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PostPosted: Fri Feb 02, 2007 5:20 am 
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Location: Swansea, UK
I can't believe that MythArchive is as bad as it seems to be! I mean, yes the GUI is clunky and slow, but that will no doubt improve.

I'm talking about the apparent inability of MythArchive to make a usable DVD of UK DVB-T programmes - specifically those transmitted on ITV or Film4. I'm not sure about BBC at the moment.

I have noticed a couple of things about ITV/Film4 that are of interest:

1) ITV/Film4 always seems to flag its transport-stream (TS) bitrate at being 15Mb/sec (!) In practice, the stream is rarely much over 6Mb/sec from what I've seen.

2) ITV/Film4 always seem to transmit in 704x576 mode, the BBC always seem to use 720x576. (Both of these are valid formats for DVD by the way).

I'm confused as to why MythArchive is having trouble as it seems at least to be doing the "right thing". First stage of it building a DVD is to run mythtranscode with the --mpeg2 flag to convert from TS to PS (programme stream), and I know mythtranscode does this bit right because I've tried it by hand and the resulting PS will go on a DVD and play just fine if I do all the necessary dvdauthor work myself. And this is despite the ITV-sourced PS files claiming the bogus 15Mb/s bitrate....

If I try authoring a DVD with MythArchive though (using the "don't re-encode" option), the resulting disk plays the start of the programme's soundtrack whilst displaying the "MythTV" start logo and (IIRC) during the title menu. When the programme itself starts playing, the picture is all chopped up about twice a second by a burst of on-screen interference (can't remember what happens to the sound, though IIRC it seemed synchonised with what the picture was doing behind the bursts of noise).

It's as if the disk got mastered with the TS not the PS of the programme, though 'mplayer' claims that it is decoding a PS at that point.

Anyone else seen this?
Any comments about the bogus ITV datarate, or can I discount that as being anything to do with the issue? As I say, I've hand-authored DVDs despite it.

I notice (with ITV at least) that MythArchive doesn't seem to offer me the "SP", "LP" and "EP" re-encoding options for my disk. I do believe that I've made an "LP" disk off a BBC programme at least once in the past.

Also - I notice that MythArchive's guess as to the amount of storage needed on the DVD is wrong - it looks to be using the filesize of the transport-stream for its calculations, not allowing for the fact that the programme-stream might be up to a gigabyte smaller.

In fact, this posting would have been a lot smaller if I'd listed what MythArchive did *right*! :-) I'm going to guess that the author(s) of MythArchive are in the 'States or Canada and that it all works fine with ATSC cards, PVR-250 cards and .nuv captures from analog input cards.


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PostPosted: Fri Feb 02, 2007 7:53 am 
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Location: London, UK
Hi Steve,
I'm using DVB-T cards to record programmes here in London and not had any problems. Saying tat I'm using R5D1 + 0.20. Mytharchive has a very clunky interface.
I've burnt off a number of recording using it and not had any coasters. I'll get you a second opinion on ITV1 / Film4 as the last thing I burnt off was Back to the Future 1, 2 & 3, recorded from ITV1 I think. That'll have to wait though as I'm not near my machine right now.

But, I've certainly burnt off programmes using the "Don't Re-Encode" option and from recollection they work - most of what I put onto a DVD is from Film4.

Have you set your recording options correctly? Have you told Myth you are using PAL for your recordings? Set your recording profiles to 720x576?

I would be surprised if the advertised bit rate of the programmes would make any difference to the recording you get.

When you say that MythArchive gets it wrong on the size are you transcoding out the adverts before authoring the DVD or letting MythArchive do the cuts once you've marked them?

As I say, I'll check when I get home.

What version of KnoppMyth are you using?

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PostPosted: Fri Feb 02, 2007 11:01 am 
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Location: Swansea, UK
Hello Tophee:
My system details are now in my .sig (see below).
I've set up for PAL (though actually it's DVB-T of course, not the same thing but Myth doesn't seem to differentiate). I've not forced 720x576 because that's not something I can do with DVB-T. The transport stream is 704x576 on ITV, like it or lump it. Transcoding isn't really an option (would degrade the picture), and I can't "capture" in any other form than the way they send it.

This isn't like capture of analog TV where I can call the shots.

