Cut editing Mpeg2 files

Fredv wrote on 11/10/2008, 11:34 AM
A question for those of you that know about the Mpeg stream.

I'm recording off air broadcasts using a Hauppauge, WinTV-PVR-350. I'm using the setting of Mpeg2, 12 mbps, variable bit rate with the average of 9600, peak of 12, 15 GOP, 720x480. These are normal SD broadcasts I'm recording over the air of our newscasts.

The original thought was to take the file that PVR-350 creates, edit it on Vegas, and render it out to my DVD burner.

But I was reading some past posts on the Sony forum about why not to do this. The author(s) suggested I would be decoding and then re-encoding the video where it could get artifacts. I would like the final product to look as good as possible, so this concerns me.

It occurs to me, could I take the file from the PVR-350, open it in Sound Forge, do my cut edits, and then save the same file? Would that be better, or is there a way in Vegas to take a Mpeg2 in, edit, and then save it without quality loss.

Fred

Comments

rs170a wrote on 11/10/2008, 11:38 AM
Get Womble or VideoReDo as they're designed to edit MPEG-2 streams - and the recompress is loseless.

Mike
bStro wrote on 11/10/2008, 1:04 PM
If you are using Vegas 8, you may be able to do cuts without having to re-encode. Your render (encode) settings have to be exactly that of your source files. There's a chance you may need to change your recording settings to constant bitrate, though. Do a search of the forum for "vegas 8 mpeg smart render" for more details.

Also, if your intent is to produce DVDs (and not Blu-ray or HD-DVD discs), you will have to lower your bitrate. The max bitrate for a DVD is 9.8Mbps -- higher than that is against the DVD specs, and DVD Architect would just re-encode your file anyhow with a lower bitrate. And even 9.8Mbs is overkill. Better off using no more than 8Mbps. Most DVD players have a hard time keeping up with burned media with high bitrates, which will result in your disc stuttering.

Rob
Fredv wrote on 11/15/2008, 7:53 AM
Rob,

Is there a way to look at the source files, and copy down the attributes so that I can set the render to exactly the same settings?

It is for DVD. The WinTV capture is set for "Broadcast" which I *think* in their spec is 12 mbps.
blink3times wrote on 11/15/2008, 8:54 AM
I have winTV 350 (as well as a few others).

You can customize the win TV mpeg record settings. Go to the menu and click on CONFIGURE then click on MPEG SETTINGS, then click on ADVANCED this will open a VIDEO/AUDIO settings tab where you can view the bitrates being recorded as per setting and you can also customize your own record template.

I like to record at 7000 CBR (not VBR). Most of the time this will not required re-encoding at all depending of course what you do on the time line.
UlfLaursen wrote on 11/15/2008, 10:06 AM
Hi

I think you got some software with the PVR card to make cuts in the MPEG files - I had it together with my PVR 250 too.

I have edited a lot of recordings with my PVR 250 when I had it installed, on my Vegas 7, but mostly for web delivery, but I have reencoded for DVD too, without problems.

/Ulf
Fredv wrote on 11/15/2008, 11:37 AM
QUOTE: I like to record at 7000 CBR (not VBR). Most of the time this will not required re-encoding at all depending of course what you do on the time line.


I'll try changing the settings tonight and see how 700 CBR looks tonight. All I'm doing is straight cuts. I'm recording our station's newscast, clipping the commercials out, then rendering the completed portion to a DVD. I need it to be as good as possible in case the DVD is used to take a story off that is used later, or reedited.