHD directly. Then you can hand him your camcorder, and he can capture the video directly.