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extern "C" {
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
}
char const video[] = "/home/carl/Films/A town called panic.divx";//Ghostbusters.avi";
static void
save_frame (AVFrame *frame, int width, int height, int N)
{
char filename[32];
sprintf (filename, "frame%d.ppm", N);
FILE* file = fopen (filename, "wb");
if (file == NULL) {
return;
}
fprintf (file, "P6\n%d %d\n255\n", width, height);
for (int y = 0; y < height; y++) {
fwrite (frame->data[0] + y * frame->linesize[0], 1, width * 3, file);
}
fclose (file);
}
int
main (int argc, char* argv[])
{
av_register_all ();
AVFormatContext* format_context = NULL;
if (avformat_open_input (&format_context, video, NULL, NULL) != 0) {
fprintf (stderr, "avformat_open_input failed.\n");
return -1;
}
if (avformat_find_stream_info (format_context, NULL) < 0) {
fprintf (stderr, "av_find_stream_info failed.\n");
return -1;
}
av_dump_format (format_context, 0, video, 0);
int video_stream = -1;
for (uint32_t i = 0; i < format_context->nb_streams; ++i) {
if (format_context->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
video_stream = i;
break;
}
}
AVCodecContext* codec_context = format_context->streams[video_stream]->codec;
AVCodec* codec = avcodec_find_decoder (codec_context->codec_id);
if (codec == NULL) {
fprintf (stderr, "avcodec_find_decoder failed.\n");
return -1;
}
if (avcodec_open2 (codec_context, codec, NULL) < 0) {
fprintf (stderr, "avcodec_open failed.\n");
return -1;
}
if (codec_context->time_base.num > 1000 && codec_context->time_base.den == 1) {
codec_context->time_base.den = 1000;
}
AVFrame* frame = avcodec_alloc_frame ();
AVFrame* frame_RGB = avcodec_alloc_frame ();
if (frame_RGB == NULL) {
fprintf (stderr, "avcodec_alloc_frame failed.\n");
return -1;
}
int num_bytes = avpicture_get_size (PIX_FMT_RGB24, codec_context->width, codec_context->height);
uint8_t* buffer = (uint8_t *) malloc (num_bytes);
avpicture_fill ((AVPicture *) frame_RGB, buffer, PIX_FMT_RGB24, codec_context->width, codec_context->height);
int i = 0;
AVPacket packet;
while (av_read_frame (format_context, &packet) >= 0) {
int frame_finished;
if (packet.stream_index == video_stream) {
avcodec_decode_video2 (codec_context, frame, &frame_finished, &packet);
if (frame_finished) {
static struct SwsContext *img_convert_context;
if (img_convert_context == NULL) {
int w = codec_context->width;
int h = codec_context->height;
img_convert_context = sws_getContext (
w, h,
codec_context->pix_fmt,
w, h, PIX_FMT_RGB24, SWS_BICUBIC,
NULL, NULL, NULL
);
if (img_convert_context == NULL) {
fprintf (stderr, "sws_getContext failed.\n");
return -1;
}
}
sws_scale (
img_convert_context, frame->data, frame->linesize, 0,
codec_context->height, frame_RGB->data, frame_RGB->linesize
);
++i;
if (i > 100 && i < 150) {
save_frame (frame_RGB, codec_context->width, codec_context->height, i);
}
}
}
av_free_packet (&packet);
}
free (buffer);
av_free (frame_RGB);
av_free (frame);
avcodec_close(codec_context);
avformat_close_input (&format_context);
return 0;
}
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