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

2304 kbps (mono) or 4608 kbps (stereo)

Preservation master -
digital source
Broadcast WAV  At original resolution
(typically 16-bit) 
At original resolution
(typically 44.1 or 48 kHz)
1411.2 kbps or 1536 kbps
Production-quality access file Broadcast WAV 16-bit 44.1 kHz

705.6 kbps (mono) or 1411.2 kbps (stereo)

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
Uncompressed YUV / QuickTime 8-bit
or 10-bit
4:2:2

720x486 (NTSC) or 720x576 (PAL)

same as source ~20.3 MB/sec or ~27 MB/sec PCM; 48 kHz;
16-bit or 24-bit
Preservation master -
digital source
DV-format variants / QuickTime 8-bit 4:1:1 720x480 (DV-NTSC) or 720x576 (PAL)
1440x1080 (HDV)
same as source  ~25 Mbps PCM; as low as 12-bit/32 kHz and as high as 20-bit/48 kHz
Streaming file H264/MP4 8-bit  4:2:0  640x480 (SD) or 1280x720 (HD) same as source  1100 kbps (SD) or 2800 kbps (HD) AAC; stereo; 128 or 192 kbps; 48 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 as of late 2017. 

File type Wrapper Bit depth Color Model Frame size Audio
Preservation master -
8mm source
dpx 10, 12, or 16-bit RGB Log or Linear

2048x1556 or 3840x2160

PCM, 24-bit/48 kHz
or 24-bit/96 kHz

Preservation master -
16mm or 35mm source
dpx 10 or 16-bit RGB Log or Linear

2048x1556 or 4096x3112

PCM, 24-bit/48 kHz
or 24-bit/96 kHz

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