FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/mimic.c
Date: 2025-07-28 20:30:09
Exec Total Coverage
Lines: 126 157 80.3%
Functions: 7 8 87.5%
Branches: 59 88 67.0%
Line Branch Exec Source
1 /*
2 * Copyright (C) 2005 Ole André Vadla Ravnås <oleavr@gmail.com>
3 * Copyright (C) 2008 Ramiro Polla
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include <stdint.h>
23
24 #include "libavutil/mem.h"
25 #include "libavutil/mem_internal.h"
26 #include "libavutil/thread.h"
27
28 #include "avcodec.h"
29 #include "blockdsp.h"
30 #include "codec_internal.h"
31 #include "decode.h"
32 #include "get_bits.h"
33 #include "bytestream.h"
34 #include "bswapdsp.h"
35 #include "hpeldsp.h"
36 #include "idctdsp.h"
37 #include "progressframe.h"
38 #include "thread.h"
39
40 #define MIMIC_HEADER_SIZE 20
41 #define MIMIC_VLC_BITS 11
42
43 typedef struct MimicContext {
44 AVCodecContext *avctx;
45
46 int num_vblocks[3];
47 int num_hblocks[3];
48
49 void *swap_buf;
50 int swap_buf_size;
51
52 int cur_index;
53 int prev_index;
54
55 ProgressFrame frames[16];
56
57 DECLARE_ALIGNED(32, int16_t, dct_block)[64];
58
59 GetBitContext gb;
60 uint8_t permutated_scantable[64];
61 BlockDSPContext bdsp;
62 BswapDSPContext bbdsp;
63 HpelDSPContext hdsp;
64 IDCTDSPContext idsp;
65
66 /* Kept in the context so multithreading can have a constant to read from */
67 int next_cur_index;
68 int next_prev_index;
69 } MimicContext;
70
71 static VLCElem block_vlc[4368];
72
73 static const uint8_t huffsyms[] = {
74 0x10, 0x20, 0x30, 0x00, 0x11, 0x40, 0x50, 0x12, 0x13, 0x21, 0x31, 0x60,
75 0x14, 0x15, 0x16, 0x22, 0x41, 0x17, 0x18, 0x23, 0x24, 0x25, 0x32, 0x42,
76 0x51, 0x61, 0x70, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x26, 0x27,
77 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x33, 0x34, 0x35, 0x36, 0x37,
78 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x43, 0x44, 0x45, 0x46, 0x47,
79 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x52, 0x53, 0x54, 0x55, 0x56,
80 0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x62, 0x63, 0x64, 0x65,
81 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x71, 0x72, 0x73,
82 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E,
83 };
84
85 static const uint8_t huffbits[] = {
86 2, 2, 3, 4, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8,
87 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12,
88 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17,
89 17, 17, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21,
90 22, 22, 22, 22, 23, 23, 23, 23, 24, 24, 24, 24, 25, 25, 25, 25, 26, 26,
91 26, 26, 27, 27, 27, 27, 28, 28, 28, 28, 29, 29, 29, 29, 30, 30, 30,
92 };
93
94 static const uint8_t col_zag[64] = {
95 0, 8, 1, 2, 9, 16, 24, 17,
96 10, 3, 4, 11, 18, 25, 32, 40,
97 33, 26, 19, 12, 5, 6, 13, 20,
98 27, 34, 41, 48, 56, 49, 42, 35,
99 28, 21, 14, 7, 15, 22, 29, 36,
100 43, 50, 57, 58, 51, 44, 37, 30,
101 23, 31, 38, 45, 52, 59, 39, 46,
