Encoding.com has industry-leading, proprietary support for a vast variety of caption standards into common distribution and broadcast standards. Support for adaptive packages, H.264 and H.265 embeds, transport stream encodings, MXF containers, and sidecar formats are all well-supported. Extraction and copying caption services is possible as well, and timecode offsets and framerate conversions can even be applied to some embeds.

<?xml version="1.0"?>
<query>
    <userid>[UserID]</userid> <!-- required-->
    <userkey>[UserKey]</userkey> <!-- required-->
    <action>[Action]</action> <!-- required-->
    <source>[SourceFile]</source> <!-- required-->
    <format>
        <output>[OutputFormat]</output> <!-- required-->
        <closed_captions>
            <source>[CCSource]</source>
            <copy>[yes|no]</copy>
            <direct_copy>[yes|no]</direct_copy>
            <extract>[srt|scc|dfxp]</extract>
            <mux_type>[cea-608|cea-708|timed-text|webvtt|burn-in|ismt|436m|dvb|mp4-ttml|mp4-webvtt]</mux_type>
            <language>[LanguageCode]</language>
            <name>[NameCode]</name>
            <time_offset>[TimeOffset]</time_offset>
            <vtt_segment_duration>[SegmentDuration]</vtt_segment_duration>
            <font_source>[FontSourceURL]</font_source>
            <font_size>[FontSize]</font_size>
            <align>[left|right|center]</align>
            <valign>[top|bottom|center]</valign>
            <margin_vertical>[VerticalMargin]</margin_vertical>
            <margin_left>[LeftMargin]</margin_left>
            <margin_right>[RightMargin]</margin_right>
            <add_source_offset>[yes|no]</add_source_offset>
            <!-- add_source_offset feature works only with mxf source -->
            <ignore_cc_absence>[yes|no]</ignore_cc_absence>
            <cea_data_field>[0|1]</cea_data_field>
            <scte20>[yes|no]</scte20>
            <characteristics>[Characteristics]</characteristics>
            <accessibility_scheme>[Scheme]</accessibility_scheme>
            <accessibility_value>[Value]</accessibility_value>
            <timescale>[Timescale]</timescale>
            <cea_track_id>[TrackID]</cea_track_id>
            <transparent_background>[yes|no]</transparent_background>
            <sub_path>[SubPath]</sub_path>
            <forced>[yes|no]</forced>
            <role>[SubtitleRole]</role>
            <get_from_manifest>[yes|no]</get_from_manifest>
            <add_to_manifest>[ManifestsList]</add_to_manifest>
            <vtt_split_segments>[yes|no]</vtt_split_segments>
            <cea_stream>[video|text|auto]</cea_stream>
            <page>[PageNumber]</page>
            <teletext_page_id>[PageID]</teletext_page_id>
            <emulate_rollup>[yes|no]</emulate_rollup>
            <strip_formatting>[yes|no]</strip_formatting>
            <webvtt_strip_cue_settings>[vertical|line|position|size|align|region],...</webvtt_strip_cue_settings>
            <source_framerate>[Frame rate value]</source_framerate>
            <framerate>[Frame rate value]</framerate>
        </closed_captions>
        <!-- Multiple closed captions params may be included in output format -->
        <closed_captions>
            <!-- closed captions params -->
        </closed_captions>
        <cc_muxer>[manzanita|edc1]</cc_muxer>
        <teletext>
            <vanc_line_1>[VANCLine1]</vanc_line_1>
            <vanc_line_2>[VANCLine2]</vanc_line_2>
            <vbi_line_1>[VBILine1]</vbi_line_1>
            <vbi_line_2>[VBILine2]</vbi_line_2>
        </teletext>
        <!-- format params -->
    </format>
</query>

