FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/mpegvideo_parser.c
Date: 2022-01-22 23:30:28
Exec Total Coverage
Lines: 114 121 94.2%
Branches: 58 76 76.3%

Line Branch Exec Source
1 /*
2 * MPEG-1 / MPEG-2 video parser
3 * Copyright (c) 2000,2001 Fabrice Bellard
4 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 #include "parser.h"
24 #include "mpeg12.h"
25 #include "mpeg12data.h"
26 #include "internal.h"
27
28 struct MpvParseContext {
29 ParseContext pc;
30 AVRational frame_rate;
31 int progressive_sequence;
32 int width, height;
33 };
34
35 #if !FF_API_FLAG_TRUNCATED
36 /**
37 * Find the end of the current frame in the bitstream.
38 * @return the position of the first byte of the next frame, or -1
39 */
40 static int mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf,
41 int buf_size, AVCodecParserContext *s)
42 {
43 int i;
44 uint32_t state = pc->state;
45
46 /* EOF considered as end of frame */
47 if (buf_size == 0)
48 return 0;
49
50 /*
51 0 frame start -> 1/4
52 1 first_SEQEXT -> 0/2
53 2 first field start -> 3/0
54 3 second_SEQEXT -> 2/0
55 4 searching end
56 */
57
58 for (i = 0; i < buf_size; i++) {
59 av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
60 if (pc->frame_start_found & 1) {
61 if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
62 pc->frame_start_found--;
63 else if (state == EXT_START_CODE + 2) {
64 if ((buf[i] & 3) == 3)
65 pc->frame_start_found = 0;
66 else
67 pc->frame_start_found = (pc->frame_start_found + 1) & 3;
68 }
69 state++;
70 } else {
71 i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
72 if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
73 i++;
74 pc->frame_start_found = 4;
75 }
76 if (state == SEQ_END_CODE) {
77 pc->frame_start_found = 0;
78 pc->state = -1;
79 return i + 1;
80 }
81 if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
82 pc->frame_start_found = 0;
83 if (pc->frame_start_found < 4 && state == EXT_START_CODE)
84 pc->frame_start_found++;
85 if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
86 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
87 pc->frame_start_found = 0;
88 pc->state = -1;
89 return i - 3;
90 }
91 }
92 if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
93 ff_fetch_timestamp(s, i - 3, 1, i > 3);
94 }
95 }
96 }
97 pc->state = state;
98 return END_NOT_FOUND;
99 }
100 #endif
101
102 8946 static void mpegvideo_extract_headers(AVCodecParserContext *s,
103 AVCodecContext *avctx,
104 const uint8_t *buf, int buf_size)
105 {
106 8946 struct MpvParseContext *pc = s->priv_data;
107 8946 const uint8_t *buf_end = buf + buf_size;
108 uint32_t start_code;
109 int frame_rate_index, ext_type, bytes_left;
110 int frame_rate_ext_n, frame_rate_ext_d;
111 int top_field_first, repeat_first_field, progressive_frame;
112 int horiz_size_ext, vert_size_ext, bit_rate_ext;
113 8946 int did_set_size=0;
114 8946 int set_dim_ret = 0;
115 8946 int bit_rate = 0;
116 8946 int vbv_delay = 0;
117 int chroma_format;
118 8946 enum AVPixelFormat pix_fmt = AV_PIX_FMT_NONE;
119 //FIXME replace the crap with get_bits()
120 8946 s->repeat_pict = 0;
121
122
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32640 while (buf < buf_end) {
123 32387 start_code= -1;
124 32387 buf= avpriv_find_start_code(buf, buf_end, &start_code);
125 32387 bytes_left = buf_end - buf;
126
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32387 switch(start_code) {
127 8676 case PICTURE_START_CODE:
128
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8676 if (bytes_left >= 2) {
129 8676 s->pict_type = (buf[1] >> 3) & 7;
130
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8676 if (bytes_left >= 4)
131 8676 vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3] >> 3);
132 }
133 8676 break;
134 1923 case SEQ_START_CODE:
135
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1923 if (bytes_left >= 7) {
136 1923 pc->width = (buf[0] << 4) | (buf[1] >> 4);
137 1923 pc->height = ((buf[1] & 0x0f) << 8) | buf[2];
138
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1923 if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){
139 168 set_dim_ret = ff_set_dimensions(avctx, pc->width, pc->height);
140 168 did_set_size=1;
141 }
142 1923 pix_fmt = AV_PIX_FMT_YUV420P;
143 1923 frame_rate_index = buf[3] & 0xf;
144 1923 pc->frame_rate = avctx->framerate = ff_mpeg12_frame_rate_tab[frame_rate_index];
145 1923 bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6);
146 1923 avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO;
147 1923 avctx->ticks_per_frame = 1;
148 }
149 1923 break;
150 10216 case EXT_START_CODE:
151
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10216 if (bytes_left >= 1) {
152
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10216 ext_type = (buf[0] >> 4);
153 switch(ext_type) {
154 1784 case 0x1: /* sequence extension */
155
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1784 if (bytes_left >= 6) {
156 1784 horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7);
157 1784 vert_size_ext = (buf[2] >> 5) & 3;
158 1784 bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1);
159 1784 frame_rate_ext_n = (buf[5] >> 5) & 3;
160 1784 frame_rate_ext_d = (buf[5] & 0x1f);
161 1784 pc->progressive_sequence = buf[1] & (1 << 3);
162 1784 avctx->has_b_frames= !(buf[5] >> 7);
163
164
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1784 chroma_format = (buf[1] >> 1) & 3;
