The field of language documentation in the modern context involves a complex and ever-evolving set of tools and methods, and the study and development of their use - and, especially, identification and promotion of best practices - can be considered a sub-field of language documentation proper. Among these are ethical and recording principles, workflows and methods, hardware tools, and software tools.
Principles and workflows
Researchers in language documentation often conduct linguistic fieldwork to gather the data on which their work is based, recording audiovisual files that document language use in traditional contexts. Because the environments in which linguistic fieldwork often takes place may be logistically challenging, not every type of recording tool is necessary or ideal, and compromises must often be struck between quality, cost and usability. It is also important to envision one's complete workflow and intended outcomes; for example, if video files are made, some amount of processing may be required to expose the audio component to processing in various ways by different software packages.
Ethics
Ethical practices in language documentation have been the focus of much recent discussion and debate. The Linguistic Society of America has prepared an Ethics Statement, and maintains an Ethics Discussion Blog which is primarily focused on ethics in the language documentation context. The morality of ethics protocols has itself been brought into question by George van Driem. Most postgraduate programs that involve some form of language documentation and description require researchers to submit their proposed protocols to an internal Institutional Review Board which ensures that research is being conducted ethically. Minimally, participants should be informed of the process and the intended use of the recordings, and give recorded audible or written permission for the audiovisual materials to be used for linguistic investigation by the researcher(s). Many participants will want to be named as consultants, but others will not - this will determine whether the data needs to be anonymized or restricted from public access.
Data Formats
Adhering to standards for formats is critical for interoperability between software tools. Many individual archives or data repositories have their own standards and requirements for data deposited on their servers - knowledge of these requirements ought to inform the data collection strategy and tools used, and should be part of a data management plan developed before the start of research. Some example guidelines from well-used repositories are given below:
Endangered Languages Archive (ELAR) guidelines
Max Planck Institute Archive accepted formats
Yale University Library audiovisual guidelines
Most current archive standards for video use MPEG-4 (H264) as an encoding or storage format, which includes an AAC audio stream (generally of up to 320 kbit/s). Audio archive quality is at least WAV 44.1 kHz, 16-bit.
Principles for recording
Since documentation of languages is often difficult, with many languages that linguists work with being endangered (they may not be spoken in the near future), it is recommended to record at the highest quality possible given the limitations of a recorder. For video, this means recording at HD resolution (1080p or 720p) or higher when possible, while for audio this means recording minimally in uncompressed PCM 44,100 samples per second, 16-bit resolution. Arguably, however, good recording techniques (isolation, microphone selection and usage, using a tripod to minimize blur) is more important than resolution. A microphone that gives a clear recording of a speaker telling a folktale (high signal/noise ratio) in MP3 format (perhaps via a phone) is better than an extremely noisy recording in WAV format where all that can be heard are cars going by. To ensure that good recordings can be obtained, linguists should practice with their recording devices as much as possible and compare the results to observe which techniques yield the best results.