Technical specifications for moving images

Storage requirements for digital video


Simple formulas can be used to calculate approximate storage requirements for digital video:

File size = bitrate * number of minutes * .0075.
Bitrate = file size / (number of minutes * .0075)
Number of minutes = file size / (bitrate * .0075)

For example, 2 hours (120 minutes) of video compressed using a 175 mb/sec codec will require approximately 157.5 GB of storage space.

157.5 GB = 175 mb/sec * 120 minutes * .0075

Digital videocassettes


Digital "master" files and "access copies" produced by reformatting digital videocassettes through direct data transfer should be created according to the following technical specifications:

  1. Digital "master" file:

    1. MKV or MOV wrapper
    2. Native codec and native audio
    3. The original data should be captured in its entirety
    4. Maintain the original aspect ratio, recording standard, interlacing, number of audio channels and auxiliary information such as original timecode and closed captioning

  2. Digital "access copy":

    1. MPEG4 wrapper 
    2. Video encoded using the H.264 codec
    3. Bitrate of 5000 Kbps
    4. Audio encoded as uncompressed AAC, 44.1kHz, 256 Kbps
    5. Maintain the original aspect ratio, recording standard, frame rate, number of audio channels and auxiliary information such as original timecode and closed captioning

Technical specifications for digital "master" files by source media type


  • Technical specifications should always be tested and adjusted if necessary before digitizing or transferring a new batch of moving images.
  • Moving images acquired on optical disc (e.g., CD, DVD, Blu-Ray) are captured in the Digital Forensics Lab. See the Digital Forensics Lab manual for guidance on capturing data acquired on optical disc.
  • Digital master files for digital videocassettes (e.g., DV, DVCAM, DVCPRO, Digital8) should be generated through direct data transfer whenever possible.

Media type

Format

Video bit depthCodec

Audio data encoding

Audio bit depth

Audio sampling rate

Wrapper

Minimum file size for one hour of digital video

16 mm film

Film

10-bit

YUV 422 or FFV1

PCM

24-bit

48 kHz

MXF or MOV


35 mm film

Film

10-bitYUV 422 or FFV1

PCM

24-bit

48 kHz

MXF or MOV


UmaticMagnetic tape10-bitYUV 422 or FFV1PCM24-bit48 kHzMOV or MKV

Betacam

Magnetic tape

10-bitYUV 422 or FFV1

PCM

24-bit

48 kHz

MOV or MKV


Digital videocassette (DV, DVCAM, DVCPRO, DVCPRO HD (720p)

Magnetic tape

8-bitNative codec

Native audio encoding

Native audio encoding

Native audio encoding


MOV or MKV


DVCPRO HD 1080i and 1080pMagnetic tape10-bitNative codecNative audio encodingNative audio encodingNative audio encodingMOV or MKV

CD, DVD, Bluray

Optical disk



PCM

16-bit

44.1 kHz

ISO


References


Kong, David. "The Simple Formula to Calculate Video Bitrates." Frame.io Insider. Accessed January 14, 2021.