165 switch (chroma_format) {
166 747 case 1: pix_fmt = AV_PIX_FMT_YUV420P; break;
167 1037 case 2: pix_fmt = AV_PIX_FMT_YUV422P; break;
168 case 3: pix_fmt = AV_PIX_FMT_YUV444P; break;
169 }
170
171 1784 pc->width = (pc->width & 0xFFF) | (horiz_size_ext << 12);
172 1784 pc->height = (pc->height& 0xFFF) | ( vert_size_ext << 12);
173 1784 bit_rate = (bit_rate&0x3FFFF) | (bit_rate_ext << 18);
174
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1784 if(did_set_size)
175 154 set_dim_ret = ff_set_dimensions(avctx, pc->width, pc->height);
176 1784 avctx->framerate.num = pc->frame_rate.num * (frame_rate_ext_n + 1);
177 1784 avctx->framerate.den = pc->frame_rate.den * (frame_rate_ext_d + 1);
178 1784 avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO;
179 1784 avctx->ticks_per_frame = 2;
180 }
181 1784 break;
182 7804 case 0x8: /* picture coding extension */
183
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7804 if (bytes_left >= 5) {
184 7804 top_field_first = buf[3] & (1 << 7);
185 7804 repeat_first_field = buf[3] & (1 << 1);
186 7804 progressive_frame = buf[4] & (1 << 7);
187
188 /* check if we must repeat the frame */
189 7804 s->repeat_pict = 1;
190
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7804 if (repeat_first_field) {
191
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6 if (pc->progressive_sequence) {
192 if (top_field_first)
193 s->repeat_pict = 5;
194 else
195 s->repeat_pict = 3;
196
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6 } else if (progressive_frame) {
197 6 s->repeat_pict = 2;
198 }
199 }
200
201
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7804 if (!pc->progressive_sequence && !progressive_frame) {
202
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4426 if (top_field_first)
203 598 s->field_order = AV_FIELD_TT;
204 else
205 3828 s->field_order = AV_FIELD_BB;
206 } else
207 3378 s->field_order = AV_FIELD_PROGRESSIVE;
208 }
209 7804 break;
210 }
211 }
212 10216 break;
213 case -1:
214 goto the_end;
215 11572 default:
216 /* we stop parsing when we encounter a slice. It ensures
217 that this function takes a negligible amount of time */
218
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11572 if (start_code >= SLICE_MIN_START_CODE &&
219
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11572 start_code <= SLICE_MAX_START_CODE)
220 8693 goto the_end;
221 2879 break;
222 }
223 }
224 253 the_end:
225
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8946 if (set_dim_ret < 0)
226 av_log(avctx, AV_LOG_ERROR, "Failed to set dimensions\n");
227
228
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8946 if (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO && bit_rate) {
229 1784 avctx->rc_max_rate = 400LL*bit_rate;
230 }
231
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8946 if (bit_rate &&
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1923 ((avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate != 0x3FFFF) || vbv_delay != 0xFFFF)) {
233 1015 avctx->bit_rate = 400LL*bit_rate;
234 }
235
236
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8946 if (pix_fmt != AV_PIX_FMT_NONE) {
237 1923 s->format = pix_fmt;
238 1923 s->width = pc->width;
239 1923 s->height = pc->height;
240 1923 s->coded_width = FFALIGN(pc->width, 16);
241 1923 s->coded_height = FFALIGN(pc->height, 16);
242 }
243
244 #if FF_API_AVCTX_TIMEBASE
245
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8946 if (avctx->framerate.num)
246 8654 avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1}));
247 #endif
248 8946 }
249
250 45538 static int mpegvideo_parse(AVCodecParserContext *s,
251 AVCodecContext *avctx,
252 const uint8_t **poutbuf, int *poutbuf_size,
253 const uint8_t *buf, int buf_size)
254 {
255 45538 struct MpvParseContext *pc1 = s->priv_data;
256 45538 ParseContext *pc= &pc1->pc;
257 int next;
258
259
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45538 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
260 2787 next= buf_size;
261 }else{
262 #if FF_API_FLAG_TRUNCATED
263 42751 next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s);
264 #else
265 next = mpeg1_find_frame_end(pc, buf, buf_size, s);
266 #endif
267
268
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42751 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
269 36592 *poutbuf = NULL;
270 36592 *poutbuf_size = 0;
271 36592 return buf_size;
272 }
273
274 }
275 /* we have a full frame : we just parse the first few MPEG headers
276 to have the full timing information. The time take by this
277 function should be negligible for uncorrupted streams */
278 8946 mpegvideo_extract_headers(s, avctx, buf, buf_size);
279 ff_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n",
280 s->pict_type, av_q2d(avctx->framerate), s->repeat_pict);
281
282 8946 *poutbuf = buf;
283 8946 *poutbuf_size = buf_size;
284 8946 return next;
285 }
286
287 662 static int mpegvideo_parse_init(AVCodecParserContext *s)
288 {
289 662 s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial
290 662 return 0;
291 }
292
293 const AVCodecParser ff_mpegvideo_parser = {
294 .codec_ids = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO },
295 .priv_data_size = sizeof(struct MpvParseContext),
296 .parser_init = mpegvideo_parse_init,
297 .parser_parse = mpegvideo_parse,
298 .parser_close = ff_parse_close,
299 };
300