Frame format

See the normative layout in spec/transport/frames. Quick reference:

0        4   5   6      8            16           24        28
+--------+---+---+------+------------+------------+---------+
| "AWPF" |ver|flg|chan  | seq (u64)  | ts_mono_ns | len(u32)|
+--------+---+---+------+------------+------------+---------+
                                                             \
  if flg bit 2:  28        30                                 30+ext_len
                 +---------+---------------------------------+----------
                 | ext_len | TLV entries: type u8, len u8, v… | payload…
                 +---------+---------------------------------+----------
  else:          28
                 +----------
                 | payload…

Little-endian throughout. Flags: bit 0 keyframe, bit 1 end-of-burst, bit 2 has_extensions, bit 3 resync (first frame after a discontinuity; always a keyframe), bits 4–7 reserved (zero on send, ignored on receive). Extension types: 0x01 tick (u64), 0x02 ts_sim_ns (i64), 0x03 ts_send_ns (u64), 0x80–0xFF vendor. payload_len counts payload bytes only.

Inline JSON form

In the inline binding the same frame is an obs.frame or cmd.frame notification (AWP-DAT-004):

awp:obs-frame

{ "jsonrpc": "2.0", "method": "obs.frame",
  "params": { "channel_id": 1, "seq": 42, "ts_mono_ns": 913005200000, "flags": 1,
              "tick": 4212, "ts_sim_ns": 4212000000,
              "payload_b64": "eyJhdmF0YXIiOlsyLDNdfQ==" } }

flags in JSON carries bits 0, 1, and 3 only; extension values are the named fields tick, ts_sim_ns, and ts_send_ns (vendor extensions: x-<vendor>.<name>). A streaming observation frame carries its send time (test vector streaming_ts_send):

awp:obs-frame

{ "jsonrpc": "2.0", "method": "obs.frame",
  "params": { "channel_id": 1, "seq": 4211, "ts_mono_ns": 913004112000, "ts_send_ns": 913004120200, "flags": 1,
              "payload_b64": "eyJhdmF0YXIiOlsyLDNdfQ==" } }

Worked example

Keyframe on channel 1, seq 42, ts_mono_ns 913005200000, tick 4212, 16-byte payload (test vector keyframe_tick):

41 57 50 46  01  05  01 00                          magic, version 1, flags 0b101, channel 1
2a 00 00 00 00 00 00 00                             seq = 42
80 c2 59 93 d4 00 00 00                             ts_mono_ns = 913005200000
10 00 00 00                                         payload_len = 16
0a 00                                               ext_len = 10
01 08  74 10 00 00 00 00 00 00                      tick (0x01, len 8) = 4212
7b 22 61 76 61 74 61 72 22 3a 5b 32 2c 33 5d 7d     payload  {"avatar":[2,3]}

All vectors, including the malformed ones a decoder must reject, are in schemas/test-vectors/frames.json and are exercised by the reference decoder in CI (AWP-DAT-008).

Overview

Control channel (JSON-RPC)

Frames

Schemas

Inline JSON form

Worked example

​Inline JSON form

​Worked example

Inline JSON form

Worked example