102 53, 60, 61, 54, 47, 55, 62, 63,
103 };
104
105 2 static av_cold int mimic_decode_end(AVCodecContext *avctx)
106 {
107 2 MimicContext *ctx = avctx->priv_data;
108
109 2 av_freep(&ctx->swap_buf);
110 2 ctx->swap_buf_size = 0;
111
112
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 34 for (int i = 0; i < FF_ARRAY_ELEMS(ctx->frames); i++)
113 32 ff_progress_frame_unref(&ctx->frames[i]);
114
115 2 return 0;
116 }
117
118 1 static av_cold void mimic_init_static(void)
119 {
120 1 VLC_INIT_STATIC_TABLE_FROM_LENGTHS(block_vlc, MIMIC_VLC_BITS,
121 FF_ARRAY_ELEMS(huffbits),
122 huffbits, 1, huffsyms, 1, 1, 0, 0);
123 1 }
124
125 2 static av_cold int mimic_decode_init(AVCodecContext *avctx)
126 {
127 static AVOnce init_static_once = AV_ONCE_INIT;
128 2 MimicContext *ctx = avctx->priv_data;
129
130 2 ctx->prev_index = 0;
131 2 ctx->cur_index = 15;
132
133 2 ff_blockdsp_init(&ctx->bdsp);
134 2 ff_bswapdsp_init(&ctx->bbdsp);
135 2 ff_hpeldsp_init(&ctx->hdsp, avctx->flags);
136 2 ff_idctdsp_init(&ctx->idsp, avctx);
137 2 ff_permute_scantable(ctx->permutated_scantable, col_zag, ctx->idsp.idct_permutation);
138
139 2 ff_thread_once(&init_static_once, mimic_init_static);
140
141 2 return 0;
142 }
143
144 #if HAVE_THREADS
145 ✗ static int mimic_decode_update_thread_context(AVCodecContext *avctx, const AVCodecContext *avctx_from)
146 {
147 ✗ MimicContext *dst = avctx->priv_data, *src = avctx_from->priv_data;
148
149 ✗ if (avctx == avctx_from)
150 ✗ return 0;
151
152 ✗ dst->cur_index = src->next_cur_index;
153 ✗ dst->prev_index = src->next_prev_index;
154
155 ✗ for (int i = 0; i < FF_ARRAY_ELEMS(dst->frames); i++) {
156 ✗ ff_progress_frame_unref(&dst->frames[i]);
157 ✗ if (i != src->next_cur_index && src->frames[i].f)
158 ✗ ff_progress_frame_ref(&dst->frames[i], &src->frames[i]);
159 }
160
161 ✗ return 0;
162 }
163 #endif
164
165 static const int8_t vlcdec_lookup[9][64] = {
166 { 0, },
167 { -1, 1, },
168 { -3, 3, -2, 2, },
169 { -7, 7, -6, 6, -5, 5, -4, 4, },
170 { -15, 15, -14, 14, -13, 13, -12, 12,
171 -11, 11, -10, 10, -9, 9, -8, 8, },
172 { -31, 31, -30, 30, -29, 29, -28, 28,
173 -27, 27, -26, 26, -25, 25, -24, 24,
174 -23, 23, -22, 22, -21, 21, -20, 20,
175 -19, 19, -18, 18, -17, 17, -16, 16, },
176 { -63, 63, -62, 62, -61, 61, -60, 60,
177 -59, 59, -58, 58, -57, 57, -56, 56,
178 -55, 55, -54, 54, -53, 53, -52, 52,
179 -51, 51, -50, 50, -49, 49, -48, 48,
180 -47, 47, -46, 46, -45, 45, -44, 44,
181 -43, 43, -42, 42, -41, 41, -40, 40,
182 -39, 39, -38, 38, -37, 37, -36, 36,
183 -35, 35, -34, 34, -33, 33, -32, 32, },
184 { -127, 127, -126, 126, -125, 125, -124, 124,
185 -123, 123, -122, 122, -121, 121, -120, 120,
186 -119, 119, -118, 118, -117, 117, -116, 116,
187 -115, 115, -114, 114, -113, 113, -112, 112,
188 -111, 111, -110, 110, -109, 109, -108, 108,
189 -107, 107, -106, 106, -105, 105, -104, 104,
190 -103, 103, -102, 102, -101, 101, -100, 100,
191 -99, 99, -98, 98, -97, 97, -96, 96, },
192 { -95, 95, -94, 94, -93, 93, -92, 92,
