Module vp8 

VP8 RTP payload helpers.

These helpers operate on the codec payload slice, not on the full RTP packet. In runtime forwarding that slice starts after the RTP fixed header, CSRC list and any RTP header-extension block.

RFC 7741 puts a VP8 payload descriptor in front of the VP8 payload header. The descriptor is also where simulcast and temporal-layer packet identity is carried. o-sfu keeps the RFC constants here, while the runtime uses str0m’s descriptor parser and patch support for local egress.

VP8 payload slice passed to this module

+------------------+----------------------+----------------------+
| descriptor byte  | extension bytes      | VP8 payload header   |
+------------------+----------------------+----------------------+
| X R N S PartID   | I L T K fields       | P bit and VP8 data   |
+------------------+----------------------+----------------------+

Extension bytes when X=1

+-------------+-------------------+-------------+----------------+
| I L T K ... | PictureID if I=1  | TL0 if L=1  | T/K if present |
+-------------+-------------------+-------------+----------------+
|             | 1 or 2 bytes      | 1 byte      | 1 byte         |
+-------------+-------------------+-------------+----------------+

Constants

DIMENSION_MASK 🔒

INTERFRAME_BIT

VP8 payload-header P bit set for interframes.

I_BIT

PictureID present bit in the extended VP8 payload descriptor.

KEYFRAME_SYNC_CODE 🔒

K_BIT 🔒

LONG_PICTURE_ID_BIT

Long PictureID marker bit in the VP8 PictureID field.

LONG_PICTURE_ID_MASK

Value mask for the 15-bit VP8 long PictureID field.

LONG_PICTURE_ID_MODULUS

Modulus for the 15-bit VP8 long PictureID field.

L_BIT

TL0PICIDX present bit in the extended VP8 payload descriptor.

MAX_DEFINED_VERSION 🔒

PARTITION_ID_MASK 🔒

SHORT_PICTURE_ID_MASK

value mask for the 7-bit VP8 short PictureID field

S_BIT

Start of VP8 partition bit in the payload descriptor.

TEMPORAL_LAYER_ID_MASK

Value mask for the two-bit VP8 temporal-layer identity.

T_BIT

TID/Y/KEYIDX present bit in the extended VP8 payload descriptor.

VERSION_MASK 🔒

VERSION_SHIFT 🔒

X_BIT

Extended control bits are present in the VP8 payload descriptor.

Functions

extended_frame_payload 🔒

Locates the VP8 frame bytes after an extended descriptor.

payload_starts_keyframe

Detects a complete VP8 keyframe prefix in the first RTP packet.

valid_keyframe_prefix 🔒