FFmpeg 4.4.5
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encode_video.c
Go to the documentation of this file.
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 encoding with libavcodec API example
26 *
27 * @example encode_video.c
28 */
29
30#include <stdio.h>
31#include <stdlib.h>
32#include <string.h>
33
34#include <libavcodec/avcodec.h>
35
36#include <libavutil/opt.h>
37#include <libavutil/imgutils.h>
38
39static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
40 FILE *outfile)
41{
42 int ret;
43
44 /* send the frame to the encoder */
45 if (frame)
46 printf("Send frame %3"PRId64"\n", frame->pts);
47
48 ret = avcodec_send_frame(enc_ctx, frame);
49 if (ret < 0) {
50 fprintf(stderr, "Error sending a frame for encoding\n");
51 exit(1);
52 }
53
54 while (ret >= 0) {
55 ret = avcodec_receive_packet(enc_ctx, pkt);
56 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
57 return;
58 else if (ret < 0) {
59 fprintf(stderr, "Error during encoding\n");
60 exit(1);
61 }
62
63 printf("Write packet %3"PRId64" (size=%5d)\n", pkt->pts, pkt->size);
64 fwrite(pkt->data, 1, pkt->size, outfile);
66 }
67}
68
69int main(int argc, char **argv)
70{
71 const char *filename, *codec_name;
72 const AVCodec *codec;
73 AVCodecContext *c= NULL;
74 int i, ret, x, y;
75 FILE *f;
78 uint8_t endcode[] = { 0, 0, 1, 0xb7 };
79
80 if (argc <= 2) {
81 fprintf(stderr, "Usage: %s <output file> <codec name>\n", argv[0]);
82 exit(0);
83 }
84 filename = argv[1];
85 codec_name = argv[2];
86
87 /* find the mpeg1video encoder */
88 codec = avcodec_find_encoder_by_name(codec_name);
89 if (!codec) {
90 fprintf(stderr, "Codec '%s' not found\n", codec_name);
91 exit(1);
92 }
93
94 c = avcodec_alloc_context3(codec);
95 if (!c) {
96 fprintf(stderr, "Could not allocate video codec context\n");
97 exit(1);
98 }
99
101 if (!pkt)
102 exit(1);
103
104 /* put sample parameters */
105 c->bit_rate = 400000;
106 /* resolution must be a multiple of two */
107 c->width = 352;
108 c->height = 288;
109 /* frames per second */
110 c->time_base = (AVRational){1, 25};
111 c->framerate = (AVRational){25, 1};
112
113 /* emit one intra frame every ten frames
114 * check frame pict_type before passing frame
115 * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
116 * then gop_size is ignored and the output of encoder
117 * will always be I frame irrespective to gop_size
118 */
119 c->gop_size = 10;
120 c->max_b_frames = 1;
122
123 if (codec->id == AV_CODEC_ID_H264)
124 av_opt_set(c->priv_data, "preset", "slow", 0);
125
126 /* open it */
127 ret = avcodec_open2(c, codec, NULL);
128 if (ret < 0) {
129 fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
130 exit(1);
131 }
132
133 f = fopen(filename, "wb");
134 if (!f) {
135 fprintf(stderr, "Could not open %s\n", filename);
136 exit(1);
137 }
138
140 if (!frame) {
141 fprintf(stderr, "Could not allocate video frame\n");
142 exit(1);
143 }
144 frame->format = c->pix_fmt;
145 frame->width = c->width;
146 frame->height = c->height;
147
148 ret = av_frame_get_buffer(frame, 0);
149 if (ret < 0) {
150 fprintf(stderr, "Could not allocate the video frame data\n");
151 exit(1);
152 }
153
154 /* encode 1 second of video */
155 for (i = 0; i < 25; i++) {
156 fflush(stdout);
157
158 /* make sure the frame data is writable */
160 if (ret < 0)
161 exit(1);
162
163 /* prepare a dummy image */
164 /* Y */
165 for (y = 0; y < c->height; y++) {
166 for (x = 0; x < c->width; x++) {
167 frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
168 }
169 }
170
171 /* Cb and Cr */
172 for (y = 0; y < c->height/2; y++) {
173 for (x = 0; x < c->width/2; x++) {
174 frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
175 frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
176 }
177 }
178
179 frame->pts = i;
180
181 /* encode the image */
182 encode(c, frame, pkt, f);
183 }
184
185 /* flush the encoder */
186 encode(c, NULL, pkt, f);
187
188 /* add sequence end code to have a real MPEG file */
189 if (codec->id == AV_CODEC_ID_MPEG1VIDEO || codec->id == AV_CODEC_ID_MPEG2VIDEO)
190 fwrite(endcode, 1, sizeof(endcode), f);
191 fclose(f);
192
196
197 return 0;
198}
Libavcodec external API header.
int main(int argc, char *argv[])
static AVPacket * pkt
static AVFrame * frame
static void encode(AVCodecContext *ctx, AVFrame *frame, AVPacket *pkt, FILE *output)
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
AVCodec * avcodec_find_encoder_by_name(const char *name)
Find a registered encoder with the specified name.
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
void avcodec_free_context(AVCodecContext **avctx)
Free the codec context and everything associated with it and write NULL to the provided pointer.
@ AV_CODEC_ID_H264
Definition codec_id.h:76
@ AV_CODEC_ID_MPEG1VIDEO
Definition codec_id.h:50
@ AV_CODEC_ID_MPEG2VIDEO
preferred ID for MPEG-1/2 video decoding
Definition codec_id.h:51
int avcodec_receive_packet(AVCodecContext *avctx, AVPacket *avpkt)
Read encoded data from the encoder.
int avcodec_send_frame(AVCodecContext *avctx, const AVFrame *frame)
Supply a raw video or audio frame to the encoder.
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
#define AVERROR_EOF
End of file.
Definition error.h:55
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition error.h:119
#define AVERROR(e)
Definition error.h:43
int av_frame_get_buffer(AVFrame *frame, int align)
Allocate new buffer(s) for audio or video data.
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
int av_frame_make_writable(AVFrame *frame)
Ensure that the frame data is writable, avoiding data copy if possible.
int av_opt_set(void *obj, const char *name, const char *val, int search_flags)
misc image utilities
AVOptions.
@ AV_PIX_FMT_YUV420P
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition pixfmt.h:66
main external API structure.
Definition avcodec.h:536
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition avcodec.h:746
int width
picture width / height.
Definition avcodec.h:709
int max_b_frames
maximum number of B-frames between non-B-frames Note: The output will be delayed by max_b_frames+1 re...
Definition avcodec.h:796
AVRational framerate
Definition avcodec.h:2071
int64_t bit_rate
the average bitrate
Definition avcodec.h:586
int gop_size
the number of pictures in a group of pictures, or 0 for intra_only
Definition avcodec.h:731
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented.
Definition avcodec.h:659
void * priv_data
Definition avcodec.h:563
AVCodec.
Definition codec.h:197
enum AVCodecID id
Definition codec.h:211
This structure describes decoded (raw) audio or video data.
Definition frame.h:318
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition frame.h:411
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition frame.h:332
int width
Definition frame.h:376
int height
Definition frame.h:376
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition frame.h:349
int format
format of the frame, -1 if unknown or unset Values correspond to enum AVPixelFormat for video frames,...
Definition frame.h:391
This structure stores compressed data.
Definition packet.h:346
int size
Definition packet.h:370
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition packet.h:362
uint8_t * data
Definition packet.h:369
Rational number (pair of numerator and denominator).
Definition rational.h:58