1 /*
2 * Copyright (c) 2001 Fabrice Bellard
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a copy
5 * of this software and associated documentation files (the "Software"), to deal
6 * in the Software without restriction, including without limitation the rights
7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 * copies of the Software, and to permit persons to whom the Software is
9 * furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20 * THE SOFTWARE.
21 */
22
23 /**
24 * @file
25 * video decoding with libavcodec API example
26 *
27 * @example decode_video.c
28 */
29
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <string.h>
33
34 #include <libavcodec/avcodec.h>
35
36 #define INBUF_SIZE 4096
37
pgm_save(unsigned char * buf,int wrap,int xsize,int ysize,char * filename)38 static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize,
39 char *filename)
40 {
41 FILE *f;
42 int i;
43
44 f = fopen(filename,"wb");
45 fprintf(f, "P5\n%d %d\n%d\n", xsize, ysize, 255);
46 for (i = 0; i < ysize; i++)
47 fwrite(buf + i * wrap, 1, xsize, f);
48 fclose(f);
49 }
50
decode(AVCodecContext * dec_ctx,AVFrame * frame,AVPacket * pkt,const char * filename)51 static void decode(AVCodecContext *dec_ctx, AVFrame *frame, AVPacket *pkt,
52 const char *filename)
53 {
54 char buf[1024];
55 int ret;
56
57 ret = avcodec_send_packet(dec_ctx, pkt);
58 if (ret < 0) {
59 fprintf(stderr, "Error sending a packet for decoding\n");
60 exit(1);
61 }
62
63 while (ret >= 0) {
64 ret = avcodec_receive_frame(dec_ctx, frame);
65 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
66 return;
67 else if (ret < 0) {
68 fprintf(stderr, "Error during decoding\n");
69 exit(1);
70 }
71
72 printf("saving frame %3d\n", dec_ctx->frame_number);
73 fflush(stdout);
74
75 /* the picture is allocated by the decoder. no need to
76 free it */
77 snprintf(buf, sizeof(buf), "%s-%d", filename, dec_ctx->frame_number);
78 pgm_save(frame->data[0], frame->linesize[0],
79 frame->width, frame->height, buf);
80 }
81 }
82
main(int argc,char ** argv)83 int main(int argc, char **argv)
84 {
85 const char *filename, *outfilename;
86 const AVCodec *codec;
87 AVCodecParserContext *parser;
88 AVCodecContext *c= NULL;
89 FILE *f;
90 AVFrame *frame;
91 uint8_t inbuf[INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
92 uint8_t *data;
93 size_t data_size;
94 int ret;
95 int eof;
96 AVPacket *pkt;
97
98 if (argc <= 2) {
99 fprintf(stderr, "Usage: %s <input file> <output file>\n"
100 "And check your input file is encoded by mpeg1video please.\n", argv[0]);
101 exit(0);
102 }
103 filename = argv[1];
104 outfilename = argv[2];
105
106 pkt = av_packet_alloc();
107 if (!pkt)
108 exit(1);
109
110 /* set end of buffer to 0 (this ensures that no overreading happens for damaged MPEG streams) */
111 memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
112
113 /* find the MPEG-1 video decoder */
114 codec = avcodec_find_decoder(AV_CODEC_ID_MPEG1VIDEO);
115 if (!codec) {
116 fprintf(stderr, "Codec not found\n");
117 exit(1);
118 }
119
120 parser = av_parser_init(codec->id);
121 if (!parser) {
122 fprintf(stderr, "parser not found\n");
123 exit(1);
124 }
125
126 c = avcodec_alloc_context3(codec);
127 if (!c) {
128 fprintf(stderr, "Could not allocate video codec context\n");
129 exit(1);
130 }
131
132 /* For some codecs, such as msmpeg4 and mpeg4, width and height
133 MUST be initialized there because this information is not
134 available in the bitstream. */
135
136 /* open it */
137 if (avcodec_open2(c, codec, NULL) < 0) {
138 fprintf(stderr, "Could not open codec\n");
139 exit(1);
140 }
141
142 f = fopen(filename, "rb");
143 if (!f) {
144 fprintf(stderr, "Could not open %s\n", filename);
145 exit(1);
146 }
147
148 frame = av_frame_alloc();
149 if (!frame) {
150 fprintf(stderr, "Could not allocate video frame\n");
151 exit(1);
152 }
153
154 do {
155 /* read raw data from the input file */
156 data_size = fread(inbuf, 1, INBUF_SIZE, f);
157 if (ferror(f))
158 break;
159 eof = !data_size;
160
161 /* use the parser to split the data into frames */
162 data = inbuf;
163 while (data_size > 0 || eof) {
164 ret = av_parser_parse2(parser, c, &pkt->data, &pkt->size,
165 data, data_size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
166 if (ret < 0) {
167 fprintf(stderr, "Error while parsing\n");
168 exit(1);
169 }
170 data += ret;
171 data_size -= ret;
172
173 if (pkt->size)
174 decode(c, frame, pkt, outfilename);
175 else if (eof)
176 break;
177 }
178 } while (!eof);
179
180 /* flush the decoder */
181 decode(c, frame, NULL, outfilename);
182
183 fclose(f);
184
185 av_parser_close(parser);
186 avcodec_free_context(&c);
187 av_frame_free(&frame);
188 av_packet_free(&pkt);
189
190 return 0;
191 }
192