[mythtv-users] Editing out commercials

Fri Oct 31 16:45:03 EST 2003

Ah, my apologies, I did not see it was already an mpeg2.
To be honest for that kind of work I move the file over to my gaming
machine which is not Linux. There I use TMPGEnc to edit without
re-encoding. If I find something I will let you know.

On Thu, 2003-10-30 at 18:27, James L. Paul wrote:
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> On Thursday 30 October 2003 12:59, Muddy wrote:
> > Not sure if this will help you or not. I've been playing around with
> > avidemux and love it. I talked to the creator of it who suggested some
> > tips that payed off.
> > I'm using your basic bt878 card (ati tv wonder) and it's turning out
> > nice recordings.
> > Here is how I'm recording and ripping.
> > Mythtv is setup as 480x352, Codec mpeg-4, bitrate 2300, max quality 2
> > minimum quality 12, max diff 3, Enable High-Quality Encoding, Audio
> > Uncompressed @ 44100.
> > Then in Avidemux I pretty much follow their "capture to svcd" guide. My
> > video is svcd processed @ Constant Quantizer=7 max bitrate 2300, audio
> > is ffmpeg audio @ 192kbps, and I do not crop per the guide as it gives
> > me wild color splashes in my video. I only use deinterlace and sharpen
> > for my filters.The half hour shows I have been ripping end up somewhere
> > around 350MB in size. The quality is quite good.
> 
> Thanks, and I am indeed aware of avidemux. However, I'm using MPEG2 hardware 
> encoding and want to edit without re-encoding. I don't believe avidemux can 
> do this.
> 
> > -
> >
> > On Tue, 2003-10-21 at 19:09, D Banerjee wrote:
> > > Sounds like you're missing the I frame after the next cut - mpeg is mpeg,
> > > if your data stream starts on an I frame it should render correctly. When
> > > you seek to I frame you may need to skip backwards one frame before
> > > making the cut. Ontopic here - mythtv can already seek to keyframes in
> > > edit mode. Should be pretty simple to write something that will simply
> > > concatenate segments..
> 
> The problem is I have not yet found a tool under Linux that can cut MPEG2. I 
> know I need to cut on an I-frame or GOP boundary, I just haven't found a tool 
> that can do this properly and result in segments that I can demux/remux for 
> DVD. Shocking, eh? ;)
> 
> mpgtx seems to be the foremost tool for cutting MPEG, but it has no working 
> method for specifying where to cut other than by megabyte. If I specify a 
> range by time, it's way way way off. Many minutes off, not even close.
> 
> GOPchop does gut the video just fine, and results in useable video segments 
> after fixing up the broken indexes with gop_fixup. But it breaks the audio 
> badly, and no other tools will recognize the mp2 audio stream.
> 
> I'd be very happy to hear the name of a linux tool that given a time index can 
> simply cut a MPEG2-PS files on I-frames.
> 
> If I could just cut the video, I could remux it for DVD and burn a DVD with 
> chapter points at each break so easily.
> 
> > > ----- Original Message -----
> > > From: "James L. Paul" <james at mauibay.net>
> > > To: "Discussion about mythtv" <mythtv-users at mythtv.org>
> > > Sent: Tuesday, October 21, 2003 6:48 PM
> > > Subject: [mythtv-users] Editing out commercials
> > >
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> > > > Perhaps this is somewhat off-topic here, but Isuspect other MythTV
> > > > users might have similar interests or experience doing what I want to
> > > > do.
> > > >
> > > > Context:
> > > > I'm only talking about MPEG2 here, specifically the streams that the
> > > > PVR-250 and such spew forth. Has anybody here suggestions for removing
> > > > commercials from recorded TV shows? I did this with various windows
> > > > tools and MPEG1 for years under Windows, and haven't found any reliable
> > > > tools in the past couple years of looking under Linux.
> > > >
> > > > Goal:
> > > > Take a MPEG2 stream recorded by PVR-250 under MythTV, edit out
> > > > commercials, result in a MPEG2 stream usable for CVD or DVD. I don't
> > > > want to re-encode. I want to simply do GOP or I-frame cuts and get a
> > > > valid usable stream. Demuxing/remuxing is tolerable if audio sync
> > > > doesn't drift. Assume that the stream specs are already appropriate for
> > >
> > > DVD.
> > >
> > > > What I've tried recently:
> > > > This week I tried avidemux, (and avidemux2, what's the difference?) but
> > > > could not get anything usable at all. I tried GOPchop, and everything
> > > > after the first cut is broken. I used mpgtx to demux the GOPchopped
> > > > file, so I could try gop_fixup to fix the broken time indexes left by
> > > > GOPchop, but gop_fixup didn't do anything at all, not even walk the
> > > > file or change a single bit.
> > > >
> > > > I used mplayer to note all the in/out points of the commercial breaks
> > > > and tried using mpgtx to split and join the file. Everything is broken
> > > > after the first cut. I tried leaving all the segments unjoined but only
> > > > the first segment was palatable to mplex and dvdauthor.
> > > >
> > > > What I ended up doing:
> > > > I had one show on the History Channel I wanted to get to my parents
> > > > right away, so I left all the commercials in and simply set chapter
> > > > marks at the end of each commercial break. Not what I wanted to do at
> > > > all. I used dvdauthor and mkisofs to generate the DVD ISO.
> > > >
> > > > Questions:
> > > > Is there a tool (under Linux) that I've missed that can do I-frame or
> > > > GOP cuts in an MPEG2 program stream and result in a correct and usable
> > > > file? (GUI or not.)
> > > >
> > > > Is there something better than mplex to generate a DVD compatible MPEG2
> > > > stream from element .m2v and .mp2 files? If not, is there a way to get
> > > > mplex to NOT split the output file at the 2G limit? (Using "-S 0"
> > > > simply doesn't do anything, it still wants to split the file.)
> > > >
> > > > Is there a tool better than dvdauthor for generating a DVD file
> > > > structure from MPEG2 file(s)?
> > > >
> > > > Thanks for any advice!
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