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frq_h264.c · 289 lines · 10.7 KBC Blame HistoryRaw
Bind the C libraries a call actually needs 87e5be9 nandi 9d ago1/* A flat C face for openh264's encoder.
2 *
3 * WHY THIS EXISTS. openh264's C API is not flat. `ISVCEncoder` is
4 * `const ISVCEncoderVtbl*` — a pointer to a table of function pointers — so
5 * calling Initialize or EncodeFrame means dereferencing the object, reading a
6 * slot, and calling through it. jolt.ffi cannot do that: Chez fixes a foreign
7 * procedure's types when it COMPILES it, and the target has to be a literal C
8 * symbol name rather than a function pointer (see jolt/ffi.clj, "the target
9 * must be a literal C symbol name"). So the vtable is walked here, in C, and
10 * what jolt binds is the five plain symbols below.
11 *
12 * It is deliberately thin. No policy, no buffering beyond what openh264's own
13 * output demands, and no decisions that belong in frq — the shim exists to
14 * change a calling convention, not to be a video pipeline.
15 *
16 * THE ONE THING IT DOES DO is flatten the output. openh264 hands back an
17 * SFrameBSInfo describing up to MAX_LAYER_NUM_OF_FRAME layers, each with its
18 * own NAL count and a shared bitstream buffer. A caller wanting one Annex B
19 * frame has to walk that; doing it in jolt would mean reading nested C structs
20 * whose layout is openh264's business. It is copied into one contiguous
21 * buffer owned by the encoder handle and handed over as a borrowed span,
22 * valid until the next encode — which is exactly the contract frq.av already
23 * has for a video frame.
24 */
25#include <stdlib.h>
26#include <string.h>
27#include <stdint.h>
28#include <wels/codec_api.h>
29#include <wels/codec_app_def.h>
30
31typedef struct {
32 ISVCEncoder *enc;
33 unsigned char *out; /* flattened Annex B, grown as needed */
34 size_t out_cap;
35 int width, height;
36} frq_h264;
37
38/* Answers 0 on success, or openh264's own non-zero return. */
39int frq_h264_open(int width, int height, int fps, int bitrate, void **handle) {
40 ISVCEncoder *enc = NULL;
41 frq_h264 *h;
42 SEncParamBase p;
43 int rc;
44
45 *handle = NULL;
46 rc = WelsCreateSVCEncoder(&enc);
47 if (rc != 0 || enc == NULL) return rc ? rc : -1;
48
49 memset(&p, 0, sizeof(p));
50 p.iUsageType = CAMERA_VIDEO_REAL_TIME;
51 p.iPicWidth = width;
52 p.iPicHeight = height;
53 p.iTargetBitrate = bitrate;
54 p.fMaxFrameRate = (float)fps;
55
56 rc = (*enc)->Initialize(enc, &p);
57 if (rc != 0) { WelsDestroySVCEncoder(enc); return rc; }
58
59 h = (frq_h264 *)calloc(1, sizeof(frq_h264));
60 if (h == NULL) { (*enc)->Uninitialize(enc); WelsDestroySVCEncoder(enc); return -1; }
61 h->enc = enc; h->width = width; h->height = height;
62 *handle = h;
63 return 0;
64}
65
66/* Encode one I420 frame.
67 *
68 * `i420` is width*height luma followed by two (width/2)*(height/2) planes.
69 * On success answers 0 and sets *out / *out_len to a BORROWED span, valid
70 * until the next call on this handle. *keyframe says whether it is an IDR.
