I'm sharing my /myth directory over SMB. Is it safe to copy the .mpg files in /myth/tv to another computer, edit them, and then copy them back? I'd like to use Virtualdub on Windows to trim out the commercials.

I tried Mythtv's commercial skipping but it wasn't accurate and I find it less of a hassle to just skip commercials with the remote rather than use the remote to compensate for inaccurate skipping.

Plus, unless I misunderstand, automatic commercial skipping doesn't actually reclaim the disk space. So for stuff that I'd like to keep around to re-watch I think it'd be simplest just to pull it over to a Windows box and "crop" it then put it back with the same file name.

Is there anything in Mythtv that might get confused if the file size and runtime change?

Myth already has a feature to crop commercials. It's transcoding.

http://www.knoppmythwiki.org/index.php? ... oEditHowTo

The only problem I've had with this is that transcoding wouldn't work for me at first. I had to update a mysql table to fix it. After that, transcoding worked but it lowered the quality.

I switched to using lossless but it just didn't transcode at all. For me, it's not an issue since the burn to dvd works fine and cuts commercials.

I tried that a while back and it caused mythfrontend to crash way to frequently.

I may buy a sound card and give it a try. Right now transcoding is a no-go for me because I'm using a PVR-350 for playback so I don't get any sound when playing divx files in Myth Video. I assume that if I transcode a Myth TV recording I will also lose sound.

I tried hooking my Edirol UA-5 to my Myth TV server, but although it was recognized it wouldn't produce any sound, no matter what I did. Maybe I'd have better luck with a PCI sound card, but I haven't got time to research sound cards and I have the worst luck at picking Linux compatible hardware.

So for the time being, I'm hoping I can just use the tools I already have (Samba, Windows, Virtualdub) to quickly trim out commercials.

Really? It crashes?

I wouldn't think the sound is lost. The sound should still be in the recording, so transcoding it shouldn't remove it. I'm not sure why your sound doesn't work though. Of course, I definitely not an expert here.

Well, what you can always do is stick them in the video directory after clipping them if nothing else works. It's not nearly as elegant but it's still good.

Or mark the commercials of a set of shows and, without transcoding, compile a dvd iso out of them using a cut list. Make an iso out of a bunch of similar shows.

Do you have the sound from the PVR-350 looped through your on system sound? That could be a reason you aren't getting any sound. I'm assuming you have on-board audio.

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LinHES 8.4.3 Backend on MSI Z97 PC Mate with Pentium CPU, 16 GB DDR3 RAM, Two HD Homeruns + One HD Homerun Prime, 20 TB of storage

Nope, you assume wrong. The only audio hardware in this server is on the PVR350. I might buy a sound card if I can find one that's got an iron clad guarantee of Linux compatibility, but I'm getting sick and tired of buying hardware that only "sort of" works with Linux. I'm holding off on buying additional hardware for the moment.

Right now, playing back mpg files that were recorded with the PVR350 works and I get fully video and sound. Playing back files using mplayer or xine produces video but no sound. I know I did try transcoding and recording wouldn't play (right, or at all, I don't remember which) after transcoding. I don't recall whether that was before or after the most recent re-install.

I can also transfer the same mpg files to my Windows laptop and play them "on the go" with full video and sound.

I don't know when I'm going to get around to researching sound cards, installing a soundcard, and mucking around with the potential configuration nightmare that happens whenever I fiddle with settings on Mythtv.

I'm hoping I can save a bit of disk space quick and dirty by just trimming out the commercials using Virtualdub's "direct stream copy". With that setting, it shouldn't do any encoding whatsoever, it should just clip out whatever frames I mark as commercials.

I'm fairly confident that Virtualdub won't muck with the format of the file at all. I just wonder if Mythtv stores recording duration information in a database or anywhere else. I don't want Mythtv getting confused by having the .mpg files smaller and shorter than what Mythtv thinks they should be.

I believe the duration of shows are stored in the mysql database along with practically everything else. Not positive about it, but it would make sense to store it there.

There are some free front ends for mysql available too.

I would recommend that you do not edit MPEG2 files externally. This will invalidate the main indexing points for the recording in the database and screw up your ability to navigate in the recording (FF, skip ahead, skip back, ...) The start/end marks are particularly critical for this.

Shoot, I was afraid of something like that.

Well, if anyone happens to know of a way to get Mythtv to automatically rebuild that database info by re-reading the modified files let me know.

I'll give Mythtv's editing another try to see if the frequent crashing issue has gone away.

Good news, the editing function doesn't seem to crash mythfrontend anymore. I guess that all the crashing was probably before 0.19 and I don't think I tried it after the most recent re-install.

In addition, there's a checkbox in the transcoder config that says "lossless" and when I use that I don't lose sound.

A sound card is still on my list of future purchases, but for now I can trim out commercials while still getting sound output without needing a sound card.


BTW, if I don't check that "lossless" checkbox I do find my .mpg transformed into a .nuv file that plays without sound on my PVR350 Mythtv box and won't play at all on Media Player Classic on Windows.

If your looking for a Sound Card that has Iron Clad Support in Linux.. Look for a Sound Blaster 16 They have to be one of the best supported cards ever

mythcommflag --rebuild -f file.mpg

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| Nigel Pearson, nigel.pearson.au@gmail.com
| "Things you own end up owning you" - Tyler, Fight Club

Be warned, unless things have changed very recently, that utility will not recreate missing start and end marks for PVR recordings. My experience with it has always been that without those it will run essentially forever without making any progress.

BTW - I'd love to learn that this now works properly.