frame.bend source

frame.bend on the hub · documented module

# What a session gives a program: frames, and what they are frames of.import Base# Video: one picture's access unit, its NAL units in Annex B form (each# after 00 00 00 01); key says a decoder can start at it. Audio: what# the description's audio says it is: AAC frames, each after its ADTS# header, or G.711 samples, a byte each. pts is the time to show or play# it, in 90 kHz ticks since the stream's first frame of that kind.type Frame is Data:  Video{pts: U32, key: Bool, data: List<&2, U32>}  Audio{pts: U32, data: List<&2, U32>}def Frame.pts(f: Frame) -> U32:  match f:    case Video{pts, _, _}:      pts    case Audio{pts, _}:      pts# The frame d ticks later: for a stream that goes on after another.def Frame.later(f: Frame, d: U32) -> Frame:  match f:    case Video{pts, key, data}:      Video{U32.add(pts, d), key, data}    case Audio{pts, data}:      Audio{U32.add(pts, d), data}# A stream's description: the video's codec ("H264" or "H265") and its# parameter sets in Annex B form, as the server announced them (they# may also come in the stream); the audio's codec ("AAC", "PCMA" or# "PCMU" for G.711's A-law and mu-law; "" when there is none this# client reads), its sample rate and channels.type Info is Data:  Info{codec: String, sets: List<&2, U32>, audio: String, rate: U32, chans: U32}def Info.codec(i: Info) -> String:  Info{c, _, _, _, _} = i  cdef Info.sets(i: Info) -> List<&2, U32>:  Info{_, s, _, _, _} = i  sdef Info.audio(i: Info) -> String:  Info{_, _, a, _, _} = i  adef Info.rate(i: Info) -> U32:  Info{_, _, _, r, _} = i  rdef Info.chans(i: Info) -> U32:  Info{_, _, _, _, c} = i  cdef Info.h265(i: Info) -> Bool:  String.eq(Info.codec(i), "H265")