Stream descriptors

There can be multiple stream_descriptor with input from the same “file” or multiple different “files”.

Stream descriptor is of the form:

<field>=<value>[,<field>=<value>]...

These are the available fields:

input (in)

input/source media “file” path, which can be regular files, pipes, udp streams. See UDP file options on additional options for UDP files.

stream_selector (stream)

Required field with value ‘audio’, ‘video’, ‘text’ or stream number (zero based).

output (out)

Required output file path (single file).

init_segment

initialization segment path (multiple file).

segment_template (segment)

Optional value which specifies the naming pattern for the segment files, and that the stream should be split into multiple files. Its presence should be consistent across streams. See Segment template formatting.

bandwidth (bw)

Optional value which contains a user-specified maximum bit rate for the stream, in bits/sec. If specified, this value is propagated to (HLS) EXT-X-STREAM-INF:BANDWIDTH or (DASH) Representation@bandwidth and the $Bandwidth$ template parameter for segment names. If not specified, the bandwidth value is estimated from content bitrate. Note that it only affects the generated manifests/playlists; it has no effect on the media content itself.

language (lang)

Optional value which contains a user-specified language tag. If specified, this value overrides any language metadata in the input stream.

output_format (format)

Optional value which specifies the format of the output files (MP4 or WebM). If not specified, it will be derived from the file extension of the output file.

For subtitles in MP4, you can specify ‘vtt+mp4’ or ‘ttml+mp4’ to control which text format is used.

trick_play_factor (tpf)

Optional value which specifies the trick play, a.k.a. trick mode, stream sampling rate among key frames. If specified, the output is a trick play stream.

cc_index

Optional value which specifies the index/ID of the subtitle stream to use for formats where multiple exist within the same stream. For example, CEA allows specifying up to 4 streams within a single video stream. If not specified, all subtitles will be merged together.

DRM related Stream descriptor fields

skip_encryption=0|1

Optional. Defaults to 0 if not specified. If it is set to 1, no encryption of the stream will be made.

drm_label

Optional value for custom DRM label, which defines the encryption key applied to the stream. Typically values include AUDIO, SD, HD, UHD1, UHD2. For raw key, it should be a label defined in –keys. If not provided, the DRM label is derived from stream type (video, audio), resolutions, etc. Note that it is case sensitive.

DASH specific stream descriptor fields

dash_accessibilities (accessibilities)

Optional semicolon separated list of values for DASH Accessibility element. The value should be in the format: scheme_id_uri=value, which propagates to the Accessibility element in the result DASH manifest. See DASH (ISO/IEC 23009-1) specification for details.

dash_roles (roles)

Optional semicolon separated list of values for DASH Role element. The value should be one of: caption, subtitle, main, alternate, supplementary, commentary and dub. See DASH (ISO/IEC 23009-1) specification for details.

HLS specific stream descriptor fields

hls_name

Used for HLS audio to set the NAME attribute for EXT-X-MEDIA. Defaults to the base of the playlist name.

hls_group_id

Used for HLS audio to set the GROUP-ID attribute for EXT-X-MEDIA. Defaults to ‘audio’ if not specified.

playlist_name

The HLS playlist file to create. Usually ends with ‘.m3u8’, and is relative to hls_master_playlist_output (see below). If unspecified, defaults to something of the form ‘stream_0.m3u8’, ‘stream_1.m3u8’, ‘stream_2.m3u8’, etc.

iframe_playlist_name

The optional HLS I-Frames only playlist file to create. Usually ends with ‘.m3u8’, and is relative to hls_master_playlist_output (see below). Should only be set for video streams. If unspecified, no I-Frames only playlist is created.

hls_characteristics (charcs)

Optional colon or semi-colon separated list of values for the CHARACTERISTICS attribute for EXT-X-MEDIA. See CHARACTERISTICS attribute in http://bit.ly/2OOUkdB for details.