Record video/audio and count frames

[michikommader]

Heho!
I'm new to libvlc and want to save h264-video and aac-audio from an RTSP-stream into a file plus count the recorded video frames (for logging together with data from other sensors).

My recording works well with this example but obviously I have no possibility to access any frames to count them:

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libvlc_instance_t* inst = libvlc_new(0, NULL); libvlc_media_t* m = libvlc_media_new_location(inst, "rtsp://ip-address/stream.sdp"); libvlc_media_add_option (m, ":sout=#std{access=file,mux=mp4,dst=\"outfile.mp4\"}"); libvlc_media_player_t* mp = libvlc_media_player_new_from_media(m); libvlc_media_release(m); libvlc_media_player_play (mp);

On the other hand I can count my frames using custom callbacks like described in viewtopic.php?f=32&t=110586. But this way I do not know how to mux my incoming video and audio into a file simultaneously. Is there any tutorial I can follow? Or do I have to choose a totally different approach?

I already asked on IRC today and got the hint to implement my own video output and use libvlc_video_set_callbacks together with libvlc_video_set_format. But I have no clue how to do the synchronised video- and audio-processing into my file. Maybe I am just searching for the wrong keywords. Any help and further hints are warmly welcome!

der Michi

[Jean-Baptiste Kempf]

You could use smem to get the callbacks, but that's harder.

I'm not sure if the stats are available from libVLC.

[michikommader]

Heho!

It works fine with smem and custom callbacks. For orientation I used the wiki tutorial on smem and pass a this-pointer of my handling object (where I increase the frame count) into smem's video-data-parameter:

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... sprintf(media_options, ":sout=#duplicate{dst=std{access=file,mux=mp4,dst=\"%s.mp4\"}," "dst=smem{video-prerender-callback=%lld,video-postrender-callback=%lld,video-data=%lld}}", outfile.c_str(), (long long int)(intptr_t)(void*)&cbVideoPrerender, (long long int)(intptr_t)(void*)&cbVideoPostrender, (long long int)(intptr_t)(void*)this); libvlc_media_add_option (media, media_options); ...

This allows me to access members and functions of my object within a callback. My two static video callback functions do the handling:

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void cbVideoPrerender(void *p_video_data, uint8_t **pp_pixel_buffer, int size) { *pp_pixel_buffer = (uint8_t *)malloc(size); } void cbVideoPostrender(void *p_video_data, uint8_t *p_pixel_buffer, int width, int height, int pixel_pitch, int size, int64_t pts) { //Get instance of the desired object MyFancyClass* obj = static_cast<MyFancyClass*>(p_video_data); obj->doFancyStuff(); }

The static_cast from a void pointer has to be handled with care because there is no possibility to validate my resulting object as far as I know. So obj will never be NULL after the cast but may point to a crappy object with mysterious members if something went wrong.

I wish there would be more documentation on all this ...

Michi