[MEncoder-users] DVD to VCD Convertion

[Ron Wills]

RC wrote:

>On Fri, 22 Jul 2005 18:37:14 -0600
>Ron Wills <ron at rwsoft.ca> wrote:
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>>can't seem to get the stereo channels reduced to mono. 
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>-channels 1 has always worked for me.  If it isn't working for you, at
>least post the exact mencoder command-line you are using.  These
>problems are all too often caused by an space, dash, etc.
>  
>
Sorry, these are in a script to handle vcd, svcd, pal and ntsc. This is 
the first pass to pull out the audio for VCD PAL:

mencoder -oac lavc -ovc frameno -vf scale=352:288,harddup  -srate 44100 
-channels 1 -af lavcresample=44100 -lavcopts acodec=mp2:abitrate=128 
-ofps 25  dvd://1 -o frameno.avi

or

mencoder -oac lavc -ovc frameno -vf scale=352:288,harddup  -srate 44100
-af lavcresample=44100 -lavcopts acodec=mp2:abitrate=128:amode=0 -ofps 25 
dvd://1 -o frameno.avi

When I run this I'm getting from mencoder:
 AUDIO: 48000 Hz, 1 ch, 16 bit (0x10), ratio: 56000->96000 (448.0 kbit)
 Building audio filter chain for 48000Hz/1ch/16bit -> 44100Hz/1ch/16bit

The mplayer frameno.avi:
  AUDIO: 44100 Hz, 2 ch, 16 bit (0x10), ratio: 16000->176400 (128.0 kbit)

>Unless my memory is fuzzy, VCD doesn't support mono anyhow, it requires
>two audio channels.  With SVCDs, you can have mono audio, and you can
>use much lower bitrates, giving you a lot more room for video.
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I wasn't sure of this myself, but it seems to be handling the drop in 
bitrates with out a problem.

  VCD PAL specs: audio bit rate of 224 and video bit rate of 1152
  And is handling: audio bit rate of 128 and video bit rate of 635

So, I've decided to push my luck by using mono ;)

>>AUDIO: 44100 Hz, 2 ch, 16 bit (0x10), ratio: 16000->176400 (128.0
>>kbit)
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>Yep, that's 2 channels.
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>>and try to reduce the amount of flicker in the VCDs. 
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>Flicker?
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  Mostly a the beginning of the VCD. About every second I'm getting 
frames that are heavily pixelated, which are causing a flicker in the 
movie. I'm hoping by reducing the audio a bit more, will help reduce the 
pixelation on these frames (a bit higher bitrate for the video)... but 
then again this is also going beyond my understand of mpg encoding.

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