ncw 0.4.0

Native Instruments NCW audio file format support
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146

use ncw::{NcwReader, PcmSpec, StereoMode, encode_pcm, encode_pcm_with_template};
use std::io::Cursor;
fn spec(depth: u16) -> PcmSpec {
    PcmSpec {
        channels: 2,
        bits_per_sample: depth,
        sample_rate: 48000,
    }
}
fn decode(data: &[u8]) -> Vec<i32> {
    NcwReader::read(Cursor::new(data))
        .unwrap()
        .decode_samples()
        .unwrap()
}
#[test]
fn fresh_pcm_extremes_partial_blocks_and_modes() {
    for depth in [16, 24] {
        for frames in [0, 1, 511, 512, 513] {
            for mode in [StereoMode::Direct, StereoMode::Auto, StereoMode::MidSide] {
                let limit = 1 << (depth - 1);
                let pcm: Vec<i32> = (0..frames)
                    .flat_map(|i| {
                        let v = if i % 2 == 0 { -limit } else { limit - 1 };
                        [v, v]
                    })
                    .collect();
                let bytes = encode_pcm(&pcm, spec(depth), mode).unwrap();
                assert_eq!(decode(&bytes), pcm);
                assert_eq!(
                    encode_pcm_with_template(&pcm, spec(depth), &bytes).unwrap(),
                    bytes
                );
            }
        }
    }
}
#[test]
fn parity_is_never_silently_rounded() {
    let pcm = vec![3, 0, 4, 1];
    assert!(encode_pcm(&pcm, spec(16), StereoMode::MidSide).is_err());
    assert_eq!(
        decode(&encode_pcm(&pcm, spec(16), StereoMode::Auto).unwrap()),
        pcm
    );
}
#[test]
fn template_rebuilds_payload_instead_of_copying_it() {
    let pcm: Vec<i32> = (0..513).flat_map(|i| [i * 2, i * 2]).collect();
    let mut original = encode_pcm(&pcm, spec(16), StereoMode::MidSide).unwrap();
    original[40] = 0xaa; // opaque header survives
    original.extend([1, 2, 3]); // trailing bytes survive
    let mut changed = pcm.clone();
    changed[0] += 2;
    changed[1] += 2;
    let output = encode_pcm_with_template(&changed, spec(16), &original).unwrap();
    assert_ne!(output, original);
    assert_eq!(decode(&output), changed);
    assert_eq!(output[40], 0xaa);
    assert!(output.ends_with(&[1, 2, 3]));
    changed[0] = 32767;
    assert!(encode_pcm_with_template(&changed, spec(16), &original).is_err());
}
#[test]
fn shipped_pcm_fixtures_are_byte_identical() {
    let dir = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("tests/data");
    for name in [
        "16-bit-mono",
        "16-bit-stereo",
        "24-bit-mono",
        "24-bit-stereo",
        "testfile-onezero-16-bit-stereo",
        "testfile-onezero-16-bit-stereo-multiblock",
    ] {
        let bytes = std::fs::read(dir.join(format!("{name}.ncw"))).unwrap();
        let mut reader = NcwReader::read(Cursor::new(&bytes)).unwrap();
        let s = PcmSpec {
            channels: reader.header.channels,
            bits_per_sample: reader.header.bits_per_sample,
            sample_rate: reader.header.sample_rate,
        };
        let pcm = reader.decode_samples().unwrap();
        assert_eq!(
            encode_pcm_with_template(&pcm, s, &bytes).unwrap(),
            bytes,
            "{name}"
        );
    }
}
#[test]
fn first_channel_controls_stereo_transform() {
    let pcm = vec![12, 8];
    let bytes = encode_pcm(&pcm, spec(16), StereoMode::MidSide).unwrap();
    let start = u32::from_le_bytes(bytes[24..28].try_into().unwrap()) as usize;
    let bits = i16::from_le_bytes(bytes[start + 8..start + 10].try_into().unwrap());
    let second = start + 16 + bits as usize * 64;
    let mut first_only = bytes.clone();
    first_only[second + 10] = 0;
    assert_eq!(decode(&first_only), pcm);
    let mut second_only = bytes;
    second_only[start + 10] = 0;
    assert_eq!(decode(&second_only), vec![10, 2]);
}
#[test]
fn malformed_templates_rejected_without_panics() {
    let pcm = vec![2, 2];
    let bytes = encode_pcm(&pcm, spec(16), StereoMode::Auto).unwrap();
    for cut in 0..bytes.len() {
        assert!(encode_pcm_with_template(&pcm, spec(16), &bytes[..cut]).is_err());
    }
    let mut bad = bytes.clone();
    bad[124..128].copy_from_slice(&0u32.to_le_bytes());
    assert!(encode_pcm_with_template(&pcm, spec(16), &bad).is_err());
    let mut bad = bytes;
    bad[138] = 2;
    assert!(encode_pcm_with_template(&pcm, spec(16), &bad).is_err());
}

#[test]
fn one_bit_delta_encoding_is_avoided() {
    let pcm = vec![0, 0, -1, -1];
    let bytes = encode_pcm(&pcm, spec(16), StereoMode::Auto).unwrap();
    let start = u32::from_le_bytes(bytes[24..28].try_into().unwrap()) as usize;
    assert_eq!(
        i16::from_le_bytes(bytes[start + 8..start + 10].try_into().unwrap()),
        2
    );
}

#[test]
fn raw_fallback_uses_kontakt_negative_full_depth() {
    for depth in [16, 24] {
        let limit = 1 << (depth - 1);
        let pcm = vec![-limit, -limit, limit - 1, limit - 1];
        let bytes = encode_pcm(&pcm, spec(depth), StereoMode::Direct).unwrap();
        let start = u32::from_le_bytes(bytes[24..28].try_into().unwrap()) as usize;
        assert_eq!(
            i16::from_le_bytes(bytes[start + 8..start + 10].try_into().unwrap()),
            -(depth as i16)
        );
        assert_eq!(decode(&bytes), pcm);
        let mut zero_width = bytes.clone();
        zero_width[start + 8..start + 10].copy_from_slice(&0i16.to_le_bytes());
        assert!(encode_pcm_with_template(&pcm, spec(depth), &zero_width).is_err());
    }
}