Anyway, I can make DVDs from ITV's programmes. I just have to do mythtranscode --mpeg2 to get them from TS to PS, then use dvdauthor (actually dvdstyler, much nicer!) to do the rest - as I said.

I just can't seem to get MythArchive to do it.

_________________
ChainTech 6ATA2 MoBo (533MHz PentiumIII Katmai, Via VT82C693A/686A chipset)
20Gb UDMA33 disk.
R5E50 plus keyboard fixes for UK.
1x Hauppauge Nova-T DVB-T card.
1x Bt848 Analog capture card.
SIS 6326 AGP2x Video card (too slow for watching TV).


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PostPosted: Fri Feb 02, 2007 12:48 pm 
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Location: UK
I've found interesting problems with ITV4. After recording a programme ("Wanted"), I've marked the Ads and transcoded using lossless to produce a file which is a good bit less than 1Gb. in size. On replay, playback is OK, but any fast forward shows an interesting effect.
Trying to burn on to a DVD (no transcode), the size is shown at the new size but the gauge at the side shows 2+Gb for the file.

Bruce S.

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PostPosted: Fri Feb 02, 2007 2:01 pm 
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Joined: Tue Sep 13, 2005 10:48 am
Posts: 852
Location: London, UK
Well, as promised, I checked the last thing I authored using MythArchive from ITV1 (it was Back to the Future) and no problems.

I understand that you get what you get in terms of what they broadcast, PAL should be 720x576. I've set Myth to record in that format.

As to bruce_s01comments about the fastforward... that's probably due to the flakeyness of the internal player.

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PostPosted: Sun Feb 04, 2007 4:51 am 
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Joined: Sat Nov 12, 2005 3:52 pm
Posts: 65
Steve Hosgood wrote:
I can't believe that MythArchive is as bad as it seems to be! I mean, yes the GUI is clunky and slow, but that will no doubt improve.

I'm talking about the apparent inability of MythArchive to make a usable DVD of UK DVB-T programmes - specifically those transmitted on ITV or Film4. I'm not sure about BBC at the moment.

I have noticed a couple of things about ITV/Film4 that are of interest:

1) ITV/Film4 always seems to flag its transport-stream (TS) bitrate at being 15Mb/sec (!) In practice, the stream is rarely much over 6Mb/sec from what I've seen.

2) ITV/Film4 always seem to transmit in 704x576 mode, the BBC always seem to use 720x576. (Both of these are valid formats for DVD by the way).

I'm confused as to why MythArchive is having trouble as it seems at least to be doing the "right thing". First stage of it building a DVD is to run mythtranscode with the --mpeg2 flag to convert from TS to PS (programme stream), and I know mythtranscode does this bit right because I've tried it by hand and the resulting PS will go on a DVD and play just fine if I do all the necessary dvdauthor work myself. And this is despite the ITV-sourced PS files claiming the bogus 15Mb/s bitrate....

If I try authoring a DVD with MythArchive though (using the "don't re-encode" option), the resulting disk plays the start of the programme's soundtrack whilst displaying the "MythTV" start logo and (IIRC) during the title menu. When the programme itself starts playing, the picture is all chopped up about twice a second by a burst of on-screen interference (can't remember what happens to the sound, though IIRC it seemed synchonised with what the picture was doing behind the bursts of noise).

It's as if the disk got mastered with the TS not the PS of the programme, though 'mplayer' claims that it is decoding a PS at that point.

Anyone else seen this?
Any comments about the bogus ITV datarate, or can I discount that as being anything to do with the issue? As I say, I've hand-authored DVDs despite it.

I notice (with ITV at least) that MythArchive doesn't seem to offer me the "SP", "LP" and "EP" re-encoding options for my disk. I do believe that I've made an "LP" disk off a BBC programme at least once in the past.

Also - I notice that MythArchive's guess as to the amount of storage needed on the DVD is wrong - it looks to be using the filesize of the transport-stream for its calculations, not allowing for the fact that the programme-stream might be up to a gigabyte smaller.

In fact, this posting would have been a lot smaller if I'd listed what MythArchive did *right*! :-) I'm going to guess that the author(s) of MythArchive are in the 'States or Canada and that it all works fine with ATSC cards, PVR-250 cards and .nuv captures from analog input cards.


