[vlc-devel] RTSP trickplay - libvlc_media_player_set_rate support for fast forward/rewind

Nuno Mota ee05154 at fe.up.pt
Sun May 29 02:59:30 CEST 2011

So i've been using VLC java bindings for a few days to create a RTSP client
to work with my Live555 RTSP Server implementation.

Both commands play and pause work fine for me. Seek is working fine and the
playback works great after all these commands. However there's a few remarks
relating to fast forward and fast rewind. Fast forward works fine, it moves
along great but sometimes the current media position is set to values way
back the timeline. When I issue the command setRate(1), the video is played
again at the same rate but it skips some frames I think, because the
playback looks a little bit jumpy. I always get the same output when i do

libdvbpsi error (PSI decoder): TS discontinuity (received 10, expected 15)
for PID 0
libdvbpsi error (PSI decoder): TS discontinuity (received 10, expected 0)
for PID 4095
libdvbpsi error (PSI decoder): TS duplicate (received 12, expected 13) for
PID 17

I see no other issues concerning Fast forward. Relative to fast rewind the
source code in the control section in media_player.c in line 1149

int libvlc_media_player_set_rate( libvlc_media_player_t *p_mi, float rate )

    if (rate < 0.)
        libvlc_printerr ("Playing backward not supported");
        return -1;

Playing backwards is not supported playing from a disc file, i've tested it
myself, however, when streaming from an Internet source the case is quite
different. I commented the above lines to produce something similar to fast
forward and the result was successful.

PLAY rtsp:// RTSP/1.0
CSeq: 11
User-Agent: LibVLC/1.1.9 (LIVE555 Streaming Media v2010.11.17)
Session: 68C9705
Scale: -2.000000

RTSP/1.0 200 OK
CSeq: 11
Date: Fri, May 27 2011 14:41:49 GMT
Scale: -2.000000
Session: 68C97056
RTP-Info: url=rtsp://;seq=13622;rtptime=210151468

The playback was as good as the fast forward results. So here's my question
why is it still not supported for streaming? I see no other problems as the
ones that exist to still make this not supported. I'm kindly accepting
responses and comments and other stuff to make this a more interesting

Nuno Mota
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.videolan.org/pipermail/vlc-devel/attachments/20110529/005cb660/attachment.html>

More information about the vlc-devel mailing list