193 -91, 91, -90, 90, -89, 89, -88, 88,
194 -87, 87, -86, 86, -85, 85, -84, 84,
195 -83, 83, -82, 82, -81, 81, -80, 80,
196 -79, 79, -78, 78, -77, 77, -76, 76,
197 -75, 75, -74, 74, -73, 73, -72, 72,
198 -71, 71, -70, 70, -69, 69, -68, 68,
199 -67, 67, -66, 66, -65, 65, -64, 64, },
200 };
201
202 44548 static int vlc_decode_block(MimicContext *ctx, int num_coeffs, int qscale)
203 {
204 44548 int16_t *block = ctx->dct_block;
205 unsigned int pos;
206
207 44548 ctx->bdsp.clear_block(block);
208
209 44548 block[0] = get_bits(&ctx->gb, 8) << 3;
210
211
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 304893 for (pos = 1; pos < num_coeffs; pos++) {
212 uint32_t vlc, num_bits;
213 int value;
214 int coeff;
215
216 302169 vlc = get_vlc2(&ctx->gb, block_vlc, MIMIC_VLC_BITS, 3);
217
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 302169 if (!vlc) /* end-of-block code */
218 41824 return 0;
219
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 260345 if (vlc == -1)
220 ✗ return AVERROR_INVALIDDATA;
221
222 /* pos_add and num_bits are coded in the vlc code */
223 260345 pos += vlc & 15; // pos_add
224 260345 num_bits = vlc >> 4; // num_bits
225
226
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 260345 if (pos >= 64)
227 ✗ return AVERROR_INVALIDDATA;
228
229 260345 value = get_bits(&ctx->gb, num_bits);
230
231 /* FFmpeg's IDCT behaves somewhat different from the original code, so
232 * a factor of 4 was added to the input */
233
234 260345 coeff = ((int8_t*)vlcdec_lookup[num_bits])[value];
235
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 260345 if (pos < 3)
236 50048 coeff *= 16;
237 else /* TODO Use >> 10 instead of / 1001 */
238 210297 coeff = (coeff * qscale) / 1001;
239
240 260345 block[ctx->permutated_scantable[pos]] = coeff;
241 }
242
243 2724 return 0;
244 }
245
246 77 static int decode(MimicContext *ctx, int quality, int num_coeffs,
247 int is_iframe)
248 {
249 77 int ret, y, x, plane, cur_row = 0;
250
251
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 308 for (plane = 0; plane < 3; plane++) {
252 231 const int is_chroma = !!plane;
253
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 231 const int qscale = av_clip(10000 - quality, is_chroma ? 1000 : 2000,
254 10000) << 2;
255 231 const int stride = ctx->frames[ctx->cur_index ].f->linesize[plane];
256 231 uint8_t *dst = ctx->frames[ctx->cur_index ].f->data[plane];
257 /* src is unused for I frames; set to avoid UB pointer arithmetic. */
258
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 231 const uint8_t *src = is_iframe ? dst : ctx->frames[ctx->prev_index].f->data[plane];
259
260
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 4851 for (y = 0; y < ctx->num_vblocks[plane]; y++) {
261
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 143220 for (x = 0; x < ctx->num_hblocks[plane]; x++) {
262 /* Check for a change condition in the current block.
263 * - iframes always change.
264 * - Luma plane changes on get_bits1 == 0
265 * - Chroma planes change on get_bits1 == 1 */
266
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 138600 if (is_iframe || get_bits1(&ctx->gb) == is_chroma) {
267 /* Luma planes may use a backreference from the 15 last
268 * frames preceding the previous. (get_bits1 == 1)
269 * Chroma planes don't use backreferences. */
270
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 50491 if (is_chroma || is_iframe || !get_bits1(&ctx->gb)) {
271
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 44548 if ((ret = vlc_decode_block(ctx, num_coeffs,
272 qscale)) < 0) {
273 ✗ av_log(ctx->avctx, AV_LOG_ERROR, "Error decoding "
274 "block.\n");
275 ✗ return ret;
276 }
277 44548 ctx->idsp.idct_put(dst, stride, ctx->dct_block);
278 } else {
279 5943 unsigned int backref = get_bits(&ctx->gb, 4);
280 5943 int index = (ctx->cur_index + backref) & 15;
281
282
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 11886 if (index != ctx->cur_index && ctx->frames[index].f) {
283 5943 const uint8_t *p = ctx->frames[index].f->data[0];
284 5943 ff_progress_frame_await(&ctx->frames[index], cur_row);
285 5943 p += src -
286 5943 ctx->frames[ctx->prev_index].f->data[plane];
287 5943 ctx->hdsp.put_pixels_tab[1][0](dst, p, stride, 8);
288 } else {
289 ✗ av_log(ctx->avctx, AV_LOG_ERROR,
290 "No such backreference! Buggy sample.\n");
291 }
292 }
293 } else {
294 88109 ff_progress_frame_await(&ctx->frames[ctx->prev_index], cur_row);
295 88109 ctx->hdsp.put_pixels_tab[1][0](dst, src, stride, 8);
296 }
297 138600 src += 8;
298 138600 dst += 8;
299 }
300 4620 src += (stride - ctx->num_hblocks[plane]) << 3;
301 4620 dst += (stride - ctx->num_hblocks[plane]) << 3;
302
303 4620 ff_progress_frame_report(&ctx->frames[ctx->cur_index], cur_row++);
304 }
305 }
306
307 77 return 0;
308 }
309
310 /**
311 * Flip the buffer upside-down and put it in the YVU order to revert the
312 * way Mimic encodes frames.
313 */
314 77 static void flip_swap_frame(AVFrame *f)
315 {
316 int i;
317 77 uint8_t *data_1 = f->data[1];
318 77 f->data[0] = f->data[0] + ( f->height - 1) * f->linesize[0];
319 77 f->data[1] = f->data[2] + ((f->height >> 1) - 1) * f->linesize[2];
320 77 f->data[2] = data_1 + ((f->height >> 1) - 1) * f->linesize[1];
321
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 308 for (i = 0; i < 3; i++)
322 231 f->linesize[i] *= -1;
323 77 }
324
325 77 static int mimic_decode_frame(AVCodecContext *avctx, AVFrame *rframe,
326 int *got_frame, AVPacket *avpkt)
327 {
328 77 const uint8_t *buf = avpkt->data;
329 77 int buf_size = avpkt->size;
330 77 int swap_buf_size = buf_size - MIMIC_HEADER_SIZE;
331 77 MimicContext *ctx = avctx->priv_data;
332 GetByteContext gb;
333 int is_pframe;
334 int width, height;
335 int quality, num_coeffs;
336 int res;
337
338
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 77 if (buf_size <= MIMIC_HEADER_SIZE) {
339 ✗ av_log(avctx, AV_LOG_ERROR, "insufficient data\n");
340 ✗ return AVERROR_INVALIDDATA;
341 }
342
343 77 bytestream2_init(&gb, buf, MIMIC_HEADER_SIZE);
344 77 bytestream2_skip(&gb, 2); /* some constant (always 256) */
345 77 quality = bytestream2_get_le16u(&gb);
346 77 width = bytestream2_get_le16u(&gb);
347 77 height = bytestream2_get_le16u(&gb);
348 77 bytestream2_skip(&gb, 4); /* some constant */
349 77 is_pframe = bytestream2_get_le32u(&gb);
350 77 num_coeffs = bytestream2_get_byteu(&gb);
351 77 bytestream2_skip(&gb, 3); /* some constant */
352
353
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 77 if (!ctx->avctx) {
