Video with Linux

Aquisition and Distribution Formats

An aquisition format is used to record the video; a distribution format is used to play it. If the recording format of a camcorder is also a distribution format then no format conversion is necessary to watch the video without the camcorder. This is often marketed as a convenience. However, if you have to decompress and recompress the video anyway when editing it doesn't make any difference whether the aquisition format is the same as the distribution format. Consumer camcorder recording formats are summarized in the table 
    format        year        aquisition        distribution
     Beta         1982         yes               yes
     VHSC         1982         yes               almost [1]
     VHS          1985         yes               yes
     8mm          1984         yes               no
     Hi8          1989         yes               no
     miniDV       1998         yes               no
     Digital 8    1999         yes               no
     DVD          2000         yes               yes
     HDV          2003         yes               almost [2]
     AVCHD        2006         yes               yes [3]
Notes:
  1. Though VHSC cassettes are not a distribution media, they can be played in a VHS player by means of a simple adaptor. Moreover, the 1/2 inch tape from a VHSC cassette can be placed into a standard size cassette and played with no format conversion.

  2. Though HDV tape is not a distribution media, the data stored on the tape can be downloaded to a computer and directly burned to Blu-ray disk with no format conversion.

  3. Some AVCHD camcorders record to Blu-ray or DVD. Others record to internal memory that can be downloaded and burned to DVD or Blu-ray disk with no format conversion.
Professional and prosumer videographers will archive the original media and make edited copies for distribution. These users want to create a final product with consistent color and sound. Software exists to losslessly correct brightness and color in jpeg images and the volume in mp3 encoded sound files. However, there is no software available that can to do the same with mpeg2 video, h264 video, ac3 audio or aac audio. Therefore, a decompress and recompress cycle will have to be performed because of the editing regardless of whether the aquisition format is the same as the distribution format. For more information see Editing AVCHD with Cinelerra.

A consumer will watch the original media and then give it to a friend to watch. Editing involves cut and paste from the original source. Since software exists to perform cut and paste editing of mpeg2 and avchd without reencoding, quality and time can be saved if the aquisition format is the same as the distribution format. For more information see Lossless ACHD Editing in Linux.

Further Notes

MiniDV is easy to edit because it was was adapted from an aquisition format designed for professional use. DVD, HDV and AVCHD were adapted from delivery formats for use as aquisition formats. These formats are more complicated to edit.

When the aquisition format is the same as the delivery format the video quality of the original source can be fully preserved with a lossless cut and paste editing workflow. It would be a wonderful addition to the lossless workflow if color correction and volume adjustments could also be made. A Linear Color Correction Method for Compressed Images and Videos by Kebin An, Jun Sun and Lei Zhou suggests this should be possible. In this case, a video project authored with a lossless workflow could also enjoy consistent color and sound.

Page written and maintained by Eric Olson
Last Updated: Sun Aug 16 15:50:54 PDT 2009