spdl.io.async_sample_decode_video

async async_sample_decode_video(packets: VideoPackets, indices: list[int], *, decode_config: DecodeConfig | None = None, filter_desc: str | None = '__PLACEHOLDER__', strict: bool = True) → list[ImagePackets][source]

Decode specified frames from the packets.

This function decodes the input video packets and returns the frames specified by indices. Internally, it splits the packets into smaller set of packets and decode the minimum number of frames to retrieve the specified frames.

block-beta columns 15 A["Input Packets"]:15 space:15 block:B1:3 columns 3 P1["1"] P2["2"] P3["3"] end block:B2:3 columns 3 P4["4"] P5["5"] P6["6"] end block:B3:3 columns 3 P7["7"] P8["8"] P9["9"] end block:B4:3 columns 3 P10["10"] P11["11"] P12["12"] end block:B5:3 columns 3 P13["13"] P14["14"] P15["15"] end space:15 block:d1:3 columns 3 F1["Frame 1"] space:2 end space:3 block:d2:3 columns 3 F7["Frame 7"] F8["Frame 8"] space end space:3 block:d3:3 columns 3 F13["Frame 13"] F14["Frame 14"] F15["Frame 15"] end space:15 space:6 block:out:3 columns 3 O1["Frame 1"] O8["Frame 8"] O15["Frame 15"] end space:6 A -- "Split 1" --> B1 A -- "Split 2" --> B2 A -- "Split 3" --> B3 A -- "Split 4" --> B4 A -- "Split 5" --> B5 B1 -- "Decode 1" --> d1 B3 -- "Decode 3" --> d2 B5 -- "Decode 5" --> d3 F1 --> O1 F8 --> O8 F15 --> O15

The packet splits are decoded concurrently. The following figure illustrates the timeline of the process.

gantt title Illustration of asynchronous sample decode timeline dateFormat X axisFormat %s section Thread 1 Split Input Packets:split, 0, 3 Decode Split 1 :decode1, after split, 7 Gather and return: gather, after decode2, 14 section Thread 2 Decode Split 3 :decode2, after split, 10 section Thread 3 Decode Split 5 :decode2, after split, 13
Parameters:

  • packets – The input video packets.

  • indices – The list of frame indices.

  • decode_config – Optional: Decode config. See decode_config().

  • filter_desc – Optional: Filter description. See decode_packets() for detail.

  • strict – Optional: If True, raise an error if any of the frames failed to decode.

Returns:

Decoded frames.