Forget what tidymedia remembers about your FFmpeg build

Discard the package's record of which encoders your FFmpeg build has. The next query then asks FFmpeg again.

Usage

refresh_ffmpeg_capabilities()

Value

NULL, invisibly. Called for its side effect.

Details

The first call in an R session that uses hardware = "nvenc" or hardware = "videotoolbox" asks FFmpeg which encoders it has. The package remembers that answer for the rest of the session. Later calls reuse it and do not start FFmpeg again each time, so a large batch stays fast.

So the package does not see a change to your FFmpeg build until you discard the record. Examples of a change are a new FFmpeg install, a new graphics card (GPU) driver, or a different FFmpeg program. There are three ways to discard the record:

• Call refresh_ffmpeg_capabilities() yourself, at any time.

• Call set_program (or set_ffmpeg). It discards the record for you, because the record describes the old program.

• Call unset_program and have it remove something. When it forgets a saved location, the package can find a different program. A call that removed nothing keeps the record, because the program in use did not change. A call that removed one saved file and then failed on another discards the record. The file it removed may have named the program that the record came from.

The glossary in vignette("tidymedia") explains media terms such as encoder and hardware encoder.

Parallel workers

Each R process keeps its own record, and a worker does not get the record of your session. So in a batch on W workers, each worker asks FFmpeg once. Your session can also ask once, before the jobs start. Discarding the record in your session does not reach the workers.

The tidymedia.hardware_encoders option works in a different way. The package copies your value into each worker for the duration of the call, and then puts back the worker's own value. So a batch under your setting does not ask FFmpeg for an encoder list at all. Every worker gives the same answer as your session.

Functions that never use the record

ffmpeg_encoders and ffmpeg_codecs ask FFmpeg on every call. So they always show the build as it is now, whether or not you called this function.

See also

has_hardware_encoder uses the remembered answer. hardware_encoder gives the encoder name without asking FFmpeg. ffmpeg_encoders always gives a fresh encoder list. set_program points the package at a different FFmpeg program.

Other capability functions: ffmpeg_codecs(), ffmpeg_encoders(), hardware_encoder()

Examples

# After installing FFmpeg, or a GPU driver or OS update mid-session:
refresh_ffmpeg_capabilities()