Open mp4 with libVLC and OpenCV C++

asked 2015-02-24 01:03:16 -0600

seidju gravatar image

I want to play video file, that i obtained from IP-camera (H264-codec) using libVLC and OpenCV, so i took the code from this post, then created project in VS 2010, and put my mp4 file into project folder ("5.mp4"). When i started it - i got this errors:

main error: open of `5.mp4' failed

main error: Your input can't be opened

main error: VLC is unable to open the MRL '5.mp4'. Check the log for details.

Here's my code:

#include <vlc/vlc.h>
#include <opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <stdio.h>

using namespace cv; 
using namespace std;

struct VideoDataStruct {
  int param;

int done = 0;
libvlc_media_player_t *mp;
unsigned int videoBufferSize = 0;
uint8_t *videoBuffer = 0;

 void cbVideoPrerender(void *p_video_data, uint8_t **pp_pixel_buffer, int size) {
// Locking
  if (size > videoBufferSize || !videoBuffer)
    printf("Reallocate raw video buffer\n");
    videoBuffer = (uint8_t *) malloc(size);
    videoBufferSize = size;

   *pp_pixel_buffer = videoBuffer;

 void cbVideoPostrender(void *p_video_data, uint8_t *p_pixel_buffer, int width, int height, int pixel_pitch, int size, int64_t pts) {
     // Unlocking

 static void handleEvent(const libvlc_event_t* pEvt, void* pUserData) {
   libvlc_time_t time;
      case libvlc_MediaPlayerTimeChanged:
          time = libvlc_media_player_get_time(mp);
          printf("MediaPlayerTimeChanged %lld ms\n", (long long)time);
      case libvlc_MediaPlayerEndReached:
          printf ("MediaPlayerEndReached\n");
          done = 1;
          printf("%s\n", libvlc_event_type_name(pEvt->type));

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

// VLC pointers 
libvlc_instance_t *inst;
libvlc_media_t *m;
void *pUserData = 0;
VideoDataStruct dataStruct;

// VLC options
char smem_options[1000];
// RV24
    , "#transcode{vcodec=RV24}:smem{"
    , (long long int)(intptr_t)(void*)&cbVideoPrerender
    , (long long int)(intptr_t)(void*)&cbVideoPostrender
    , (long long int)(intptr_t)(void*)&dataStruct

const char * const vlc_args[] = {
          "-I", "dummy",            // Don't use any interface
          "--ignore-config",        // Don't use VLC's config
          "--extraintf=logger",     // Log anything
          "--verbose=1",            // Be verbose
          "--sout", smem_options    // Stream to memory

// We launch VLC
inst = libvlc_new(sizeof(vlc_args) / sizeof(vlc_args[0]), vlc_args);

/* Create a new item */
m = libvlc_media_new_location(inst, "5.mp4");

/* Create a media player playing environement */
mp = libvlc_media_player_new_from_media (m);

libvlc_event_manager_t* eventManager = libvlc_media_player_event_manager(mp);
libvlc_event_attach(eventManager, libvlc_MediaPlayerTimeChanged, handleEvent, pUserData);
libvlc_event_attach(eventManager, libvlc_MediaPlayerEndReached, handleEvent, pUserData);
libvlc_event_attach(eventManager, libvlc_MediaPlayerPositionChanged, handleEvent, pUserData);

libvlc_video_set_format(mp, "RV24", 1280, 720, 1280* 3 );

/* play the media_player */
libvlc_media_player_play (mp);

     if(videoBuffer)            // Check for invalid input
         // CV_8UC3 = 8 bits, 3 chanels
         Mat img = Mat(Size(1280, 720), CV_8UC3, videoBuffer);
         // cvtColor(img, img, CV_RGB2BGR);
         namedWindow("Display window", WINDOW_AUTOSIZE);    // Create a window for display.
         imshow("Display window", img);     // Show our image inside it.
 libvlc_release (inst);

I guess, that is easy to fix, but i could't find any information at the Internet. I also tryied to put it into "C:\5.mp4", but i got the same errors. Thanks for any help.

EDIT: Ok, so i fixed this issue, i need to put file:/// before "5.mp4", now my video is playing, but it looks like this: enter image description here

EDIT02 Ok, with "*.avi" everything looks good, so i guess problem with this file - i recorded it frop IP-camera, using VLC, and saved it into *.mp4

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Thank you very much. I was seeking for such code for several months and now your code really works! LibVLC+OpenCV

H. Khosravi gravatar imageH. Khosravi ( 2015-02-24 05:07:22 -0600 )edit

@seidju: Hi! I am trying to achieve nearly the same thing (RTSP stream to OpenCV mat via LibSVM), but I have run into an issue. I have added your code to my own, but when I try to connect to the IP camera I get the following error in the vlc_log file:

-- logger module started -- stream_out_transcode error: cannot find video encoder (module:any fourcc:R24 ). Take a look few lines earlier to see possible reason. stream_out_transcode error: cannot create video chain core error: cannot create packetizer output (h264) core error: ES_OUT_RESET_PCR called

Do you know of any reason why I would be receiving this error?

ThorbjornSomod gravatar imageThorbjornSomod ( 2017-04-26 05:02:36 -0600 )edit