Transcoding(mpeg2 HD to mpeg2 HD) while adding a logo

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maitrepiet
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Transcoding(mpeg2 HD to mpeg2 HD) while adding a logo

Postby maitrepiet » 12 Jul 2010 11:02

Here's what I try to do:

I have a high definition video camera, connected to the PC through IEEE1394. Bitrate from the camera is about 25Mbs
I want to capture the videostream and add a logo to it at a certain point. (I do this through the RC interface, but probably not relevant in this discussion)
If I use this commandline
vlc --logo-file logo.png dshow:// --dshow-adev=none --dshow-vdev="Microsoft AV/C Tape Subunit Device" --sout "#transcode{vcodec=mp2v,vb=12000,sfilter=logo}:std{access=file,mux=ps,dst=videoref.mpg}

the logo mechnism works fine, but when I move the camera, the video quality gets unaccaptable. Increasing the video bitrate does not seem to help.

If I use this command line:
vlc --logo-file logo.png dshow:// --dshow-adev=none --dshow-vdev="Microsoft AV/C Tape Subunit Device" --sout "#transcode{sfilter=logo}:std{access=file,mux=ps,dst=videoref.mpg}

The video is perfect, even with fast camera movement, but now the logo mechanism does not work anymore.
I hoped that this command would simply take the incoming video stream, add the logo overlay to it and re-encode.


The only difference between the 2 command lines is that in the second I don't specify the video encoder for the transcoding, nor the bitrate.
As soon as I specify any of the 2 (bitrate or codec) things go wrong.

I'm using vlc-1.1.0 compiled on june 21. My machine is a windows XP laptop, Intel Core Duo at 2.4 Ghz, 3 Gig Ram; Videocard: Ati mobility Radeon HD 3650 (512 MB)


Can someone help me out here. