codeblog code is freedom — patching my itch

8/2/2006

mythtv cutlist to mplayer EDL file

Filed under: Multimedia — kees @ 8:47 pm

I was too lazy to walk over to my TV, so I decided to watch my MythTV recordings on my desktop without having installed a MythTV frontend. Via the magic of MythTVfs, I started watching a recent Stargate episode.

Before the opening credits had finished, I knew I was already going to miss MythTV’s commercial flagging. So started the investigation into where in the world MythTV stores that information. I was imagining adding “.edl” files to MythTVfs automatically, etc.

In MythTV 0.19, using “mythcommflag”, you can get the “Cut” list, but not the “Commercial Skip” list. (Think of the latter as a “Cut Hint” list.) The command for this is:

mythcommflag –getcutlist -c 1059 -s 20060728210000

In MythTV 0.20, you’ll be able to use “–getskiplist”. Since I’m still using 0.19, I had to go directly to the “mythconverg” database to get the details. The marks are stored in the “recordedmarkup” table. The mark types I care about are: 4: Commercial Start, 5: Commercial End. This SQL query gets me somewhere:

SELECT mark, type FROM recordedmarkup WHERE chanid = “1059” AND starttime = “20060728210000” AND (type = 4 OR type = 5) ORDER BY mark;

However, mplayer’s EDL file format expects time, not frame number. MythTV stores frame number. Luck for us, it’s all NTSC MPEG2, so we’re at 29.97 frame per second, and I can modify the SQL:

SELECT mark/29.97, type FROM recordedmarkup WHERE chanid = “1059” AND starttime = “20060728210000” AND (type = 4 OR type = 5) ORDER BY mark;

Now I just have to get the pairs on a single line with a trailing “0” for mplayer to know to skip that time frame:

echo ‘SELECT mark/29.97 FROM recordedmarkup WHERE chanid = “1059” AND starttime = “20060728210000” AND (type = 4 OR type = 5) ORDER BY mark;’ | mysql -B –skip-column-names | xargs -l2 | awk ‘{print $0 ” 0″ }’

Combined with some logic to extract the channel and starttime for a given recording, I’ve now got a really crazy wrapper script that’ll let me mplayer a recording after generating an EDL cutlist.

(With thanks to Ken’s excellent collection of “merge pairs of lines into single lines” short cuts.)

© 2006, Kees Cook. This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 License.
Creative Commons License

2 Comments »

  1. A year and a half after your post, I’m thinking of using your script to use mythcommflag with SageTV on Linux. My suggestion is that rather than assuming that the frame rate is 29.97 (which it might not be for say, HD recordings), you could use ffmpeg to determine the frame rate. For mpeg2 files ffmpeg -i recordedfile.mpg 2>&1 | grep “Stream #0.0” | sed “s/^.*kb\/s, //;s/tb(.)//” seems to spit out the correct number. It doesn’t work for recordings transcoded to nuv though.

    Comment by Shanti Kulkarni — 2/22/2008 @ 4:57 pm

  2. This works pretty well, actually:

    $ mplayer -vo null -ao null -identify -frames 10 -quiet $FILE 2>/dev/null | grep ^ID_VIDEO_FPS
    ID_VIDEO_FPS=29.970

    Comment by kees — 12/16/2010 @ 6:42 pm

Leave a Reply

Your email address will not be published. Required fields are marked *

Powered by WordPress