Capture specs

The Stanford Media Preservation Lab produces audio and moving image files suited to purpose. This page outlines the encoding specifications we follow.

Audio

A preservation master file is created to serve as the highest-quality archival master to be maintained in perpetuity for creating reproductions of the original recording. For digital sources, like DAT, the goal is to match the original resolution and encoding specs as closely as possible, if not exactly, in the master file. The production-quality access file is a high-quality version of the archival master useful for transcoding to a variety of user-friendly formats and media, such as Audio CD. The online access file is optimized for delivery via streaming or download. Other options, depending on the end-use context or delivery system, are possible.

File type Format Bit depth Sampling rate Bitrate
Preservation master -
analog source
Broadcast WAV 24-bit 96 kHz N/A
Preservation master -
digital source
Broadcast WAV  At original resolution
(typically 16-bit) 
At original resolution
(typically 44.1 or 48 kHz)
N/A
Production-quality access file Broadcast WAV 16-bit 44.1 kHz N/A
Online access file M4A  N/A 44.1 kHz 128 kbps (mono) or
256 kbps (stereo)

Video

A preservation master file is created to serve as the highest-quality archival master to be maintained in perpetuity for creating reproductions of the original recording. For digital sources, like DV, the goal is to match the original resolution and encoding specs as closely as possible, if not exactly, in the master file. The production-quality access file is a high-quality version of the master and is useful as a transcoding master or for access in cases where detailed or close review is necessary. Online access files are available to researchers in reading rooms and listening rooms at Stanford.

Typical outputs are listed below. Other options, depending on the end-use context or delivery system, are available.

File type Format/wrapper Bit depth Color sub-sampling Frame size Frame rate Video bitrate Audio
Preservation master -
analog source
QuickTime Uncompressed 8-bit
or 10-bit
4:2:2 720x486 29.97 fps 27 MB/sec fixed PCM; 48 kHz;
16-bit or 24-bit
Preservation master -
digital source
QuickTime 8-bit 4:1:1 720x480
1440x1080 (HDV)
29.97 fps  25 Mbps PCM; as high as 48 kHz
and 20-bit
High quality access file MPEG-2 8-bit 4:2:0 720x480 29.97 fps 8 Mbps variable MPEG-1 Layer 2;
384 kbps; 48 kHz
Online access file QuickTime
H.264/AVC
8-bit  4:2:0  640x480 same as source  800 kbps - 1700 kbps

AAC; stereo;
192 kbps; 44.1 kHz 
Streaming file H.264 8-bit  4:2:0  variable same as source  ~600 kbps  MP3; stereo;
128 kbps; 44.1 kHz 

Film

Stanford's approach to film reformatting is evolving. While we have done some film-to-film transfers in the past, digital capture of film originals as video is now preferable given available resources and user requirements. We can more effectively manage reformatted film content with our current digital repository infrastructure than preserve new physical film elements in collection storage facilities.

The table below outlines film reformatting specifications followed to date. We continually monitor the latest developments in film scanning technology, and anticipate pursuing 2K and 4K capture when circumstances allow. 

File type Wrapper Bit depth Color sub-sampling Frame size Frame rate Video bitrate Audio
Preservation master -
8mm source
QuickTime 10-bit 4:2:2

1280x720 or 
1920x1080

16 or 18 fps playback
with pulldown added for 23.98 fps (variable)

133 MB/sec maximum
(frame size and fps dependent)

PCM, 48 kHz
and 24-bit

Preservation master -
16mm or 35mm source
QuickTime 10-bit 4:2:2

1920x1080i

23.98 fps

133 MB/sec fixed

PCM, 48 kHz
and 24-bit