Switching between NTSC and PAL

[barakori]

I'm a new user of both GB-PVR and MediaMVP. I want to be able to watch both NTSC and PAL content.

I looked at the GB-PVR settings, and couldn't find a place where NTSC/PAL can be selected. I noticed an option called <MVPVideoStandard> (which is set to 'auto') in config.xml, but it has no affect. How do I know? I transcoded an AVI using FFMpeg with exactly the command line specified in <MVPFFmpegTranscodeCmdLineNTSC> (The AVI is 23.976 fps, so it's better to transcode as NTSC), and the result played with blocks of errors - the same error I got when I tried playing an NTSC MPG file on the MediaMVP while it was set to PAL (with Hauppauge's server software, before using GB-PVR).

I tried setting the <MVPVideoStandard> to 'ntsc' (and restart both the recording server and the MVP), but it stayed in PAL. I confirmed this by stopping GB-PVR, starting the original Hauppauge server and switched to NTSC. Then I restarted GB-PVR and the MVP, and indeed, it was in NTSC - now NTSC movies played fine, and PAL movies were distorted.

There's a post that addresses this issue: http://forums.nextpvr.com/showthread.php...t=pal+ntsc - see comment #22. While this would work, I don't want to transcode my NTSC stuff to PAL.

Why? The NTSC stuff is usually film based, so it's 23.976 fps (let's say 24 fps for simplicity), if I transcode to PAL, the transcoding process would add an extra frame every second, and this is quite annoying, especially when the camera is panning from side to side (Note: real conversion from film to PAL usually means speeding up the projection to 25 fps, I don't know if FFMpeg can do that - it requires careful handling of the sound, as it has to be resampled for this).

So, I have a question, and a wish:

Question: Is there a way to switch between PAL and NTSC using GB-PVR and the MediaMVP? It would be best if I don't need to rstart the unit when doing so.

My wish: That the 'auto' option would work like a multisystem DVD player - when a 23.976 or 29.97 fps content is detected - the unit broadcasts it in NTSC, when a 25 fps content is detected, the unit broadcasts it in PAL. Some DVD players allow for on-the-fly conversion between PAL and NTSC but (for the reasons explained above), you loose quality in the process.

Note: My intention is to mainly use PAL content from ripping my toddlers DVD collection (their DVD scratching capabilities are extremely high, so I want to keep the media as far from them as possible), so I expect no transcoding on PAL content.

[sub]

You can only switch between PAL/NTSC using the original Hauppauge MVP software. GB-PVR will just use whatever setting was last used in the Hauppauge software.

GB-PVR doesnt really have any control over this.

[barakori]

I see, but you do understand the limitation of this configuration, right? Even if the GB-PVR is connected to a TV directly (no MediaMVP in the picture), it should switch between PAL and NTSC based on the content (any $60 DVD/Divx player does that), otherwise, if someone expects high quality video, he'll have use a DVD/Divx player, and loose all the wonderful features of the GB-PVR.

(I was hoping the <MVPVideoStandard> setting hinted that this was being considered)

[sub]

Sorry, I understand you're wanting to do, but its just a limitation you'll have to live within when using an MVP. Its not a problem on a PC connected to the TV itself.

The <MVPVideoStandard> setting was used in some MVP client software that I wrote and abandonded a long time ago.

[barakori]

I'm very sad to hear that :-(

Still, I would reiterate this is also a PC to TV problem as well: I don't know how GB-PVR plays its video, but if it's using DirectShow (for example), the playback is synchronized to switch frames only on the vertical blank, which means if the monitor is set to 60hz, PAL movies look a bit jumpy. If it's set to 75 hz, NTSC movies look jumpy. If you don't switch the frequency to match the movie frame rate (or some multiplication of that), you're loosing some quality in the process.

I wouldn't even think about what happens to an interlaced NTSC signal that's played at PAL speed - fortunately, most US shows are using 24 progressive fps these days.

Okay, I'll have to live with that, and do PAL speedup for NTSC content I watch. Oh, I'll have to re-synchronize any subtitle files I use :-(. BTW, I was very happy to see that you can attach SRT subtitles to MPG files. I couldn't even get VLC to do that.

[sub]

Still, I would reiterate this is also a PC to TV problem as well: I don't know how GB-PVR plays its video, but if it's using DirectShow (for example), the playback is synchronized to switch frames only on the vertical blank, which means if the monitor is set to 60hz, PAL movies look a bit jumpy. If it's set to 75 hz, NTSC movies look jumpy. If you don't switch the frequency to match the movie frame rate (or some multiplication of that), you're loosing some quality in the process.

I understand what you mean, but to be fair - PCs do a pretty good job with it. I dont even think you'd notice. Both NTSC or PAL video look smooth to me on my PCs (even though I know their is no direct ratio between fps and videocard fresh rate).

[barakori]

I have to agree. If you set your display card to 100Hz (for example), each PAL frame is exactly 4 frames (perfect), and a film frame would be either 4 or 5 frames. The difference is only 1/100 of a second - hard to notice.

But that's true only if you see it on a computer monitor capable of 100 progressive frames per seconds (many do). The moment you connect the card to a TV, the VGA-to-TV circuit of your video card has to obey the 50i or 60i frame rate, and we're back to what I was complaining about. I may be too sensitive, but for me it's quite annoying.

And I'm sorry for complaining so much for such a point (GB-PVR is amazing!) but I really can't watch movies on my computer monitor - it's too small. I love my 32" Wide TV and watching movies on it is unlike watching movies on my 15" laptop screen.

[sub]

The moment you connect the card to a TV, the VGA-to-TV circuit of your video card has to obey the 50i or 60i frame rate, and we're back to what I was complaining about. I may be too sensitive, but for me it's quite annoying.

No, I think that works pretty well. PC generally do a really good job with this in my experience. I regulalry watch NTSC and PAL videos on my TV, and the PC does a great job - I dont notice it at all.

Videophiles may not be happy, but to my eyes and the majority of people I know - it looks just fine.

[barakori]

Hmm, in that case, can you tell me what settings you use to transcode? I'm talking about the <MVPFFmpegTranscodeCmdLinePAL> and <MVPFFmpegTranscodeCmdLineNTSC> lines (assuming you use FFMpeg for on-the-fly transcoding). Thanks.

[sub]

I was talking about viewing on the PC above (tried to be clear about that). The MVP sucks when you try to use an NTSC video on PAL configured MVP or vice versa, so unfortunately you'll need to try to stick to the correct standard.

I pretty much only use PAL MPEG2 video (recorded here) on my PAL MVP, so cant really give you too much advice on the transcoding front, which is only used for AVIs etc.