There are 3 file types use the .LDF file extension:
1. Lingoes Dictionary Source File
Source file used for specifying dictionary information for Lingoes, a dictionary and text translation program; saved in a plain text format and contains dictionary title information as well as terms and their definitions.
LDF files are compiled into .LD2 files, which can be imported into the Lingoes software. Currently, users cannot compile their own dictionaries, but Lingoes Project plans to release Lingoes Dictionary Creator software, which will allow users to create LD2 files.
Updated: October 11, 2011
2. SQL Server Transaction Log File
An LDF file is a log file created by SQL Server, a relational database management system (RDBMS) developed by Microsoft. It contains a log of recent actions executed by the database and is used to track events so that the database can recover from hardware failures or other unexpected shutdowns.
LDF files are transaction logs. These logs contain a history of activity for both fully committed and partially committed transactions to the database (the .MDF file). After an unexpected shutdown, SQL Server can use the transaction log to restore the database to the exact state before the failure.
Transaction logs can be truncated once the database creates a checkpoint, which is a stable state of the database and the log file. RDBMS systems can then safely delete all log data up to the point of the checkpoint, reducing the log file size.
NOTE: LDF files can become very large in size. This is due to the fact that no checkpoint has recently been created. However, it also may be due to open transactions that have not yet been fully committed, or other locks on database records.
Updated: October 17, 2017
3. LaserDisc FLAC-compressed File
An LDF file is an .LDS (LaserDisc Sample) file compressed using ld-compress, a tool that compresses LDS files using the Free Lossless Audio Codec (FLAC). It contains encoded analog data created by capturing the raw radio frequency produced by a LaserDisc player's laser. LDF files most likely contain data copied from a BBC Domesday LaserDisc, using Domesday86.
In 1986, the BBC finished and released the results of its Domesday project. The project, which sought to produce a picture of the United Kingdom's then-current culture, was comprised of maps, photos, statistical data, and videos. This data, gathered from over 1 million British people, was stored on LaserDics in the LaserVision Read Only Memory (LV-ROM) format. The discs' data could be viewed only on a specialized BBC Master PC that contained a specific Acorn Interactive Video Small Computer System Interface card that allowed the PC to interface with a Phillips VP415 LaserVision player.
As the technology required to view Domesday LaserDiscs fell out of fashion, people began working to preserve and transfer the discs' data to other media. Notably, Domesday enthusiasts Simon Inns and Ian Smallshire created the Domesday86 project and the Domesday Duplicator, which allowed them to store Domesday data in the LDS file format.
To make LDS files readable, developer Chad Page and others created the ld-decode suite of LDS decoding tools. One of these tools, ld-compress, can be used to compress LDS files into LDF files. Ld-decode itself can be used to transform LDF files into .TBC (Time-Base Corrected Video) files.
The ld-decode suite (Linux) includes several tools that allow users to interact with LDF files. You can use ld-ldf-reader to open and jump to a specific location in an LDF file, and you can use ld-decode to transform an LDF file into a TBC file. After transforming an LDF file into a TBC file, you can watch the video the TBC file contains in ld-analyze.
Updated: August 2, 2020