71 * A frame openh264 chose to skip answers 0 with *out_len == 0. */
72int frq_h264_encode(void *handle, const unsigned char *i420, long long pts_us,
73 const unsigned char **out, int *out_len, int *keyframe) {
74 frq_h264 *h = (frq_h264 *)handle;
75 SSourcePicture pic;
76 SFrameBSInfo info;
77 int rc, i, j, total = 0, off = 0;
78
79 *out = NULL; *out_len = 0; *keyframe = 0;
80
81 memset(&pic, 0, sizeof(pic));
82 pic.iPicWidth = h->width;
83 pic.iPicHeight = h->height;
84 pic.iColorFormat = videoFormatI420;
85 pic.iStride[0] = h->width;
86 pic.iStride[1] = h->width / 2;
87 pic.iStride[2] = h->width / 2;
88 pic.pData[0] = (unsigned char *)i420;
89 pic.pData[1] = pic.pData[0] + h->width * h->height;
90 pic.pData[2] = pic.pData[1] + (h->width / 2) * (h->height / 2);
91 pic.uiTimeStamp = pts_us / 1000; /* openh264 counts milliseconds */
92
93 memset(&info, 0, sizeof(info));
94 rc = (*h->enc)->EncodeFrame(h->enc, &pic, &info);
95 if (rc != cmResultSuccess) return rc;
96 if (info.eFrameType == videoFrameTypeSkip) return 0;
97
98 for (i = 0; i < info.iLayerNum; i++)
99 for (j = 0; j < info.sLayerInfo[i].iNalCount; j++)
100 total += info.sLayerInfo[i].pNalLengthInByte[j];
101
102 if ((size_t)total > h->out_cap) {
103 unsigned char *grown = (unsigned char *)realloc(h->out, (size_t)total);
104 if (grown == NULL) return -1;
105 h->out = grown; h->out_cap = (size_t)total;
106 }
107 for (i = 0; i < info.iLayerNum; i++) {
108 int n = 0, k;
109 for (k = 0; k < info.sLayerInfo[i].iNalCount; k++)
110 n += info.sLayerInfo[i].pNalLengthInByte[k];
111 memcpy(h->out + off, info.sLayerInfo[i].pBsBuf, (size_t)n);
112 off += n;
113 }
114
115 *out = h->out;
116 *out_len = total;
117 *keyframe = (info.eFrameType == videoFrameTypeIDR);
118 return 0;
119}
120
121int frq_h264_force_keyframe(void *handle) {
122 frq_h264 *h = (frq_h264 *)handle;
123 return (*h->enc)->ForceIntraFrame(h->enc, true);
124}
125
126void frq_h264_close(void *handle) {
127 frq_h264 *h = (frq_h264 *)handle;
128 if (h == NULL) return;
129 if (h->enc) { (*h->enc)->Uninitialize(h->enc); WelsDestroySVCEncoder(h->enc); }
130 free(h->out);
131 free(h);
132}
Decode H.264 to RGBA, and list the devices av.clj offers 982c702 nandi 9d ago133
134/* --- decoding -------------------------------------------------------------
135 *
136 * Same vtable problem, same answer. ISVCDecoder is `const ISVCDecoderVtbl*`,
137 * so DecodeFrameNoDelay is a function pointer and jolt cannot reach it.
138 *
139 * What comes out is I420 in the decoder's OWN buffers, three planes with
140 * their own strides — which are not the width. A decoder pads its rows, so
141 * copying `width` bytes per row from a `stride`-wide plane is the mistake
142 * that produces a picture sheared diagonally, and it is why the strides are
143 * carried through to the converter below rather than assumed away.
144 */
145#include <wels/codec_def.h>
146
147typedef struct {
148 ISVCDecoder *dec;
149 unsigned char *rgba; /* converted output, grown as needed */
150 size_t rgba_cap;
151} frq_h264_dec;
152
153int frq_h264_decoder_open(void **handle) {
154 ISVCDecoder *dec = NULL;
155 frq_h264_dec *d;
156 SDecodingParam p;
157 int rc;
158
159 *handle = NULL;
160 rc = WelsCreateDecoder(&dec);
161 if (rc != 0 || dec == NULL) return rc ? rc : -1;
162
163 memset(&p, 0, sizeof(p));
164 p.eEcActiveIdc = ERROR_CON_SLICE_COPY;
165 p.sVideoProperty.eVideoBsType = VIDEO_BITSTREAM_AVC;
166
167 rc = (int)(*dec)->Initialize(dec, &p);
168 if (rc != 0) { WelsDestroyDecoder(dec); return rc; }
169
170 d = (frq_h264_dec *)calloc(1, sizeof(frq_h264_dec));
171 if (d == NULL) { (*dec)->Uninitialize(dec); WelsDestroyDecoder(dec); return -1; }
172 d->dec = dec;
173 *handle = d;
174 return 0;
175}
176
177/* Decode one Annex B frame and convert it to RGBA.