<RANT>
<Sigh> It's comments like these that makes me wonder why I bother to contribute to the MythTV project. Before I started to work on Myth I used to read the lists and wonder why the devs often seemed to be angry and abrupt when replying to questions, from being on the other side of the fence for a while I can see why now :!: May I remind you of how much you payed for this software :x I'm also from the UK :!:
</RANT>

If you can PVRx50 is the way to go if you want to archive recordings to DVD using MythArchive, I get close to 100% success rate here using good quality blank media.

With DVB-t some people have good success others have problems. I haven't been able to reproduce any of the reported problems yet even when people have supplied a recording that they swear won't work so haven't looked to hard to fix it. Comments like the above doesn't fill me with much enthusiasm to fix things either :lol:


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 Post subject: Not a rant - honest
PostPosted: Sun Feb 04, 2007 5:17 pm 
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Posts: 17
Location: Swansea, UK
Paulh:
Experience has taught me that it's a waste of time to rant back at a ranter. So I won't, and I'll respect the fact that you are a mythtv developer.

As yet I've not contributed to MythTv. I will do, I'm sure. MythTv is a great project - does lots of things well. Other things it does (or tries to do) it sucks at. I don't consider that a failing - it only advertises itself as being version 0.20 dammit.

What's going on in this thread (in case you hadn't read it properly) is that I, a UK based DVB-T user, is having trouble with MythArchive, and wondering it that's because I've screwed up somehow or whether other DVB-T people (UK or anywhere else) are having the same trouble.

My first lines of the thread point out "I find it hard to believe MythArchive is as bad as it seems to be" - hinting at my confidence that a mainstream MythTv module would normally work as advertised, and that the fault is probably something local to me.

Off your high horse, 'paulh'. MythArchive is new. Of course there's things wrong with it. That's not a personal insult to you or any other developer. That's just reality. Use comments like mine (and the others here) either to debug things and make them better or to show me where I've misused the thing and that there's no surprise it doesn't work.

I'm a developer too. Not on MythTv, not yet. But I don't go ranting at people who point out flaws in my work. I use their comments.

You might like to try it sometime.

_________________
ChainTech 6ATA2 MoBo (533MHz PentiumIII Katmai, Via VT82C693A/686A chipset)
20Gb UDMA33 disk.
R5E50 plus keyboard fixes for UK.
1x Hauppauge Nova-T DVB-T card.
1x Bt848 Analog capture card.
SIS 6326 AGP2x Video card (too slow for watching TV).


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 Post subject: File sizes
PostPosted: Sun Feb 04, 2007 5:49 pm 
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Location: Swansea, UK
Bruce_s01:
The discrepancy between file sizes is presumably due to MythArchive still showing the size of the unedited Transport Stream (TS) for the programme wheras what's burned to DVD is the edited Program Stream (PS) for the thing.

Even without chopping out the adverts, TS is likely to be 15% - 20% bigger than the corresponding PS.

_________________
ChainTech 6ATA2 MoBo (533MHz PentiumIII Katmai, Via VT82C693A/686A chipset)
20Gb UDMA33 disk.
R5E50 plus keyboard fixes for UK.
1x Hauppauge Nova-T DVB-T card.
1x Bt848 Analog capture card.
SIS 6326 AGP2x Video card (too slow for watching TV).


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 Post subject:
PostPosted: Sun Feb 04, 2007 7:36 pm 
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Joined: Tue Aug 08, 2006 7:08 pm
Posts: 561
Location: UK
Steve, thanks, but looking at the following
Code:
bruce@homenet-pvr:~$ ls -l /myth/tv/1736*.mpg
-rw-r--r-- 1 mythtv mythtv 1427083372 Jan 28 22:00 /myth/tv/1736_20070128210000.mpg
-rw-r--r-- 1 mythtv mythtv 1529752992 Feb  4 22:00 /myth/tv/1736_20070204210000.mpg

Before lossless transcoding and this:
Code:
bruce@homenet-pvr:~$ ls -l /myth/tv/1736*.mpg
-rw-r--r-- 1 mythtv mythtv 694435844 Feb  5 01:32 /myth/tv/1736_20070128210000.mpg
-rw-r--r-- 1 mythtv mythtv 772339716 Feb  5 01:37 /myth/tv/1736_20070204210000.mpg
after, there does seem to be some issue there. Though I haven't tried Archiving with these files yet
Since the c/o to R5E50, I don't think I've burnt any DVB-T programmes to disk yet, other than "Wanted". I'll have to keep an eye out for this.
I'm wondering if the file is still TS and having bits cut out at the start and in programme for ads is what is giving the viewer app indigestion?

