Useless Error Messages

The web is filled with examples of useless computer error messages.

I was migrating a system from CentOS 6 to Debian 10. The system uses vlc to display a Real Time Streaming Protocol (RTSP) video stream from an outdoor camera.

The operating system migration went well but not so well with VLC, which saw a version jump from 2.1.6 to 3.0.11. The person who installed the system and camera left behind no documentation.

On launching cvlc from within a shell script wrapper, the system logs quickly began filling with an obscure and unhelpful message [mjpeg @ 0x7f3b08157680] rc buffer underflow.

Setting the VLC log output to verbose=0 failed to stop the spew.

I found the error message string in the ffmpeg sources.

For a few hours I searched the web in vain for any clue or solution. I found only one indirect reference that helped. One person asking some years ago for the same help reported the message could be avoided by reducing the image size or changing the streaming bit rate.

I looked at the cvlc options in the shell script. I found an option vb=2048. I did not find that parameter in the ffmpeg or vlc documentation. Because the shell script is from the days of older versions of ffmpeg or vlc, I wondered if the parameter might mean video bit rate. Wasting more time searching the web indicates vb means variable or video bitrate.

On a hunch I deleted the parameter. That seemed to stop the horrific log spew.

Without that log clutter I again browsed the log output. Only to be greeted by another set of unhelpful and useless error strings.

    chain error: Too high level of recursion (3)
    main error: Failed to create video converter

These types of error messages are developer centric and never help users. The error messages fail to help users resolve the underlying root cause. Worse, when people seek help online, almost nobody replies to help.

If only error messages were actually helpful.

I can dream.

Posted: October 21, 2020 Category: Usability Tagged: General

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