1. 1use super::VoiceError;
2. 2
3. 3/// The socket's only audio shape: mono 16-bit little-endian PCM at 16 kHz.
4. 4pub const SOCKET_SAMPLE_RATE_HZ: u32 = 16_000;
5. 5
6. 6#[derive(Debug, Clone, Copy, PartialEq, Eq)]
7. 7pub struct PcmSpec {
8. 8 pub sample_rate_hz: u32,
9. 9 pub channels: u16,
10. 10}
11. 11
12. 12impl PcmSpec {
13. 13 pub const SOCKET: Self = Self {
14. 14 sample_rate_hz: SOCKET_SAMPLE_RATE_HZ,
15. 15 channels: 1,
16. 16 };
17. 17}
18. 18
19. 19pub fn wrap_wav(pcm: &[u8], spec: PcmSpec) -> Result<Vec<u8>, VoiceError> {
20. 20 if spec.channels == 0 || spec.sample_rate_hz == 0 || !pcm.len().is_multiple_of(2) {
21. 21 return Err(VoiceError::InvalidRequest("invalid PCM stream".into()));
22. 22 }
23. 23 let data_len = u32::try_from(pcm.len())
24. 24 .map_err(|_| VoiceError::InvalidRequest("audio too large".into()))?;
25. 25 let byte_rate = spec.sample_rate_hz * u32::from(spec.channels) * 2;
26. 26 let block_align = spec.channels * 2;
27. 27 let mut out = Vec::with_capacity(44 + pcm.len());
28. 28 out.extend_from_slice(b"RIFF");
29. 29 out.extend_from_slice(&(36 + data_len).to_le_bytes());
30. 30 out.extend_from_slice(b"WAVEfmt ");
31. 31 out.extend_from_slice(&16u32.to_le_bytes());
32. 32 out.extend_from_slice(&1u16.to_le_bytes());
33. 33 out.extend_from_slice(&spec.channels.to_le_bytes());
34. 34 out.extend_from_slice(&spec.sample_rate_hz.to_le_bytes());
35. 35 out.extend_from_slice(&byte_rate.to_le_bytes());
36. 36 out.extend_from_slice(&block_align.to_le_bytes());
37. 37 out.extend_from_slice(&16u16.to_le_bytes());
38. 38 out.extend_from_slice(b"data");
39. 39 out.extend_from_slice(&data_len.to_le_bytes());
40. 40 out.extend_from_slice(pcm);
41. 41 Ok(out)
42. 42}
43. 43
44. 44#[cfg(test)]
45. 45#[allow(clippy::expect_used, clippy::unwrap_used)]
46. 46mod tests {
47. 47 use super::*;
48. 48 #[test]
49. 49 fn wav_header_is_canonical() {
50. 50 let wav = wrap_wav(&[0, 0, 255, 127], PcmSpec::SOCKET).unwrap();
51. 51 assert_eq!(&wav[0..4], b"RIFF");
52. 52 assert_eq!(&wav[8..12], b"WAVE");
53. 53 assert_eq!(&wav[40..44], &[4, 0, 0, 0]);
54. 54 }
55. 55}
56. 56