FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/mpegvideo_parser.c
Date: 2022-07-05 19:52:29
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 "internal.h"
24 #include "parser.h"
25 #include "mpeg12.h"
26 #include "mpeg12data.h"
27 #include "startcode.h"
28
29 struct MpvParseContext {
30 ParseContext pc;
31 AVRational frame_rate;
32 int progressive_sequence;
33 int width, height;
34 };
35
36 #if !FF_API_FLAG_TRUNCATED
37 /**
38 * Find the end of the current frame in the bitstream.
39 * @return the position of the first byte of the next frame, or -1
40 */
41 static int mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf,
42 int buf_size, AVCodecParserContext *s)
43 {
44 int i;
45 uint32_t state = pc->state;
46
47 /* EOF considered as end of frame */
48 if (buf_size == 0)
49 return 0;
50
51 /*
52 0 frame start -> 1/4
53 1 first_SEQEXT -> 0/2
54 2 first field start -> 3/0
55 3 second_SEQEXT -> 2/0
56 4 searching end
57 */
58
59 for (i = 0; i < buf_size; i++) {
60 av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4);
61 if (pc->frame_start_found & 1) {
62 if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80)
63 pc->frame_start_found--;
64 else if (state == EXT_START_CODE + 2) {
65 if ((buf[i] & 3) == 3)
66 pc->frame_start_found = 0;
67 else
68 pc->frame_start_found = (pc->frame_start_found + 1) & 3;
69 }
70 state++;
71 } else {
72 i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1;
73 if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) {
74 i++;
75 pc->frame_start_found = 4;
76 }
77 if (state == SEQ_END_CODE) {
78 pc->frame_start_found = 0;
79 pc->state = -1;
80 return i + 1;
81 }
82 if (pc->frame_start_found == 2 && state == SEQ_START_CODE)
83 pc->frame_start_found = 0;
84 if (pc->frame_start_found < 4 && state == EXT_START_CODE)
85 pc->frame_start_found++;
86 if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) {
87 if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) {
88 pc->frame_start_found = 0;
89 pc->state = -1;
90 return i - 3;
91 }
92 }
93 if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) {
94 ff_fetch_timestamp(s, i - 3, 1, i > 3);
95 }
96 }
97 }
98 pc->state = state;
99 return END_NOT_FOUND;
100 }
101 #endif
102
103 9085 static void mpegvideo_extract_headers(AVCodecParserContext *s,
104 AVCodecContext *avctx,
105 const uint8_t *buf, int buf_size)
106 {
107 9085 struct MpvParseContext *pc = s->priv_data;
108 9085 const uint8_t *buf_end = buf + buf_size;
109 uint32_t start_code;
110 int frame_rate_index, ext_type, bytes_left;
111 int frame_rate_ext_n, frame_rate_ext_d;
112 int top_field_first, repeat_first_field, progressive_frame;
113 int horiz_size_ext, vert_size_ext, bit_rate_ext;
114 9085 int did_set_size=0;
115 9085 int set_dim_ret = 0;
116 9085 int bit_rate = 0;
117 9085 int vbv_delay = 0;
118 int chroma_format;
119 9085 enum AVPixelFormat pix_fmt = AV_PIX_FMT_NONE;
120 //FIXME replace the crap with get_bits()
121 9085 s->repeat_pict = 0;
122
123
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33230 while (buf < buf_end) {
124 32975 start_code= -1;
125 32975 buf= avpriv_find_start_code(buf, buf_end, &start_code);
126 32975 bytes_left = buf_end - buf;
127
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32975 switch(start_code) {
128 8813 case PICTURE_START_CODE:
129
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8813 if (bytes_left >= 2) {
130 8813 s->pict_type = (buf[1] >> 3) & 7;
131
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8813 if (bytes_left >= 4)
132 8813 vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3] >> 3);
133 }
134 8813 break;
135 1933 case SEQ_START_CODE:
136
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1933 if (bytes_left >= 7) {
137 1933 pc->width = (buf[0] << 4) | (buf[1] >> 4);
138 1933 pc->height = ((buf[1] & 0x0f) << 8) | buf[2];
139
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1933 if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){
140 169 set_dim_ret = ff_set_dimensions(avctx, pc->width, pc->height);
141 169 did_set_size=1;
142 }
143 1933 pix_fmt = AV_PIX_FMT_YUV420P;
144 1933 frame_rate_index = buf[3] & 0xf;
145 1933 pc->frame_rate = avctx->framerate = ff_mpeg12_frame_rate_tab[frame_rate_index];
146 1933 bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6);
147 1933 avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO;
148 1933 avctx->ticks_per_frame = 1;
149 }
150 1933 break;
151 10373 case EXT_START_CODE:
152
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10373 if (bytes_left >= 1) {
153
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10373 ext_type = (buf[0] >> 4);
154 switch(ext_type) {
155 1794 case 0x1: /* sequence extension */
156
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1794 if (bytes_left >= 6) {
157 1794 horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7);
158 1794 vert_size_ext = (buf[2] >> 5) & 3;
159 1794 bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1);
160 1794 frame_rate_ext_n = (buf[5] >> 5) & 3;
161 1794 frame_rate_ext_d = (buf[5] & 0x1f);
162 1794 pc->progressive_sequence = buf[1] & (1 << 3);
163 1794 avctx->has_b_frames= !(buf[5] >> 7);
164
165
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1794 chroma_format = (buf[1] >> 1) & 3;
166 switch (chroma_format) {
