Subject: [mythtv-users] Changing bitrate with avidemux2

papenfuss at papenfuss at
Sat Mar 20 10:49:53 EST 2004

On Fri, 19 Mar 2004, Gregory J. McGee wrote:

> Use svcd/2 pass for best results, you also set your output size,although
> it tends to run a hair "large".
> avidemux-2.0.22 (possibly earlier) can also dump mpegPS aka vobs, as
> well as load mythtv nuvs directly, (mpeg4 OR rtjpeg) then import into
> vobcopy and dump to iso with an "i" keypress.

	You may want to look at my previous postings on this.  The mpegPS out
of avidemux2 was *significantly* larger (20%) than the output of tcmplex or
mplex-ing the video and audio together.  I don't know which one is right, but
the avidemux stream has a lot more padding stream pieces.

> >Subject: [mythtv-users] Changing bitrate with avidemux2
> >To: Discussion about mythtv <mythtv-users at>
> >Message-ID: <200403191113.44352.jcaputo1 at>
> >Content-Type: text/plain;  charset="us-ascii"
> >I know there are some folks out there that use avidemux2 to manipulate 
> >their MPEG-2 recordings... I have a quick question:
> >I've been using nuvexport to transcode my 480x480 RTjpeg recordings to 
> SVCD.  It's worked well.  Now I have an M-179, and want to make an 
> SVCD.  My recording profile is set to 480x480, and I've already used 
> avidemux2 to cut the commercials (on keyframe boundaries).  Now I need 
> to turn down the bitrate to something in the SVCD range.  The question 
> is, exactly how do I do this in avidemux2?  I looked at the Video Codec 
> options, and there was an SVCD preset.  However, I have to choose 
> between setting the bitrate or setting the quantization.  Which do I 
> want?  Is one faster, or will one give better results?
> Hopefully I'll only need to do this on a few recordings, as I'm changing
> my profile to record at 1/2 D1 so I can burn CVDs instead of SVCDs.
	I understand the quandary of which to record at.  It sorta depends on 
what the target will be.  I've run some sampling tests with a PVR250, and there 
is a bit of quality drop in recording with 352 instead of 480.  I think that 
recording a "master-quality" mpeg at something larger and then reencoding 
(2-pass) at a lower rate will produce better quality in the end.  
Unfortunately, it sorta negates the best reason for the hardware mpeg card.  
SOL no matter what you do, I guess... :)


* The prime directive of Linux:  					*
* 	- learn what you don't know, 					*
* 	- teach what you do.						*
* 						(Just my 20 USm$)	*

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