Problem with MPEG2 file format in recorded shows

[fooit]

Hello, forum!

I am using GBPVR to record shows from a sat box on Sapphire Theatrix T550 card (driver ver 6.14.10.86 installed). Shows are being recorded with High profile on GBPVR. All I want after a show was recorded is to trim it, remove commercials and re-encode it in MPEG4 format for space saving in the best possible quality.

Problems arise when I try to cut recorded MPEG2 files into smalled pieces and remove commercials using VideoReDo (it's the fastest proggy I've seen so far to cut MPEG2 files without full encoding process) - output files are not what I expected to see - it seems like scenes were mixed.
After some research it turns out the the GOP timestamps are not sequential in the input MPEG2 I recorded.

Owners of ATi T550 based cards - do you have this problem?
If yes - what do you do to fix it?

In general, what proggies do you use to cut commercials? What do you use to re-encode into MPEG4?

Thanks in advance!

[groover km]

videohelp.com has a loads of info on MPEG-2 editors; even free ones, including cuttermaran which I use. It's accurate and reliable, only downside being that files must be demuxed beforehand.

VirtualDub or AutoGK (again, both free) will re-encode to MPEG-4 for you.

Just as an FYI for anyone reading this, there was a 'cracked' version of VideoReDo floating around sometime ago that exhibited the problem described above - edited files remuxed out of sequence, etc. can't remember the version no., I read about it on the VideoReDo forums.

Hope this helps.

[Raffka]

Hello! I'm new to this forum. Anyway, I have the Sapphire Theatrix 550 and use cuttermaran to remove commercials. I also use ProjectX to demux mpegs. I've tried using VirtualDub Mpeg MOD to re-encode to mpeg-4 but the video quality becomes worse. Even when you re-encode from avi back to mpeg, it looks terrible (horizontal lines slicing up the video). This seems to be the only negative thing about the Theatrix 550. It's best to leave it in mpeg-2 format, which has excellent image quality.

[reboot]

Firstly, if you're going to use Cuttermaran to edit, use PVAStrumento to demux. It's the only demuxer I've found that will retain audio sync, when doing frame accurate cuts, not on I frames. Not sure if ProjectX has this ability, but check it to see.

Secondly, it's not virtualdub (mod/mpg/ac3/etc.) that's causing the quality loss, it's your mpeg-4 codec choice, and settings. The MS mpeg-4 codec is ancient, dating back to Win95, and there are much better ones around. I would suggest DivX or Xvid as better alternatives.

Thirdly, re-encoding an mpg-2 from a poor quality mpeg-4 is going to result in even worse quality. If you wanted an mpeg-2, you should have left it as such, and not tried to compress for storage to mpeg-4. It has nothing to do with your 550 (nor any other capture card for that matter).

Done right, one can get superb quality avi (mpeg-4) from a capture, with little, or no (noticable) loss in quality, but re-encoding to mpeg-2 is going to give some loss, no matter what settings you choose.

[Raffka]

Firstly, if you're going to use Cuttermaran to edit, use PVAStrumento to demux. It's the only demuxer I've found that will retain audio sync, when doing frame accurate cuts, not on I frames. Not sure if ProjectX has this ability, but check it to see.

Secondly, it's not virtualdub (mod/mpg/ac3/etc.) that's causing the quality loss, it's your mpeg-4 codec choice, and settings. The MS mpeg-4 codec is ancient, dating back to Win95, and there are much better ones around. I would suggest DivX or Xvid as better alternatives.

Thirdly, re-encoding an mpg-2 from a poor quality mpeg-4 is going to result in even worse quality. If you wanted an mpeg-2, you should have left it as such, and not tried to compress for storage to mpeg-4. It has nothing to do with your 550 (nor any other capture card for that matter).

Done right, one can get superb quality avi (mpeg-4) from a capture, with little, or no (noticable) loss in quality, but re-encoding to mpeg-2 is going to give some loss, no matter what settings you choose.

Doesn't matter which codec is used (DivX, Xvid, MS V3), the horizontal lines still show up in the video. It's really noticable when a person is moving fast. I am giving my personal experiences, not from reading an article at anandtech.

[sub]

When people mention horizontal lines, they are often experiencing deinterlacing issues. See http://www.dscaler.com/screenshots/index.htm for a screenshot. Is this what you're talking about?

[Raffka]

When people mention horizontal lines, they are often experiencing deinterlacing issues. See http://www.dscaler.com/screenshots/index.htm for a screenshot. Is this what you're talking about?

Yes, that's exactly it!

[sub]

I dont really do any re-encoding myself, so cant help you with your problem, but at least you now know whats causing the problem, and have some good keyworks (interlacing / deinterlacing) for googling for a solution.