{
    "query": {
        "userid": "[UserID]", // required
        "userkey": "[UserKey]", // required
        "action": "[Action]", // required
        "source": "[SourceFile]", // required
        "format": {
            "output": "[OutputFormat]", // required
            "cc_muxer": "[manzanita|edc1]",
            "closed_captions": [
                {
                    "source": "[CCSource]",
                    "copy": "[yes|no]",
                    "direct_copy": "[yes|no]",
                    "extract": "[srt|scc|dfxp]",
                    "mux_type": "[cea-608|cea-708|timed-text|webvtt|burn-in|ismt|436m|dvb|mp4-ttml|mp4-webvtt]",
                    "language": "[LanguageCode]",
                    "name": "[NameCode]",
                    "time_offset": "[TimeOffset]",
                    "vtt_segment_duration": "[SegmentDuration]",
                    "font_source": "[FontSourceURL]",
                    "font_size": "[FontSize]",
                    "align": "[left|right|center]",
                    "valign": "[top|bottom|center]",
                    "margin_vertical": "[VerticalMargin]",
                    "margin_left": "[LeftMargin]",
                    "margin_right": "[RightMargin]",
                    "add_source_offset": "[yes|no]",
                    // add_source_offset feature works only with mxf source
                    "ignore_cc_absence": "[yes|no]",
                    "cea_data_field": "[0|1]",
                    "scte20": "[yes|no]",
                    "characteristics": "[Characteristics]",
                    "accessibility_scheme": "[Scheme]",
                    "accessibility_value": "[Value]",
                    "timescale": "[Timescale]",
                    "cea_track_id": "[TrackID]",
                    "transparent_background": "[yes|no]",
                    "sub_path": "[SubPath]",
                    "forced": "[yes|no]",
                    "role": "[SubtitleRole]",
                    "get_from_manifest": "[yes|no]",
                    "add_to_manifest": "[ManifestsList]",
                    "vtt_split_segments": "[yes|no]",
                    "cea_stream": "[video|text|auto]",
                    "page": "[PageNumber]",
                    "teletext_page_id": "[PageID]",
                    "emulate_rollup": "[yes|no]",
                    "strip_formatting": "[yes|no]",
                    "webvtt_strip_cue_settings": "[vertical|line|position|size|align|region],...",
                    "source_framerate": "[Frame rate value]",
                    "framerate": "[Frame rate value]"
            },
                {
                    // closed captions params
                }
            ],
            "teletext": {
                "vanc_line_1": "[VANCLine1]",
                "vanc_line_2": "[VANCLine2]",
                "vbi_line_1": "[VBILine1]",
                "vbi_line_2": "[VBILine2]"
            }
          	// format params
        }
    }
}

Parameter	Description	Allowed Values	Default Value
Format-Level CC Params
cc_muxer	Preferred muxer for CEA-608/708 closed captions. Overrides default behavior and related user options. Ignored in workflows that require a specific muxer (e.g. HDR10, non-H.264/H.265 codecs).	manzanita — Manzanita muxer for CEA caption embedding edc1 — edc1 encoder pipeline	none
Closed Captions Params
source	Specify the URL to the closed captions file.	Valid URL to Closed Captions file in one of the following formats: SCC, SubRip, DFXP (TTML), SAMI, WebvTT, PAC, STL.	none
copy	If video has Closed Captions data stored in Timed Text or cea-608/cea-708 tracks, system will try to extract closed captions, and mux them to the output. If you want to mux Closed Captions to video in other (than in source video) format, you should specify source and mux_type.	yes, no	no
direct_copy	If video has Closed Captions data stored in cea-608/cea-708 tracks, system will directly copy closed captions to the output. Source and output must be the same frame rate.	yes, no	no
mux_type	Specify the closed captions mux type.	timed-text — Closed Captions would be muxed in video as 3GPP Timed Text track. cea-608— Closed Captions would be muxed in video as cea-608 track. cea-708 — 608 closed captions would be up-converted to 708 closed captions. And both, cea-608 and cea-708 closed captions, would be muxed in video stream. webvtt — webvtt file would be uploaded to same destination as result file (for HLS it would be segmented). Not available for advanced_mss output format. burn-in – SRT video subtitle burn-in. ismt – Closed Captions would be muxed in video as ismt track. Available only for advanced_dash and advanced_mss output formats. 436m – SMPTE 436m muxed VBI data. dvb - DVB subtitles, available only for MPEG-TS output mp4-webvtt – mux WebVTT to MP4 as wvtt track mp4-ttml – mux TTML to MP4 as stpp track	none
language	Set language of 3GPP Timed Text track. Works only for mux_type=timed-text.	ISO 639-1 2-char code, ISO 639-2 3-char code, or the full language name	none
name	When using a foreign language caption file for one’s outputs, you will also need to include a node in between the parent nodes for the labeling to be correct at the player level. If not defined in the request the label will default to English.	english, spanish, french, german, italian, dutch	none
extract	If video has Closed Captions data stored in Timed Text or cea-608/cea-708 tracks, system will try to extract closed captions, and upload them to same destination as the output. If video has multiple text tracks extracted files will have a numeric suffix.	srt — Closed Captions would be extracted in SubRip format scc — Closed Captions would be extracted in Scenarist Closed Captions format dfxp — Closed Captions would be extracted in DFXP format	none
time_offset	Specify the time offset for time in CC file.	Positive or negative float number	0
vtt_segment_duration	Sets segments duration for WebVTT Closed Captions.	Positive float number	none
font_source	Specify the Closed Captions font source file. Allowed font formats: ttf, otf.	Valid URL. Required for dvb mux_type.	none
font_size	Specify the closed caption font size.	Positive integer greater than 10.	16
align	Horizontal captions alignment	left, right, center	center
valign	Vertival captions alignment	top, bottom,center	bottom
margin_vertical	Vertical margin	Positive integer number	none
margin_left	Left margin	Positive integer number	none
margin_right	Right margin	Positive integer number	none
add_source_offset	Enable use of initial closed captions timestamp from source file in output initial timestamp.	yes, no	no
ignore_cc_absence	Ignore closed captions absence in a source file while copy or direct_copy closed captions.	yes, no	yes
cea_data_field	CEA-608 data field id (data type) to be extracted from cea-608 CC data.	0 – NTSC_CC_FIELD_1 _1_ – NTSC_CC_FIELD_2	0
scte20	Mux CEA closed captions with SCTE-20 stadnard.	yes, no	no
characteristics	CHARACTERISTICS attribute value for the EXT-X-MEDIA tag in HLS manifest according to RFC 8216	Valid CHARACTERISTICS value For example: public.accessibility.transcribes-spoken-dialog public.accessibility.describes-music-and-sound	none
accessibility_scheme	"schemeIdUri" attribute value for the Accessibility tag in DASH manifest	Valid SCHEME value	none
accessibility_value	"value" attribute value for the Accessibility tag in DASH manifest	Valid string	none
timescale	Timescale Value	Positive integer number	none
cea_track_id	Track ID in MOV container with CEA CC data to copy/extract. First available track with CEA CC data is used by default.	Integer number	none
transparent_background	Add transparent background for DFXP Closed Captions	yes, no	no
sub_path	ISMT and WebVTT Closed Captions files sub directory relative to the output destination	String	none
forced	Add FORCED=YES attribute to subtitle in HLS manifest	yes, no	no
role	Set subtitle's Role attribute in DASH manifest	caption, subtitle, commentary, dub, description, metadata, forced-subtitle, easyreader, karaoke	subtitle
get_from_manifest	Use data from external manifest	yes, no	no
add_to_manifest	Add closed captions data to specified manifests. By default closed caption will be added to all manifests.	Comma separated list of manifest names	none
vtt_split_segments	Split WebVtt subtitles to segments for MPEG-DASH manifest	yes, no	no
cea_stream	Stream type for closed captions extraction	video, text, auto	auto
page	Set ttxt page value	Positive integer number	none
teletext_page_id	Teletext page id to copy or extract	Non-negative integer number	none
emulate_rollup	Perform RollUp emulation when converting an SCC file to other formats	yes, no	yes
strip_formatting	Remove all formatting tags (available only for TTML (DFXP) output and TTML to WebVTT conversion).	yes, no	no
webvtt_strip_cue_settings	Strip certain cue settings	Comma separated list of the following values: vertical,line,position,size,align,region	none
Teletext Parameters
vanc_line_1	VANC Line 1 value for teletext ancillary data	Positive integer number	12
vanc_line_2	VANC Line 2 value for teletext ancillary data	Positive integer number	575
vbi_line_1	VBI Line 1 value for teletext ancillary data	Positive integer number	21
vbi_line_2	VBI Line 2 value for teletext ancillary data	Positive integer number	334

