FFmpeg
encode_video.c
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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 
39 static 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);
65  av_packet_unref(pkt);
66  }
67 }
68 
69 int main(int argc, char **argv)
70 {
71  const char *filename, *codec_name;
72  const AVCodec *codec;
74  int i, ret, x, y;
75  FILE *f;
76  AVFrame *frame;
77  AVPacket *pkt;
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 
100  pkt = av_packet_alloc();
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 
139  frame = av_frame_alloc();
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, 32);
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 */
159  ret = av_frame_make_writable(frame);
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  fwrite(endcode, 1, sizeof(endcode), f);
190  fclose(f);
191 
193  av_frame_free(&frame);
194  av_packet_free(&pkt);
195 
196  return 0;
197 }
#define NULL
Definition: coverity.c:32
AVRational framerate
Definition: avcodec.h:3101
This structure describes decoded (raw) audio or video data.
Definition: frame.h:268
misc image utilities
int64_t bit_rate
the average bitrate
Definition: avcodec.h:1615
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:1825
int avcodec_receive_packet(AVCodecContext *avctx, AVPacket *avpkt)
Read encoded data from the encoder.
Definition: encode.c:417
int size
Definition: avcodec.h:1478
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1775
static AVPacket pkt
AVCodec.
Definition: avcodec.h:3477
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avcodec.h:1688
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
Definition: avpacket.c:62
uint8_t
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:189
AVOptions.
#define f(width, name)
Definition: cbs_vp9.c:255
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:361
uint8_t * data
Definition: avcodec.h:1477
#define AVERROR_EOF
End of file.
Definition: error.h:55
AVCodec * avcodec_find_encoder_by_name(const char *name)
Find a registered encoder with the specified name.
Definition: allcodecs.c:913
enum AVCodecID id
Definition: avcodec.h:3491
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:260
int width
Definition: frame.h:326
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:202
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
Definition: options.c:156
int width
picture width / height.
Definition: avcodec.h:1738
int main(int argc, char **argv)
Definition: encode_video.c:69
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
int format
format of the frame, -1 if unknown or unset Values correspond to enum AVPixelFormat for video frames...
Definition: frame.h:341
Libavcodec external API header.
void avcodec_free_context(AVCodecContext **avctx)
Free the codec context and everything associated with it and write NULL to the provided pointer...
Definition: options.c:171
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:299
main external API structure.
Definition: avcodec.h:1565
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:599
int avcodec_send_frame(AVCodecContext *avctx, const AVFrame *frame)
Supply a raw video or audio frame to the encoder.
Definition: encode.c:387
Rational number (pair of numerator and denominator).
Definition: rational.h:58
static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt, FILE *outfile)
Definition: encode_video.c:39
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
Definition: utils.c:542
int av_frame_get_buffer(AVFrame *frame, int align)
Allocate new buffer(s) for audio or video data.
Definition: frame.c:324
int av_frame_make_writable(AVFrame *frame)
Ensure that the frame data is writable, avoiding data copy if possible.
Definition: frame.c:611
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:282
int gop_size
the number of pictures in a group of pictures, or 0 for intra_only
Definition: avcodec.h:1760
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:66
void * priv_data
Definition: avcodec.h:1592
printf("static const uint8_t my_array[100] = {\n")
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
Definition: avpacket.c:51
int height
Definition: frame.h:326
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
This structure stores compressed data.
Definition: avcodec.h:1454
int av_opt_set(void *obj, const char *name, const char *val, int search_flags)
Definition: opt.c:449
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: avcodec.h:1470
FILE * outfile
Definition: audiogen.c:96