178 *
179 * RGBA rather than I420 because that is what the far end of this is:
180 * vidya/frame-rgba! takes a tightly packed RGBA buffer, and converting here
181 * means the pixels are touched once, in C, instead of crossing into jolt to
182 * be rearranged. On success answers 0; *out is NULL and *w/*h are 0 when the
183 * decoder has no picture yet, which is normal for the first packets. */
184int frq_h264_decode_rgba(void *handle, const unsigned char *annexb, int len,
185 const unsigned char **out, int *w, int *h) {
186 frq_h264_dec *d = (frq_h264_dec *)handle;
187 unsigned char *planes[3] = {NULL, NULL, NULL};
188 SBufferInfo info;
189 DECODING_STATE st;
190 int width, height, y, x, sy, su, sv;
191 size_t need;
192
193 *out = NULL; *w = 0; *h = 0;
194 memset(&info, 0, sizeof(info));
195
196 st = (*d->dec)->DecodeFrameNoDelay(d->dec, annexb, len, planes, &info);
197 if (st != dsErrorFree) return (int)st;
198 if (info.iBufferStatus != 1) return 0; /* no picture this time */
199
200 width = info.UsrData.sSystemBuffer.iWidth;
201 height = info.UsrData.sSystemBuffer.iHeight;
202 sy = info.UsrData.sSystemBuffer.iStride[0];
203 su = info.UsrData.sSystemBuffer.iStride[1];
204 sv = su;
205 if (width <= 0 || height <= 0) return 0;
206
207 need = (size_t)width * (size_t)height * 4u;
208 if (need > d->rgba_cap) {
209 unsigned char *grown = (unsigned char *)realloc(d->rgba, need);
210 if (grown == NULL) return -1;
211 d->rgba = grown; d->rgba_cap = need;
212 }
213
214 /* BT.601 limited range, integer. Not a quality decision worth agonising
215 * over here: it is what a webcam stream is tagged as, and the alternative
216 * is dragging a colour-management dependency in for a video call. */
217 for (y = 0; y < height; y++) {
218 const unsigned char *Y = planes[0] + (size_t)y * sy;
219 const unsigned char *U = planes[1] + (size_t)(y / 2) * su;
220 const unsigned char *V = planes[2] + (size_t)(y / 2) * sv;
221 unsigned char *dst = d->rgba + (size_t)y * width * 4;
222 for (x = 0; x < width; x++) {
223 int c = (int)Y[x] - 16;
224 int u = (int)U[x / 2] - 128;
225 int v = (int)V[x / 2] - 128;
226 int r = (298 * c + 409 * v + 128) >> 8;
227 int g = (298 * c - 100 * u - 208 * v + 128) >> 8;
228 int b = (298 * c + 516 * u + 128) >> 8;
229 dst[x * 4 + 0] = (unsigned char)(r < 0 ? 0 : r > 255 ? 255 : r);
230 dst[x * 4 + 1] = (unsigned char)(g < 0 ? 0 : g > 255 ? 255 : g);
231 dst[x * 4 + 2] = (unsigned char)(b < 0 ? 0 : b > 255 ? 255 : b);
232 dst[x * 4 + 3] = 255;
233 }
234 }
235
236 *out = d->rgba; *w = width; *h = height;
237 return 0;
238}
239
240void frq_h264_decoder_close(void *handle) {
241 frq_h264_dec *d = (frq_h264_dec *)handle;
242 if (d == NULL) return;
243 if (d->dec) { (*d->dec)->Uninitialize(d->dec); WelsDestroyDecoder(d->dec); }
244 free(d->rgba);
245 free(d);
246}
Let the plane take real devices, not only test thunks 596dc29 nandi 9d ago247
248/* --- YUYV to I420 ---------------------------------------------------------
249 *
250 * A webcam almost never hands you I420. YUYV (4:2:2 packed) is the format
251 * every UVC device supports, and openh264 wants I420 (4:2:0 planar), so
252 * something has to transpose and subsample between them. Doing it in jolt
253 * would be a per-pixel loop through ffi/read and ffi/write at thirty frames
254 * a second; doing it here is one pass over the row pairs.
255 *
256 * The chroma is AVERAGED down the row pair rather than dropped. Taking every
257 * other line instead is a line cheaper and shows up as combing on anything
258 * with a hard colour edge — a red shirt against a pale wall is the usual
259 * way to see it.
260 *
261 * `src` is width*height*2 bytes; `dst` is width*height*3/2. Both even
262 * dimensions, which V4L2 will have negotiated anyway.
263 */
264void frq_yuyv_to_i420(const unsigned char *src, unsigned char *dst,
265 int width, int height) {
266 int x, y;
267 unsigned char *Y = dst;
268 unsigned char *U = dst + width * height;
269 unsigned char *V = U + (width / 2) * (height / 2);
270
271 for (y = 0; y < height; y++) {
272 const unsigned char *row = src + (size_t)y * width * 2;
273 unsigned char *yr = Y + (size_t)y * width;
274 for (x = 0; x < width; x++) yr[x] = row[x * 2];
275 }
276 for (y = 0; y < height; y += 2) {
277 const unsigned char *r0 = src + (size_t)y * width * 2;
278 const unsigned char *r1 = src + (size_t)(y + 1) * width * 2;
279 unsigned char *ur = U + (size_t)(y / 2) * (width / 2);
280 unsigned char *vr = V + (size_t)(y / 2) * (width / 2);
281 for (x = 0; x < width; x += 2) {
282 /* One U and one V per two pixels per row; averaged over the pair. */
283 int u = (r0[x * 2 + 1] + r1[x * 2 + 1] + 1) >> 1;
284 int v = (r0[x * 2 + 3] + r1[x * 2 + 3] + 1) >> 1;
285 ur[x / 2] = (unsigned char)u;
286 vr[x / 2] = (unsigned char)v;
287 }
288 }
289}