[Ffmpeg-devel] ffmpeg/rtsp - dropped videoframes

Tue Dec 5 16:21:19 CET 2006

Hi,

I'm using ffmpeg to transcode the video stream of a network camera but the
resulting video is not useable because according to the verbose output
almost all frames are dropped.

./ffmpeg-export-2006-12-05/ffmpeg -v 7 -i
"rtsp://62.99.205.199:554/flvga999.mp4" test.mpg

  configuration:  --enable-x264 --enable-gpl --enable-pp 

  libavutil version: 49.1.0

  libavcodec version: 51.25.0

  libavformat version: 51.6.0

  built on Dec  5 2006 16:59:25, gcc: 4.1.1

[NULL @ 0x84dc878] video codec set to : mpeg4

[rtsp @ 0x844a734]hello state=0

Input #0, rtsp, from 'rtsp://62.99.205.199:554/flvga999.mp4':

  Duration: 00:00:00.0, start: 0.000000, bitrate: N/A

  Stream #0.0, 1/90000: Video: mpeg4, yuv420p, 640x480, 1/25, 25.00 fps(r)

File 'test.mpg' already exists. Overwrite ? [y/N] y

Output #0, mpeg, to 'test.mpg':

  Stream #0.0, 1/90000: Video: mpeg1video, yuv420p, 640x480, 1/25, q=2-31,
200 kb/s, 25.00 fps(c)

Stream mapping:

  Stream #0.0 -> #0.0

Press [q] to stop encoding

*** 8 dup!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

[mpeg4 @ 0x84dc878]ac-tex damaged at 29 22

[mpeg4 @ 0x84dc878]Error at MB: 931

[mpeg4 @ 0x84dc878]concealing 387 DC, 387 AC, 387 MV errors

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!10 q=2.0 size=      62kB time=0.4 bitrate=1410.8kbits/s dup=9
drop=19    

*** drop!

*** drop!

*** drop!

*** drop!

*** drop!10 q=2.0 size=      62kB time=0.4 bitrate=1410.8kbits/s dup=9
drop=24    

*** drop!

frame=   11 q=2.1 Lsize=     120kB time=0.4 bitrate=2457.6kbits/s dup=9
drop=26

So I digged into the source and when if I uncomment the following code in
"static void do_video_out(.)", recompiling ffmpeg ..

/*

    if(video_sync_method){

        double vdelta;

        vdelta = get_sync_ipts(ost) / av_q2d(enc->time_base) -
ost->sync_opts;

        //FIXME set to 0.5 after we fix some dts/pts bugs like in avidec.c

        if (vdelta < -1.1)

            nb_frames = 0;

        else if (vdelta > 1.1)

            nb_frames = lrintf(vdelta);

//fprintf(stderr, "vdelta:%f, ost->sync_opts:%"PRId64", ost->sync_ipts:%f
nb_frames:%d\n", vdelta, ost->sync_opts, ost->sync_ipts, nb_

        if (nb_frames == 0){

            ++nb_frames_drop;

            if (verbose>2)

                fprintf(stderr, "*** drop!\n");

        }else if (nb_frames > 1) {

            nb_frames_dup += nb_frames;

            if (verbose>2)

                fprintf(stderr, "*** %d dup!\n", nb_frames-1);

        }

    }else

        ost->sync_opts= lrintf(get_sync_ipts(ost) / av_q2d(enc->time_base));

*/

. and running the new ffmpeg version everything seems to be working fine .

./ffmpeg-export-2006-12-05/ffmpeg -v 7 -i
"rtsp://62.99.205.199:554/flvga999.mp4" test.mpg

  configuration:  --enable-x264 --enable-gpl --enable-pp 

  libavutil version: 49.1.0

  libavcodec version: 51.25.0

  libavformat version: 51.6.0

  built on Dec  5 2006 16:09:44, gcc: 4.1.1

[NULL @ 0x84dc5f8] video codec set to : mpeg4

[rtsp @ 0x844a4b4]hello state=0

Input #0, rtsp, from 'rtsp://62.99.205.199:554/flvga999.mp4':

  Duration: 00:00:00.0, start: 0.000000, bitrate: N/A

  Stream #0.0, 1/90000: Video: mpeg4, yuv420p, 640x480, 1/25, 25.00 fps(r)

File 'test.mpg' already exists. Overwrite ? [y/N] y

Output #0, mpeg, to 'test.mpg':

  Stream #0.0, 1/90000: Video: mpeg1video, yuv420p, 640x480, 1/25, q=2-31,
200 kb/s, 25.00 fps(c)

Stream mapping:

  Stream #0.0 -> #0.0

Press [q] to stop encoding

[mpeg4 @ 0x84dc5f8]ac-tex damaged at 14 22

[mpeg4 @ 0x84dc5f8]Error at MB: 916

[mpeg4 @ 0x84dc5f8]concealing 387 DC, 387 AC, 387 MV errors

[mpeg4 @ 0x84dc5f8]ac-tex damaged at 7 24

[mpeg4 @ 0x84dc5f8]Error at MB: 991

[mpeg4 @ 0x84dc5f8]concealing 317 DC, 317 AC, 317 MV errors

frame=  395 q=31.0 Lsize=     784kB time=15.8 bitrate= 407.5kbits/s dup=0
drop=0    

video:778kB audio:0kB global headers:0kB muxing overhead 0.760837%

. the question is now where the problem could be located (rtsp stream, sdp
and/or ffmpeg). For the moment I totally lost because I have no idea how to
fix this problem but maybe you could provide me some hint(s), because with
VLC and realplayer everything works pretty well.

Regards

// Clemens

PS: Maybe the SDP is useful too .

sdp=v=0

o=- 1476600421 1165507137 IN IP4 62.99.205.199

s=flqvga999.mp4

u=<No Url>

e=<No Email>

c=IN IP4 0.0.0.0

t=0 0

a=control:rtsp://62.99.205.199/flqvga999.mp4

a=range:npt=0.000000-

m=video 0 RTP/AVP 97

b=AS:999

a=range:npt=0.000000-

a=rtpmap:97 MP4V-ES/1000

a=control:rtsp://62.99.205.199/flqvga999.mp4/trackID=11

a=control:trackID=11

a=fmtp:97
profile-level-id=3;config=000001B003000001B50900000100000001200084400668A021
E0A21F