RTMP.Frame (rtmp v0.1.0)

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One audio or video frame, as delivered to RTMP.Handler.handle_frame/2.

Fields

  • :type — :audio or :video.
  • :codec — :aac or :h264 (parsed), or the FLV codec of a frame passed through unparsed (:mp3, :speex, :vp6, ...), or {:unknown, id}.
  • :dts — decode timestamp in milliseconds: the RTMP message timestamp. 32-bit, wraps after about 49.7 days.
  • :cts — composition time offset in milliseconds (video only; 0 for audio). The presentation timestamp is dts + cts — see pts/1.
  • :keyframe? — video keyframe. Always false for audio.
  • :sequence_header? — this frame is decoder configuration, not media: an AAC AudioSpecificConfig or an H.264 AVCDecoderConfigurationRecord. Encoders send one before the first media frame and again if the configuration changes.
  • :parsed? — whether the codec payload was parsed. false for codecs that are passed through as-is.
  • :data — the codec payload with the FLV tag header stripped:
    • AAC sequence header: the AudioSpecificConfig bytes.
    • AAC frame: one raw AAC frame (no ADTS header).
    • H.264 sequence header: the AVCDecoderConfigurationRecord bytes.
    • H.264 frame: length-prefixed (AVCC) NAL units.
    • Unparsed codecs: everything after the first FLV tag byte.
  • :config — for sequence headers, the parsed configuration (see RTMP.FLV.AudioTag and RTMP.FLV.VideoTag). For unparsed audio, the FLV header's rate/size/channel fields. Otherwise nil.
  • :nalus — H.264 frames only: the NAL units split out of :data, without their length prefixes. nil otherwise.
  • :stream_id — the RTMP message stream id the frame arrived on.
  • :payload — the complete RTMP message payload, which is exactly an FLV tag body. Write this verbatim when remuxing to FLV.

Binary fields are sub-binaries of the received message, so carrying both :payload and :data (and :nalus) costs no extra copies.

Summary

Types

codec()
t()

Functions

pts(frame)

Presentation timestamp in milliseconds: dts + cts.

Types

codec()

@type codec() ::
  :aac
  | :h264
  | :pcm
  | :pcm_le
  | :adpcm
  | :mp3
  | :mp3_8khz
  | :nellymoser
  | :nellymoser_8khz
  | :nellymoser_16khz
  | :g711_alaw
  | :g711_mulaw
  | :speex
  | :device_specific
  | :jpeg
  | :sorenson_h263
  | :screen_video
  | :screen_video_v2
  | :vp6
  | :vp6_alpha
  | {:unknown, non_neg_integer()}

t()

@type t() :: %RTMP.Frame{
  codec: codec(),
  config: map() | nil,
  cts: integer(),
  data: binary(),
  dts: non_neg_integer(),
  keyframe?: boolean(),
  nalus: [binary()] | nil,
  parsed?: boolean(),
  payload: binary(),
  sequence_header?: boolean(),
  stream_id: non_neg_integer(),
  type: :audio | :video
}

Functions

pts(frame)

@spec pts(t()) :: integer()

Presentation timestamp in milliseconds: dts + cts.