Class: shaka.cea.Mp4CeaParser

Constructor

new Mp4CeaParser()

Implements:
Source:

Members

BitstreamFormat :number

Type:
  • number
Properties:
Name Value Type Description
UNKNOWN 0 number
H264 1 number
H265 2 number
H266 3 number
C608_TRACK 4 number
AV1 5 number
Source:

CodecBitstreamMap_ :Map<string, shaka.cea.Mp4CeaParser.BitstreamFormat>

Type:
Source:

METADATA_TYPE_ITUT_T35_ :number

METADATA_TYPE_ITUT_T35, as defined by the AV1 bitstream specification.
Type:
  • number
Source:

OBU_TYPE_METADATA_ :number

OBU_METADATA, as defined by the AV1 bitstream specification.
Type:
  • number
Source:

bitstreamFormat_ :shaka.cea.Mp4CeaParser.BitstreamFormat

Type:
Source:

c608TrackId_ :number

Type:
  • number
Source:

defaultSampleDuration_ :number

Default sample duration, as specified by the TREX box.
Type:
  • number
Source:

defaultSampleSize_ :number

Default sample size, as specified by the TREX box.
Type:
  • number
Source:

seiProcessor_ :shaka.cea.SeiProcessor

SEI data processor.
Type:
Source:

trackIdToTimescale_ :Map<number, number>

Map of track id to corresponding timescale.
Type:
  • Map<number, number>
Source:

Methods

readLeb128_(datanon-null, offset) → {?{value: number, size: number}}

Reads the AV1 leb128() at the given offset. Returns null if the value is truncated or malformed, in which case the rest of the sample cannot be trusted either.
Parameters:
Name Type Description
data Uint8Array
offset number
Source:
Returns:
Type
?{value: number, size: number}

init(initSegmentnon-null)

Parses the init segment. Gets Default Sample Duration and Size from the TREX box, and constructs a map of Track IDs to timescales. Each TRAK box contains a track header (TKHD) containing track ID, and a media header box (MDHD) containing the timescale for the track
Parameters:
Name Type Description
initSegment BufferSource init segment to parse.
Implements:
Source:

parse(mediaSegmentnon-null) → {Array<!shaka.extern.ICeaParser.CaptionPacket>}

Parses each video segment. In fragmented MP4s, MOOF and MDAT come in pairs. The following logic gets the necessary info from MOOFs to parse MDATs (base media decode time, sample sizes/offsets/durations, etc), and then parses the MDAT boxes for CEA-708 packets using this information. CEA-708 packets are returned in the callback.
Parameters:
Name Type Description
mediaSegment BufferSource media segment to parse.
Implements:
Source:
Returns:
Type
Array<!shaka.extern.ICeaParser.CaptionPacket>

parseAv1Sample_(samplenon-null, pts, captionPacketsnon-null)

Parses the OBUs of a single AV1 coded sample (one temporal unit) and extracts the caption payload of every metadata_itu_t_t35 OBU. AV1 has no NAL units, so the cc_data() that AVC/HEVC carry in an SEI message rides in a metadata OBU placed before the frame OBU instead. The T.35/GA94 header and the cc_data() below it are identical to the SEI case, so only the envelope differs and the extracted payload is handed to the decoder as an SEI packet. OBUs carry no emulation prevention bytes, which is why the payload does not go through the SEI processor.
Parameters:
Name Type Description
sample Uint8Array
pts number
captionPackets Array<!shaka.extern.ICeaParser.CaptionPacket>
Source:

parseC608Mdat_(readernon-null, time, timescale, defaultSampleDuration, defaultSampleSize, offset, parsedTRUNsnon-null, captionPacketsnon-null)

Parse MDAT box for C608 format
Parameters:
Name Type Description
reader shaka.util.DataViewReader
time number
timescale number
defaultSampleDuration number
defaultSampleSize number
offset number
parsedTRUNs Array<shaka.util.ParsedTRUNBox>
captionPackets Array<!shaka.extern.ICeaParser.CaptionPacket>
Source:

parseMdat_(readernon-null, time, timescale, defaultSampleDuration, defaultSampleSize, offset, parsedTRUNsnon-null, captionPacketsnon-null)

Parse MDAT box.
Parameters:
Name Type Description
reader shaka.util.DataViewReader
time number
timescale number
defaultSampleDuration number
defaultSampleSize number
offset number
parsedTRUNs Array<shaka.util.ParsedTRUNBox>
captionPackets Array<!shaka.extern.ICeaParser.CaptionPacket>
Source:

setBitstreamFormat_(codec)

Parameters:
Name Type Description
codec string A fourcc for a codec.
Source:

Type Definitions

ParsedTRAF

Type:
  • {trackId: ?number, baseMediaDecodeTime: ?number, defaultSampleDuration: number, defaultSampleSize: number, parsedTRUNs: !Array<shaka.util.ParsedTRUNBox>, timescale: number}
Properties:
Name Type Attributes Description
trackId number <nullable>
baseMediaDecodeTime number <nullable>
defaultSampleDuration number
defaultSampleSize number
parsedTRUNs Array<shaka.util.ParsedTRUNBox>
timescale number <nullable>
Source: