FFmpeg
decode_video.c
/*
* Copyright (c) 2001 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/**
* @file
* video decoding with libavcodec API example
*
* @example decode_video.c
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define INBUF_SIZE 4096
static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize,
char *filename)
{
FILE *f;
int i;
f = fopen(filename,"w");
fprintf(f, "P5\n%d %d\n%d\n", xsize, ysize, 255);
for (i = 0; i < ysize; i++)
fwrite(buf + i * wrap, 1, xsize, f);
fclose(f);
}
const char *filename)
{
char buf[1024];
int ret;
if (ret < 0) {
fprintf(stderr, "Error sending a packet for decoding\n");
exit(1);
}
while (ret >= 0) {
if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
return;
else if (ret < 0) {
fprintf(stderr, "Error during decoding\n");
exit(1);
}
printf("saving frame %3d\n", dec_ctx->frame_number);
fflush(stdout);
/* the picture is allocated by the decoder. no need to
free it */
snprintf(buf, sizeof(buf), "%s-%d", filename, dec_ctx->frame_number);
frame->width, frame->height, buf);
}
}
int main(int argc, char **argv)
{
const char *filename, *outfilename;
const AVCodec *codec;
AVCodecContext *c= NULL;
FILE *f;
uint8_t *data;
size_t data_size;
int ret;
if (argc <= 2) {
fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
exit(0);
}
filename = argv[1];
outfilename = argv[2];
if (!pkt)
exit(1);
/* set end of buffer to 0 (this ensures that no overreading happens for damaged MPEG streams) */
/* find the MPEG-1 video decoder */
if (!codec) {
fprintf(stderr, "Codec not found\n");
exit(1);
}
parser = av_parser_init(codec->id);
if (!parser) {
fprintf(stderr, "parser not found\n");
exit(1);
}
if (!c) {
fprintf(stderr, "Could not allocate video codec context\n");
exit(1);
}
/* For some codecs, such as msmpeg4 and mpeg4, width and height
MUST be initialized there because this information is not
available in the bitstream. */
/* open it */
if (avcodec_open2(c, codec, NULL) < 0) {
fprintf(stderr, "Could not open codec\n");
exit(1);
}
f = fopen(filename, "rb");
if (!f) {
fprintf(stderr, "Could not open %s\n", filename);
exit(1);
}
if (!frame) {
fprintf(stderr, "Could not allocate video frame\n");
exit(1);
}
while (!feof(f)) {
/* read raw data from the input file */
data_size = fread(inbuf, 1, INBUF_SIZE, f);
if (!data_size)
break;
/* use the parser to split the data into frames */
data = inbuf;
while (data_size > 0) {
ret = av_parser_parse2(parser, c, &pkt->data, &pkt->size,
data, data_size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
if (ret < 0) {
fprintf(stderr, "Error while parsing\n");
exit(1);
}
data += ret;
data_size -= ret;
if (pkt->size)
decode(c, frame, pkt, outfilename);
}
}
/* flush the decoder */
decode(c, frame, NULL, outfilename);
fclose(f);
av_parser_close(parser);
return 0;
}
AVCodec
AVCodec.
Definition: avcodec.h:3482
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:55
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
AVFrame::width
int width
Definition: frame.h:353
AVPacket::data
uint8_t * data
Definition: avcodec.h:1478
pgm_save
static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize, char *filename)
Definition: decode_video.c:38
av_packet_free
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:309
av_parser_init
AVCodecParserContext * av_parser_init(int codec_id)
AVERROR
#define AVERROR(e)
Definition: error.h:43
av_frame_alloc
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
avcodec_alloc_context3
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
avcodec_receive_frame
int avcodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
Return decoded output data from a decoder.
decode
static void decode(AVCodecContext *dec_ctx, AVFrame *frame, AVPacket *pkt, const char *filename)
Definition: decode_video.c:51
avcodec_free_context
void avcodec_free_context(AVCodecContext **avctx)
Free the codec context and everything associated with it and write NULL to the provided pointer.
avcodec_open2
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
AV_CODEC_ID_MPEG1VIDEO
@ AV_CODEC_ID_MPEG1VIDEO
Definition: avcodec.h:219
AVPacket::size
int size
Definition: avcodec.h:1479
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
avcodec_find_decoder
AVCodec * avcodec_find_decoder(enum AVCodecID id)
Find a registered decoder with a matching codec ID.
av_packet_alloc
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
frame
static AVFrame * frame
Definition: demuxing_decoding.c:53
AVCodec::id
enum AVCodecID id
Definition: avcodec.h:3496
avcodec_send_packet
int avcodec_send_packet(AVCodecContext *avctx, const AVPacket *avpkt)
Supply raw packet data as input to a decoder.
avcodec.h
AVCodecParserContext
Definition: avcodec.h:5109
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: avcodec.h:791
AVCodecContext
main external API structure.
Definition: avcodec.h:1566
AVFrame::height
int height
Definition: frame.h:353
pkt
static AVPacket pkt
Definition: demuxing_decoding.c:54
av_parser_parse2
int av_parser_parse2(AVCodecParserContext *s, AVCodecContext *avctx, uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size, int64_t pts, int64_t dts, int64_t pos)
Parse a packet.
AVCodecContext::frame_number
int frame_number
Frame counter, set by libavcodec.
Definition: avcodec.h:2257
AVPacket
This structure stores compressed data.
Definition: avcodec.h:1455
AVFrame::linesize
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:326
main
int main(int argc, char **argv)
Definition: decode_video.c:83
INBUF_SIZE
#define INBUF_SIZE
Definition: decode_video.c:36
dec_ctx
static AVCodecContext * dec_ctx
Definition: filtering_audio.c:43
av_parser_close
void av_parser_close(AVCodecParserContext *s)