`nx_nv1.nx` source

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1// nx_nv1.nx -- NishiLossless v1 (NLC1) circle container: writer + validator.
2//
3// The named exceed rung from the video session: circles recorded LOSSLESSLY
4// (Int16 PCM at the device's NATIVE rate -- the same no-resample doctrine as
5// live call audio) + JPEG frames, in OUR OWN container.  MediaRecorder/webm/
6// opus is gone from the record path.  The browser client (app.js nv1Pack/
7// nv1Parse) implements this same format; THIS module is the team-side
8// authority: the gate proves the format, and the daemon can later validate
9// uploads server-side with nv1_validate.
10//
11// Format (all little-endian):
12//   header (24B): "NLC1" | u32 version=1 | u32 sample_rate | u32 channels=1
13//                 | u32 reserved | u32 reserved
14//   chunk  (9B + payload): u8 kind | u32 len | u32 t_ms | payload
15//     kind 0x41 'A': Int16 PCM mono (len bytes = 2*samples), t_ms derived
16//                    from the running SAMPLE COUNT (sample-exact, not clock)
17//     kind 0x56 'V': one JPEG frame, t_ms = capture time
18//     kind 0x4C 'L': LPC-compressed Int16 PCM (see nx_nv1_lpc.nx; payload
19//                    starts u8 mode | u8 k | u32 nsamples), counts toward
20//                    audio chunks + total samples like 'A'
21//     kind 0x45 'E': terminator, len MUST be 0, t_ms = total duration
22//   The terminator must be the FINAL bytes of the container (no trailing).
23//
24// FLAC-class LPC compression of the PCM (the named next rung) now lives in
25// nx_nv1_lpc.nx as chunk kind 'L'; 'A' remains valid (raw path + back-compat).
26// license_tier: ORIGINAL
27
28import "nx_syscalls.nx"
29const NV1_MAGIC_65536: i64 = 65536
30const NV1_MAGIC_16777216: i64 = 16777216
31
32const NV1_HDR: i64 = 24
33const NV1_CHDR: i64 = 9
34
35func nv1_rd_u32(b: *u8, off: i64) -> i64 {
36    var v: i64 = b[off] & 0xff
37    v = v + ((b[off + 1] & 0xff) * 256)
38    v = v + ((b[off + 2] & 0xff) * NV1_MAGIC_65536)
39    v = v + ((b[off + 3] & 0xff) * NV1_MAGIC_16777216)
40    return v
41}
42
43func nv1_wr_u32(b: *u8, off: i64, v: i64) -> i64 {
44    b[off] = (v & 255) as u8
45    b[off + 1] = ((v / 256) & 255) as u8
46    b[off + 2] = ((v / NV1_MAGIC_65536) & 255) as u8
47    b[off + 3] = ((v / NV1_MAGIC_16777216) & 255) as u8
48    return 4
49}
50
51func nv1_write_header(out: *u8, rate: i64) -> i64 {
52    out[0] = 78; out[1] = 76; out[2] = 67; out[3] = 49      // "NLC1"
53    nv1_wr_u32(out, 4, 1)
54    nv1_wr_u32(out, 8, rate)
55    nv1_wr_u32(out, 12, 1)
56    nv1_wr_u32(out, 16, 0)
57    nv1_wr_u32(out, 20, 0)
58    return NV1_HDR
59}
60
61// append one chunk at write cursor w; returns the new cursor
62func nv1_write_chunk(out: *u8, w: i64, kind: i64, t_ms: i64, payload: *u8, n: i64) -> i64 {
63    out[w] = kind as u8
64    nv1_wr_u32(out, w + 1, n)
65    nv1_wr_u32(out, w + 5, t_ms)
66    var i: i64 = 0
67    while i < n { out[w + NV1_CHDR + i] = payload[i]; i = i + 1 }
68    return w + NV1_CHDR + n
69}
70
71func nv1_write_end(out: *u8, w: i64, dur_ms: i64) -> i64 {
72    out[w] = 69                                              // 'E'
73    nv1_wr_u32(out, w + 1, 0)
74    nv1_wr_u32(out, w + 5, dur_ms)
75    return w + NV1_CHDR
76}
77
78// Validate a complete container.  info[0]=rate info[1]=audio_chunks
79// info[2]=total_samples info[3]=video_frames info[4]=duration_ms.
80// 0 = OK; negatives name the defect:
81//  -1 too short  -2 bad magic  -3 bad version  -4 bad chunk kind / nonzero-E
82//  -5 chunk overruns buffer  -6 missing terminator  -7 channels != 1
83//  -8 trailing bytes after terminator  -9 L chunk payload shorter than its
84//     6-byte sub-header (mode/k/nsamples)
85func nv1_validate(buf: *u8, n: i64, info: *i64) -> i64 {
86    if n < NV1_HDR + NV1_CHDR { return 0 - 1 }
87    var m: i64 = 1
88    if (buf[0] & 0xff) != 78 { m = 0 }
89    if (buf[1] & 0xff) != 76 { m = 0 }
90    if (buf[2] & 0xff) != 67 { m = 0 }
91    if (buf[3] & 0xff) != 49 { m = 0 }
92    if m == 0 { return 0 - 2 }
93    if nv1_rd_u32(buf, 4) != 1 { return 0 - 3 }
94    if nv1_rd_u32(buf, 12) != 1 { return 0 - 7 }
95    info[0] = nv1_rd_u32(buf, 8)
96    var off: i64 = NV1_HDR
97    var ac: i64 = 0
98    var vc: i64 = 0
99    var samp: i64 = 0
100    var dur: i64 = 0
101    var ended: i64 = 0
102    while ended == 0 {
103        if off + NV1_CHDR > n { return 0 - 6 }
104        let k: i64 = buf[off] & 0xff
105        let ln: i64 = nv1_rd_u32(buf, off + 1)
106        let tm: i64 = nv1_rd_u32(buf, off + 5)
107        if off + NV1_CHDR + ln > n { return 0 - 5 }
108        var known: i64 = 0
109        if k == 65 { ac = ac + 1; samp = samp + ln / 2; known = 1 }
110        if k == 76 {
111            if ln < 6 { return 0 - 9 }
112            ac = ac + 1
113            samp = samp + nv1_rd_u32(buf, off + NV1_CHDR + 2)
114            known = 1
115        }
116        if k == 86 { vc = vc + 1; known = 1 }
117        if k == 69 {
118            if ln != 0 { return 0 - 4 }
119            ended = 1; dur = tm; known = 1
120        }
121        if known == 0 { return 0 - 4 }
122        off = off + NV1_CHDR + ln
123    }
124    if off != n { return 0 - 8 }
125    info[1] = ac
126    info[2] = samp
127    info[3] = vc
128    info[4] = dur
129    return 0
130}
nx_nv1.nx source

`nx_nv1.nx` source
