Get duration, width and height of a video using ffmpeg

get_duration.c

#include <stdio.h>
#include <assert.h>

#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>

void openVideoFile(char *filename) {
    AVFormatContext* pFormatCtx;
    AVCodecContext* pCodecCtx;
    int videoStream = -1;
    int i = 0;

	// open video file
    int ret = avformat_open_input(&pFormatCtx, filename, NULL, NULL);
    if (ret != 0) {
        printf("Unable to open video file: %s\n", filename);
        return;
    }

    // Retrieve stream information
    ret = avformat_find_stream_info(pFormatCtx, NULL);
    assert(ret >= 0);

    printf("\n");
    printf("Duration: %lus\n", pFormatCtx->duration/1000000);
}

int main(int argc, char **argv) {

	if(argc != 2) {
		printf("Usage: %s <path-to-video>\n", argv[0]);
		exit(1);
	}

	// register all formats and codecs
    av_register_all();

    openVideoFile(argv[1]);
}

get_width_and_height.c

#include <stdio.h>
#include <assert.h>

#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>

void openVideoFile(char *filename) {
	AVFormatContext* pFormatCtx;
	AVCodecContext* pCodecCtx;
	int videoStream = -1;
    int i = 0;

	// open video file
    int ret = avformat_open_input(&pFormatCtx, filename, NULL, NULL);
    if (ret != 0) {
        printf("Unable to open video file: %s\n", filename);
        return;
    }

    // Retrieve stream information
    ret = avformat_find_stream_info(pFormatCtx, NULL);
    assert(ret >= 0);

    for(i = 0; i < pFormatCtx->nb_streams; i++) {
        if (pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO && videoStream < 0) {
            videoStream = i;            
        }
    } // end for i
    assert(videoStream != -1);

    // Get a pointer to the codec context for the video stream
    pCodecCtx=pFormatCtx->streams[videoStream]->codec;
    assert(pCodecCtx != NULL);

    printf("\n");
    printf("Width: %d\n", pCodecCtx->width);
    printf("Height: %d\n", pCodecCtx->height);
}

int main(int argc, char **argv) {

	if(argc != 2) {
		printf("Usage: %s <path-to-video>\n", argv[0]);
		exit(1);
	}

	// register all formats and codecs
    av_register_all();

    openVideoFile(argv[1]);
}

Makefile

CC = gcc
LD_FLAGS = -lavformat -lavcodec

all: get_width_and_height

get_width_and_height: get_width_and_height.c
	$(CC) -o $@ $< $(LD_FLAGS)

clean:
	rm get_width_and_height

it doesn't work for rtp video streams