167 757 case 1: pix_fmt = AV_PIX_FMT_YUV420P; break;
168 1037 case 2: pix_fmt = AV_PIX_FMT_YUV422P; break;
169 case 3: pix_fmt = AV_PIX_FMT_YUV444P; break;
170 }
171
172 1794 pc->width = (pc->width & 0xFFF) | (horiz_size_ext << 12);
173 1794 pc->height = (pc->height& 0xFFF) | ( vert_size_ext << 12);
174 1794 bit_rate = (bit_rate&0x3FFFF) | (bit_rate_ext << 18);
175
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1794 if(did_set_size)
176 155 set_dim_ret = ff_set_dimensions(avctx, pc->width, pc->height);
177 1794 avctx->framerate.num = pc->frame_rate.num * (frame_rate_ext_n + 1);
178 1794 avctx->framerate.den = pc->frame_rate.den * (frame_rate_ext_d + 1);
179 1794 avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO;
180 1794 avctx->ticks_per_frame = 2;
181 }
182 1794 break;
183 7941 case 0x8: /* picture coding extension */
184
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7941 if (bytes_left >= 5) {
185 7941 top_field_first = buf[3] & (1 << 7);
186 7941 repeat_first_field = buf[3] & (1 << 1);
187 7941 progressive_frame = buf[4] & (1 << 7);
188
189 /* check if we must repeat the frame */
190 7941 s->repeat_pict = 1;
191
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7941 if (repeat_first_field) {
192
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6 if (pc->progressive_sequence) {
193 if (top_field_first)
194 s->repeat_pict = 5;
195 else
196 s->repeat_pict = 3;
197
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6 } else if (progressive_frame) {
198 6 s->repeat_pict = 2;
199 }
200 }
201
202
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7941 if (!pc->progressive_sequence && !progressive_frame) {
203
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4563 if (top_field_first)
204 735 s->field_order = AV_FIELD_TT;
205 else
206 3828 s->field_order = AV_FIELD_BB;
207 } else
208 3378 s->field_order = AV_FIELD_PROGRESSIVE;
209 }
210 7941 break;
211 }
212 }
213 10373 break;
214 case -1:
215 goto the_end;
216 11856 default:
217 /* we stop parsing when we encounter a slice. It ensures
218 that this function takes a negligible amount of time */
219
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11856 if (start_code >= SLICE_MIN_START_CODE &&
220
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11856 start_code <= SLICE_MAX_START_CODE)
221 8830 goto the_end;
222 3026 break;
223 }
224 }
225 255 the_end:
226
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9085 if (set_dim_ret < 0)
227 av_log(avctx, AV_LOG_ERROR, "Failed to set dimensions\n");
228
229
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9085 if (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO && bit_rate) {
230 1794 avctx->rc_max_rate = 400LL*bit_rate;
231 }
232
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9085 if (bit_rate &&
233
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1933 ((avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate != 0x3FFFF) || vbv_delay != 0xFFFF)) {
234 1015 avctx->bit_rate = 400LL*bit_rate;
235 }
236
237
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9085 if (pix_fmt != AV_PIX_FMT_NONE) {
238 1933 s->format = pix_fmt;
239 1933 s->width = pc->width;
240 1933 s->height = pc->height;
241 1933 s->coded_width = FFALIGN(pc->width, 16);
242 1933 s->coded_height = FFALIGN(pc->height, 16);
243 }
244
245 #if FF_API_AVCTX_TIMEBASE
246
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9085 if (avctx->framerate.num)
247 8792 avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1}));
248 #endif
249 9085 }
250
251 47221 static int mpegvideo_parse(AVCodecParserContext *s,
252 AVCodecContext *avctx,
253 const uint8_t **poutbuf, int *poutbuf_size,
254 const uint8_t *buf, int buf_size)
255 {
256 47221 struct MpvParseContext *pc1 = s->priv_data;
257 47221 ParseContext *pc= &pc1->pc;
258 int next;
259
260
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47221 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
261 2787 next= buf_size;
262 }else{
263 #if FF_API_FLAG_TRUNCATED
264 44434 next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s);
265 #else
266 next = mpeg1_find_frame_end(pc, buf, buf_size, s);
267 #endif
268
269
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44434 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
270 38136 *poutbuf = NULL;
271 38136 *poutbuf_size = 0;
272 38136 return buf_size;
273 }
274
275 }
276 /* we have a full frame : we just parse the first few MPEG headers
277 to have the full timing information. The time take by this
278 function should be negligible for uncorrupted streams */
279 9085 mpegvideo_extract_headers(s, avctx, buf, buf_size);
280 ff_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n",
281 s->pict_type, av_q2d(avctx->framerate), s->repeat_pict);
282
283 9085 *poutbuf = buf;
284 9085 *poutbuf_size = buf_size;
285 9085 return next;
286 }
287
288 664 static int mpegvideo_parse_init(AVCodecParserContext *s)
289 {
290 664 s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial
291 664 return 0;
292 }
293
294 const AVCodecParser ff_mpegvideo_parser = {
295 .codec_ids = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO },
296 .priv_data_size = sizeof(struct MpvParseContext),
297 .parser_init = mpegvideo_parse_init,
298 .parser_parse = mpegvideo_parse,
299 .parser_close = ff_parse_close,
300 };
301