Bruce S.
Editied to correct status of files.

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 Post subject: File sizes
PostPosted: Mon Feb 05, 2007 8:27 am 
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Posts: 17
Location: Swansea, UK
Bruce_s01:
Those file sizes look like TS->"PS minus adverts" to me. A 1.5Gb TS would probably become 1.0-1.1Gb if transcribed to PS, and removal of 5 min of adverts every 20 min would probably account for the end result being 7.7Gb or thereabouts.

Run one of those .mpg files through 'mplayer', quit the player with 'q' and look at the report about the file and its contents. First line tells you what it was: TS or PS.

I did this myself recently. "mythtranscode --mpeg2" does the TS->PS conversion, and (though I didn't do it) can chop out marked adverts from cutlists too.

_________________
ChainTech 6ATA2 MoBo (533MHz PentiumIII Katmai, Via VT82C693A/686A chipset)
20Gb UDMA33 disk.
R5E50 plus keyboard fixes for UK.
1x Hauppauge Nova-T DVB-T card.
1x Bt848 Analog capture card.
SIS 6326 AGP2x Video card (too slow for watching TV).


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 Post subject:
PostPosted: Tue Feb 06, 2007 7:31 pm 
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Location: UK
I think I've found out what the problem was with that particular programme, it appears the frame size for "Wanted" is 544x576?! I'm assuming the 2.1 GB the gauge is showing is a guesstimate of the file size for the conversion to 720x576.

Bruce S.

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 Post subject: Transcoding TS -> PS
PostPosted: Wed Feb 14, 2007 4:41 am 
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Location: Swansea, UK
I've just noticed that if you 'mythtranscode' a programme with the --mpeg2 flag to get a TS->PS conversion, then replace the originally recorded TS with the resulting PS, then MythTV doesn't seem to mind, but internally in its database, the size of the recorded programme doesn't change.

(This assumes that you do all the above work "by hand" so to speak. Maybe there's a proper way to do that informs the database of the new file size?)

Whatever, this might partially explaine Bruce_S01's comments about MythArchive being confused as to how much space it assumes a programme will need on a DVD. Whadda y'reckon Bruce?

Meanwhile, I also noticed that BBC4 are making the same mistake of flagging their transport streams as 15Mbit/sec regardless of content. I grabbed "Life on Mars, Episode 2.2" off BBC4 last night, and the transcoded PS came out as about 1.4Gb which amounts to about 2.8Mbit/sec, but the TS said 15Mbit/sec. That sort of thing is unlikely to help.

Unlike ITV's misflagged TS, the BBC one is 720x576 as all other BBC transmissions seem to be. Interesting that they share the 15Mbit/sec issue.

It might be nice if 'mythtranscode' could have a command-line flag to rewrite the bitrate field of a PS, rather than blind copy the (possibly bogus) info from the original TS.

Steve

_________________
ChainTech 6ATA2 MoBo (533MHz PentiumIII Katmai, Via VT82C693A/686A chipset)
20Gb UDMA33 disk.
R5E50 plus keyboard fixes for UK.
1x Hauppauge Nova-T DVB-T card.
1x Bt848 Analog capture card.
SIS 6326 AGP2x Video card (too slow for watching TV).


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 Post subject:
PostPosted: Wed Feb 14, 2007 10:53 am 
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Joined: Tue Aug 08, 2006 7:08 pm
Posts: 561
Location: UK
I'm wondering if it reporting the whole mux, I don't believe even BBC1 is even close to 15Mb/s. Considering the low bit rate of some the rest of the channels, I wouldn't be surprised. Have you seen Film4+1? :)
I don't know exactly why the estimate is out, but as I said before, I think it due to the frame size not being a DVD resolution so mytharchive is guesstimating a resulting file size.
I've burnt some other DVB files to disk, I've had no problems with the estimated file sizes, other than with "Wanted".
As for the other file sizes being reported after transcoding, I've not seen any issues with that either.

Bruce S.

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Hauppauage Nova-T 500, Nova-T LinHes R8.6.1


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