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,"w");
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 AVPacket *pkt;
96
97 if (argc <= 2) {
98 fprintf(stderr, "Usage: %s <input file> <output file>\n"
99 "And check your input file is encoded by mpeg1video please.\n", argv[0]);
100 exit(0);
101 }
102 filename = argv[1];
103 outfilename = argv[2];
104
105 pkt = av_packet_alloc();
106 if (!pkt)
107 exit(1);
108
109 /* set end of buffer to 0 (this ensures that no overreading happens for damaged MPEG streams) */
110 memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
111
112 /* find the MPEG-1 video decoder */
113 codec = avcodec_find_decoder(AV_CODEC_ID_MPEG1VIDEO);
114 if (!codec) {
115 fprintf(stderr, "Codec not found\n");
116 exit(1);
117 }
118
119 parser = av_parser_init(codec->id);
120 if (!parser) {
121 fprintf(stderr, "parser not found\n");
122 exit(1);
123 }
124
125 c = avcodec_alloc_context3(codec);
126 if (!c) {
127 fprintf(stderr, "Could not allocate video codec context\n");
128 exit(1);
129 }
130
131 /* For some codecs, such as msmpeg4 and mpeg4, width and height
132 MUST be initialized there because this information is not
133 available in the bitstream. */
134
135 /* open it */
136 if (avcodec_open2(c, codec, NULL) < 0) {
137 fprintf(stderr, "Could not open codec\n");
138 exit(1);
139 }
140
141 f = fopen(filename, "rb");
142 if (!f) {
143 fprintf(stderr, "Could not open %s\n", filename);
144 exit(1);
145 }
146
147 frame = av_frame_alloc();
148 if (!frame) {
149 fprintf(stderr, "Could not allocate video frame\n");
150 exit(1);
151 }
152
153 while (!feof(f)) {
154 /* read raw data from the input file */
155 data_size = fread(inbuf, 1, INBUF_SIZE, f);
156 if (!data_size)
157 break;
158
159 /* use the parser to split the data into frames */
160 data = inbuf;
161 while (data_size > 0) {
162 ret = av_parser_parse2(parser, c, &pkt->data, &pkt->size,
163 data, data_size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
164 if (ret < 0) {
165 fprintf(stderr, "Error while parsing\n");
166 exit(1);
167 }
168 data += ret;
169 data_size -= ret;
170
171 if (pkt->size)
172 decode(c, frame, pkt, outfilename);
173 }
174 }
175
176 /* flush the decoder */
177 decode(c, frame, NULL, outfilename);
178
179 fclose(f);
180
181 av_parser_close(parser);
182 avcodec_free_context(&c);
183 av_frame_free(&frame);
184 av_packet_free(&pkt);
185
186 return 0;
187 }
188