mmids_core/
lib.rs

1//! This crate contains all the building blocks and foundational systems that a mmids application
2//! requires. It also contains standard workflow steps that are likely to be used in most
3//! mmids applications.
4
5extern crate pest;
6#[macro_use]
7extern crate pest_derive;
8
9use rml_rtmp::time::RtmpTimestamp;
10use std::num::Wrapping;
11use std::time::Duration;
12use tracing::error;
13
14pub mod codecs;
15pub mod config;
16pub mod endpoints;
17pub mod event_hub;
18pub mod http_api;
19pub mod net;
20pub mod reactors;
21#[cfg(test)]
22mod test_utils;
23mod utils;
24pub mod workflows;
25
26/// Unique identifier that identifies the flow of video end-to-end.  Normally when media data enters
27/// the beginning of a workflow it will be given a unique stream identifier, and it will keep that
28/// identifier until it leaves the last stage of the workflow.  This allows for logging to give
29/// visibility of how media is processed throughout it's all lifetime.
30///
31/// If a workflow has a step that requires media to leave the system and then come back in for
32/// further steps, than it should keep the same stream identifier.  For example, if
33/// a workflow has an ffmpeg transcoding step in the workflow (e.g. to add a watermark), when
34/// ffmpeg pushes the video back in it will keep the same identifier.
35#[derive(Clone, Debug, PartialEq, Eq, Hash)]
36pub struct StreamId(pub String);
37
38/// Represents timestamps relevant to video data.  Contains the decoding time stamp (dts) and
39/// presentation time stamp (dts).
40#[derive(Clone, Debug, PartialEq)]
41pub struct VideoTimestamp {
42    dts: Duration,
43    pts_offset: i32,
44}
45
46impl VideoTimestamp {
47    /// Creates a new video timestamp from RTMP data.  RTMP packets contain a timestamp in the
48    /// RTMP header itself and a composition time offset in the `AVCVIDEOPACKET` header.  The RTMP
49    /// timestamp is the decoding timestamp (dts), while the composition time offset is added to the
50    /// dts to get the presentation timestamp (pts).
51    pub fn from_rtmp_data(rtmp_timestamp: RtmpTimestamp, mut composition_time_offset: i32) -> Self {
52        if composition_time_offset < -8388608 || composition_time_offset > 8388607 {
53            error!("Composition time offset of {composition_time_offset} is out of 24 bit range.  Leaving at zero");
54            composition_time_offset = 0;
55        }
56
57        VideoTimestamp {
58            dts: Duration::from_millis(rtmp_timestamp.value as u64),
59            pts_offset: composition_time_offset,
60        }
61    }
62
63    /// Creates a new video timestamp based on absolute dts and pts values.
64    pub fn from_durations(dts: Duration, pts: Duration) -> Self {
65        let mut pts_offset = pts.as_millis() as i64 - dts.as_millis() as i64;
66        if pts_offset < -8388608 || pts_offset > 8388607 {
67            error!("PTS ({pts:?}) and DTS ({dts:?}) differ by more than a 24 bit number. Setting pts = dts");
68            pts_offset = 0;
69        }
70
71        VideoTimestamp {
72            dts,
73            pts_offset: pts_offset as i32,
74        }
75    }
76
77    /// Creates a video timestamp at zero
78    pub fn from_zero() -> Self {
79        VideoTimestamp {
80            dts: Duration::new(0, 0),
81            pts_offset: 0,
82        }
83    }
84
85    /// Gets the decoding time stamp for this video packet
86    pub fn dts(&self) -> Duration {
87        self.dts
88    }
89
90    /// Gets the presentation time stamp for the video packet
91    pub fn pts(&self) -> Duration {
92        let mut dts = Wrapping(self.dts.as_millis() as u64);
93        if self.pts_offset > 0 {
94            dts += Wrapping(self.pts_offset as u64);
95        } else {
96            dts -= Wrapping((self.pts_offset * -1) as u64);
97        }
98
99        Duration::from_millis(dts.0)
100    }
101
102    /// Gets the offset from the decoding timestamp for the pts
103    pub fn pts_offset(&self) -> i32 {
104        self.pts_offset
105    }
106}
mmids_core/lib.rs

mmids_core/
lib.rs