🚧
For mux_type parameter
cea-608 mux type works with libx264 and hevc video codec.
cea-708 mux type works only with libx264 video codec.

🚧
For font_source and font_size parameters
<font_source /> and <font_size /> work only with burn-in mux type.

🚧
For scte20 parameter
parameter available only for mpeg2video video codec.

🚧
For characteristics parameter
parameter available only for advanced_hls, fmp4_hls, and HLS manifests of advanced_fmp4 output formats.

🚧
For accessibility_scheme, accessibility_value, and timescale parameters
<accessibility_scheme />, <accessibility_value />, and parameters available only for advanced_dash and DASH manifests of advanced_fmp4 output formats.

🚧
For timescale parameter
The parameter applied only if <mux_type /> set to ismt.

🚧
For transparent_background parameter
The <transparent_background /> parameter applied only if set to dfxp and <mux_type /> not set.

🚧
For sub_path parameter

The <sub_path /> parameter available only for advanced multi-bitrate output formats.

The <sub_path /> parameter applied only if <mux_type /> set to ismt or webvtt.

🚧
For forced parameter

The parameter available only for advanced_hls, fmp4_hls, and HLS manifests of advanced_fmp4 output formats.

🚧
For role parameter

The parameter available only for advanced_dash and DASH manifests of advanced_fmp4 output formats.

🚧
For get_from_manifest parameter

The <get_from_manifest /> parameter available only for advanced_hls, fmp4_hls, advanced_dash, and advanced_fmp4 output formats.

The <get_from_manifest /> parameter available only if manifest are specified.

🚧
For add_to_manifest parameter
The <add_to_manifest /> parameter available only for advanced_hls, fmp4_hls, advanced_dash, and advanced_fmp4 output formats.

🚧
For vtt_split_segments parameter
The <vtt_split_segments /> parameter available only for advanced_dash and DASH manifests of advanced_fmp4 output formats.

🚧
For mux_type and teletext params
The mux_type value 436m and teletext parameters available only for mxf_op1a output format
🚧 For multiple cea-608/708 <closed_captions> blocks
If there are two cea-608/708 <closed_captions> blocks, cea-608 captions will be placed to CC1 and CC3 channels, in case of more than two blocks, they will be placed to the channels with sequential indices, i.e. CC1, CC2, CC3, CC4. cea-708 captions are always placed to channels with sequential numbers (Service1, Service2, etc.)