ACZoom  ·  Archive-2016

Nothing like fiddling with MPEG packets on a rainy Saturday afternoon!

This post will be periodically updated, until a reasonably easy, scripted list of steps is documented, on how to make a DVD out of video recorded on a Linux system.

TV Receiver and MPEG2 Encoder: Hauppauge WinTV-PVR-150 (MCE Editon)
This is supposed to be for Windows Media Center Edition only, so will not install on any other Windows operating systems, but works fine on a Linux computer! There is something amazing about that sentence - will not work on Windows, works on Linux! How far has Linux come...

Software: dvdauthor, avidemux2, mkisofs, growisofs, ivtv-drivers, xine, etc
And running on a Fedora FC5 Linux system.

The goals of the steps are to use scripts to save MPEG encoded video, and then perform simple editing - cut out portions not needed, and create a simple DVD structure. Avoid transcoding of video - sure, it is technically possible to get lower bit rates from higher bit rate video, but the quality reduction using transcoding is pretty drastic (possibly because it is very complex with many possible ways to do this), so best to capture at rates desired, and make sure no intermediate step involves transcoding.

Procedure:

1. Record video as needed, using the script shown elsewhere here - copy video for given duration. In the scheduled command, use ivtvctl commands to set bitrate, tune to correct channel. Choose a DVD-compatible bitrate, for example, I use 6Mb/sec CBR for capturing NTSC Standard-Definition video.
2. Load up the clip in avidemux2, cut out all ads or portions that are not needed. The avidemux2 pages have good tips on how to make cuts that wll allow the video frames to be just copied - place both A and B marker on I-Frames of the MPEG stream, and then cut.

Needed a simple script to copy video data for a fixed amount of time.

A shell script is available on ivtv driver page at Example script to schedule recordings, but wanted to do something without sending kill signals, so here's a script using the alarm signal.

Here's a perl script: timed-copy that uses an alarm signal instead of kill.

To use this, save the contents of the timed-copy link as text file, make it executable, and fix the perl path in line 1 if needed, and it is then ready to run.

I use this for capturing PVR-150 MPEG2 encoded video, by running something like this:
  timed-copy -v -m 30 < /dev/video0 > `date +%b%d-%H%M`.mpg
and scheduling this with the at command, for example:
  at -v 1:30AM Sep 14
which will end up creating a file named Sep14-0130.mpg.

Simple! Beats installing large, complex packages to do simple recordings.

Run as timed-copy -h to get help on all arguments, use -v to get verbose messages, and -v -v to get debug messages also.
Version 1.2 added a --clock option to use elapsed wall clock instead of alarm(), if needed.
Version 1.3 fixed the problem with alarm() - Time::HiRes has issues with alarm times, if the conversion to microseconds is greater than 2^32. Fix is to eliminate use of Time::HiRes, since the higher time resolution is not needed for this script, and a resolution in seconds is fine. Script now uses the default alarm() which works fine. So, the --clock option should no longer be needed.

Tested on a Fedora FC5 Linux system.