Struct FlexFec03Encoder 

pub struct FlexFec03Encoder { /* private fields */ }

Builds FlexFEC draft-03 repair packets.

Draft-03 rather than RFC 8627 because draft-03 is what browsers negotiate as video/flexfec-03. The RFC states its payload formats are not backward compatible with the earlier drafts, so the two are separate implementations with separate vectors — a draft-03 round trip is evidence about browsers, not about the RFC.

 0                   1                   2                   3
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0|0| P|X|  CC  |M| PT recovery |         length recovery       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                          TS recovery                          |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|   SSRCCount   |                    reserved                   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                             SSRC_i                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|           SN base_i           |k|          Mask [0-14]        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|k|                   Mask [15-45] (optional)                   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|k|                                                             |
+-+                   Mask [46-108] (optional)                  |
|                                                               |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Implementations

impl FlexFec03Encoder

pub fn new(payload_type: u8, ssrc: u32) -> Self

A repair-stream encoder sending payload_type on ssrc.

The repair stream has its own SSRC and its own sequence-number space, both negotiated separately from the media it protects.

pub fn with_base_sequence_number(self, sequence_number: u16) -> Self

Start the repair stream’s sequence numbers at sequence_number.

pub fn next_sequence_number(&self) -> u16

The sequence number the next repair packet will carry.

pub fn encode( &mut self, media_packets: &[Packet], num_fec_packets: u32, ) -> Vec<Packet>

Build up to num_fec_packets repair packets protecting media_packets.

Returns nothing when the media packets are not a consecutive run: a packet mask describes positions relative to one base sequence number, so a gap would silently shift every position after it and protect the wrong packets. A caller that has lost a packet should start a new block rather than encode across the hole.

Trait Implementations

impl Debug for FlexFec03Encoder

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.