VBI playback - nexTView debugging tool
This is the manual page for the VBI playback debugging tool which is part of the nxtvepg software package.
vbiplay - Playback of recorded EPG teletext packets
vbiplay allows to play back a series of teletext packets received on a designated EPG page, even in regions of the world where the EPG provider normally can not be received. It can connect to nxtvepg and transfer the data into it's VBI input buffer as if they had been received life on air (however with a much higher data rate). It's a small tool that's intended for debugging EPG reception problems or decoding errors.
vbiplay takes the the place of a TV application in the communication with nxtvepg, i.e. no TV application (which supports EPG interaction) must be running at the same time or the tool will immediately exit with an error message.
vbiplay opens a file named ttx.dat which must be previously generated by vbirec. If nxtvepg isn't already running, the program waits until it is attached. As soon as nxtvepg is attached and acquisition is enabled, playback starts. It's recommended to check the reception by nxtvepg in the View acq statistics window, which can be opened in the Control menu.
The teletext packets are played back as fast as possible. However since nxtvepg only polls the teletext buffer once every second (which is enough for regular Nextview transmissions) and the buffer holds a maximum of 512 packets, the maximum data rate is limited to shortly above 20 pages per second, i.e. apx. 20 times the normal data rate.
This is the fixed name of the input file. It must be generated by vbirec.
See also the manuals for vbirec and nxtvepg.
Th. ``Tom'' Zoerner, Nuremberg, Germany.
Email: tomzo (at) users (dot) sourceforge (dot) net
Copyright (C) 2002 by Th. Zoerner. All rights reserved.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License Version 2 as published by the Free Software Foundation, e.g. at http://www.fsf.org/
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of merchantability or fitness for a particular purpose. See the file COPYRIGHT for more details.