[vlc-devel] Re: Doing an lseek() with VOB files ...

[j.zorko at att.net]

Jean-Paul,

<<            else
            {
                /* This can indicate that we missed a packet or that the
                 * continuity_counter wrapped and we received a dup packet:

If the continuity_counter wraps (at 16) then there is no duplicate packet! The continuity counter 
always wraps at 16 !!

                 * as we don't know, do as if we missed a packet to be sure
                 * to recover from this situation */

Why ? This is a legal situation for TS packets

                msg_Warn( p_input,
                          "packet lost by TS demux for PID %d: current %d, packet %d",
                          i_pid,
                          p_es_demux->i_continuity_counter & 0x0f,
                          p[3] & 0x0f );
                b_lost = 1;
                p_es_demux->i_continuity_counter = p[3] & 0x0f;
FILE *pFile = fopen( "//Users//jmzorko//vlc_debug.txt", "a+" );
fprintf( pFile, "* " );
fclose( pFile );
            } /* not continuous */
... I put the fopen / fprintf in system.c, and then ran the test (server VLC, client VLC, telling 
server VLC to seek and seeing what shakes with the client VLC).  The results are interesting -- 
the "*" only appeared in the vlc_debug.txt file 7 times, though I told the server VLC to seek 
dozens of times.  Does this indicate that the discontinuity bit isn't always being set by the server 
VLC?

You did not even set the bit ;-) You've got it mixed up with the continuity counter which is 
another bit in the TS header. >>

I should probably make something a bit more cogent -- the only code I added to VLC in the 
above piece is the fopen / fprintf / fclose.  Everything else was already there -- I only added the 
fopen / fprintf / fclose code to try to narrow down where the problem may be happening.  A 
quick look at modules/demux/mpeg/system.c will make this clear.

Anyway, that fopen / fprintf / fclose only happened on the client VLC 7 times during my test, 
while I seeked on the server VLC providing the stream dozens of times.  Can I infer from this 
that the server VLC, after a seek, is not setting the discontinuity bit in the TS header correctly 
before sending it out?

Regards,

John

Falling You - exploring the beauty of voice and sound
New EP, "hope thrown down," available now at
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