354 int i;
355
356
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 2 if (!(width == 160 && height == 120) &&
357
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 2 !(width == 320 && height == 240)) {
358 ✗ av_log(avctx, AV_LOG_ERROR, "invalid width/height!\n");
359 ✗ return AVERROR_INVALIDDATA;
360 }
361
362 2 res = ff_set_dimensions(avctx, width, height);
363
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 2 if (res < 0)
364 ✗ return res;
365
366 2 ctx->avctx = avctx;
367 2 avctx->pix_fmt = AV_PIX_FMT_YUV420P;
368
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 8 for (i = 0; i < 3; i++) {
369
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 6 ctx->num_vblocks[i] = AV_CEIL_RSHIFT(height, 3 + !!i);
370
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 6 ctx->num_hblocks[i] = width >> (3 + !!i);
371 }
372
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 75 } else if (width != ctx->avctx->width || height != ctx->avctx->height) {
373 ✗ avpriv_request_sample(avctx, "Resolution changing");
374 ✗ return AVERROR_PATCHWELCOME;
375 }
376
377
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 77 if (is_pframe && !ctx->frames[ctx->prev_index].f) {
378 ✗ av_log(avctx, AV_LOG_ERROR, "decoding must start with keyframe\n");
379 ✗ return AVERROR_INVALIDDATA;
380 }
381
382 77 ff_progress_frame_unref(&ctx->frames[ctx->cur_index]);
383 77 res = ff_progress_frame_get_buffer(avctx, &ctx->frames[ctx->cur_index],
384 AV_GET_BUFFER_FLAG_REF);
385
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 77 if (res < 0)
386 ✗ return res;
387
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 77 ctx->frames[ctx->cur_index].f->pict_type = is_pframe ? AV_PICTURE_TYPE_P :
388 AV_PICTURE_TYPE_I;
389
390 77 ctx->next_prev_index = ctx->cur_index;
391 77 ctx->next_cur_index = (ctx->cur_index - 1) & 15;
392
393 77 ff_thread_finish_setup(avctx);
394
395 77 av_fast_padded_malloc(&ctx->swap_buf, &ctx->swap_buf_size, swap_buf_size);
396
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 77 if (!ctx->swap_buf)
397 ✗ return AVERROR(ENOMEM);
398
399 77 ctx->bbdsp.bswap_buf(ctx->swap_buf,
400 77 (const uint32_t *) (buf + MIMIC_HEADER_SIZE),
401 swap_buf_size >> 2);
402 77 init_get_bits(&ctx->gb, ctx->swap_buf, swap_buf_size << 3);
403
404 77 res = decode(ctx, quality, num_coeffs, !is_pframe);
405 77 ff_progress_frame_report(&ctx->frames[ctx->cur_index], INT_MAX);
406
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 77 if (res < 0) {
407 ✗ if (!(avctx->active_thread_type & FF_THREAD_FRAME))
408 ✗ ff_progress_frame_unref(&ctx->frames[ctx->cur_index]);
409 ✗ return res;
410 }
411
412
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 77 if ((res = av_frame_ref(rframe, ctx->frames[ctx->cur_index].f)) < 0)
413 ✗ return res;
414 77 *got_frame = 1;
415
416 77 flip_swap_frame(rframe);
417
418 77 ctx->prev_index = ctx->next_prev_index;
419 77 ctx->cur_index = ctx->next_cur_index;
420
421 77 return buf_size;
422 }
423
424 const FFCodec ff_mimic_decoder = {
425 .p.name = "mimic",
426 CODEC_LONG_NAME("Mimic"),
427 .p.type = AVMEDIA_TYPE_VIDEO,
428 .p.id = AV_CODEC_ID_MIMIC,
429 .priv_data_size = sizeof(MimicContext),
430 .init = mimic_decode_init,
431 .close = mimic_decode_end,
432 FF_CODEC_DECODE_CB(mimic_decode_frame),
433 .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
434 UPDATE_THREAD_CONTEXT(mimic_decode_update_thread_context),
435 .caps_internal = FF_CODEC_CAP_USES_PROGRESSFRAMES |
436 FF_CODEC_CAP_INIT_CLEANUP,
437 };
438