Encode or Convert Audio / Video

Encodes a set of images into a video, using custom container format, codec, fps, video filters, and audio track. If input contains video files, this effectively combines and converts them to the specified output format.

Usage

av_encode_video(
  input,
  output = "output.mp4",
  framerate = 24,
  vfilter = "null",
  codec = NULL,
  audio = NULL,
  verbose = TRUE
)

av_video_convert(video, output = "output.mp4", verbose = TRUE)

av_audio_convert(
  audio,
  output = "output.mp3",
  format = NULL,
  channels = NULL,
  sample_rate = NULL,
  bit_rate = NULL,
  start_time = NULL,
  total_time = NULL,
  verbose = interactive()
)

Arguments

input

a vector with image or video files. A video input file is treated as a series of images. All input files should have the same width and height.

output

name of the output file. File extension must correspond to a known container format such as mp4, mkv, mov, or flv.

framerate

video framerate in frames per seconds. This is the input fps, the output fps may be different if you specify a filter that modifies speed or interpolates frames.

vfilter

a string defining an ffmpeg filter graph. This is the same parameter as the -vf argument in the ffmpeg command line utility.

codec

name of the video codec as listed in av_encoders. The default is libx264 for most formats, which usually the best choice.

audio

audio or video input file with sound for the output video

verbose

emit some output and a progress meter counting processed images. Must be TRUE or FALSE or an integer with a valid av_log_level.

video

input video file with optionally also an audio track

format

a valid output format name from the list of av_muxers(). Default NULL infers format from the file extension.

channels

number of output channels. Default NULL will match input.

sample_rate

output sampling rate. Default NULL will match input.

bit_rate

output bitrate (quality). A common value is 192000. Default NULL will match input.

start_time

number greater than 0, seeks in the input file to position.

total_time

approximate number of seconds at which to limit the duration of the output file.

Details

The target container format and audio/video codes are automatically determined from the file extension of the output file, for example mp4, mkv, mov, or flv. For video output, most systems also support gif output, but the compression~quality for gif is really bad. The gifski package is better suited for generating animated gif files. Still using a proper video format is results in much better quality.

It is recommended to use let ffmpeg choose the suitable codec for a given container format. Most video formats default to the libx264 video codec which has excellent compression and works on all modern browsers, operating systems, and digital TVs.

To convert from/to raw PCM audio, use file extensions ".ub" or ".sb" for 8bit unsigned or signed respectively, or ".uw" or ".sw" for 16-bit, see extensions in av_muxers(). Alternatively can also convert to other raw audio PCM by setting for example format = "u16le" (i.e. unsigned 16-bit little-endian) or another option from the name column in av_muxers().

It is safe to interrupt the encoding process by pressing CTRL+C, or via setTimeLimit. When the encoding is interrupted, the output stream is properly finalized and all open files and resources are properly closed.

See also

Other av: capturing, demo(), formats, info, logging, read_audio_fft()