with preview display on, position jumps back after stopping

[ajschult]

With preview display on (ADM_PREVIEW_OUTPUT), a video will play fine but will jump back to the initial position after playback is stopped.  gui_play's GUI_PlayAvi does this on purpose:

Code Select Expand


// If we are processing the video, the current time
// might not be matching a source video time => PROBLEM
// Go back to the beginning to be on safe ground
// In copy mode, we can keep the current position
if(getPreviewMode()!=ADM_PREVIEW_NONE)
  admPreview::seekToTime(oldTimeFrame);


After seeing this, I was going to track down what would be needed to make this work, but I have been unable to identify any problems that happen if the two lines of code are removed.  The video stops, the display switches back to non-preview (position seems to jump forward a bit, but that happens with or without preview).  I tried the Resample FPS filter, thinking it might be problematic, but that it was still fine.

Are there still problems the current code is avoiding by jumping back?