audio_encoder_test_lib/
timestamp_validator.rs

1// Copyright 2020 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5//! Validations on timestamps of encoded audio packets.
6
7use crate::pcm_audio::*;
8use async_trait::async_trait;
9use stream_processor_test::*;
10
11#[derive(Debug, Clone, Copy)]
12struct Timestamp {
13    input_index: usize,
14    timestamp: u64,
15}
16
17pub struct TimestampValidator {
18    frame_length: usize,
19    pcm_frame_size: usize,
20    timestamp_generator: Option<TimestampGenerator>,
21    timestamps: Vec<Timestamp>,
22}
23
24impl TimestampValidator {
25    /// Given `frame_length`, the input size of encoded output packets in terms of PCM input frames,
26    /// and the input stream, creates a validator that knows what timestamps to expect on each
27    /// encoded output packet.
28    pub fn new(
29        frame_length: usize,
30        pcm_frame_size: usize,
31        timestamp_generator: Option<TimestampGenerator>,
32        audio_stream: &impl ElementaryStream,
33    ) -> Self {
34        let mut input_index = 0;
35        Self {
36            frame_length,
37            pcm_frame_size,
38            timestamp_generator,
39            timestamps: audio_stream
40                .stream()
41                .filter_map(move |chunk| {
42                    chunk.timestamp.map(|timestamp| {
43                        let ts = Timestamp { input_index, timestamp };
44                        input_index += chunk.data.len();
45                        ts
46                    })
47                })
48                .collect(),
49        }
50    }
51
52    pub fn expected_timestamp(&self, output_packet_index: usize) -> Option<u64> {
53        let input_index = output_packet_index * self.frame_length * self.pcm_frame_size;
54        match self.timestamps.binary_search_by_key(&input_index, |ts| ts.input_index) {
55            Ok(i) => {
56                // This is a carried timestamp.
57                Some(self.timestamps[i].timestamp)
58            }
59            Err(i) => {
60                // This is a potentially extrapolated timestamp; `i - 1` is the index of the input
61                // timestamp that most closely precedes this output packet.
62                let preceding = &self.timestamps[i.checked_sub(1)?];
63
64                let delta = input_index - preceding.input_index;
65                if delta >= self.frame_length * self.pcm_frame_size {
66                    // This timestamp has already been extrapolated and should not be
67                    // extrapolated again.
68                    return None;
69                }
70
71                self.timestamp_generator
72                    .as_ref()
73                    .map(|timestamp_generator| timestamp_generator.timestamp_at(delta))
74                    .map(move |time_delta| time_delta + preceding.timestamp)
75            }
76        }
77    }
78}
79
80#[async_trait(?Send)]
81impl OutputValidator for TimestampValidator {
82    async fn validate(&self, output: &[Output]) -> Result<()> {
83        for (i, packet) in output_packets(output).enumerate() {
84            let expected = self.expected_timestamp(i);
85            let actual = packet.packet.timestamp_ish;
86            if actual != expected {
87                Err(FatalError(format!(
88                    "Expected {:?}; got {:?} in {:?}th packet {:#?}",
89                    expected, actual, i, packet.packet
90                )))?;
91            }
92        }
93
94        Ok(())
95    }
96}
audio_encoder_test_lib/timestamp_validator.rs

audio_encoder_test_lib/
timestamp_validator.rs
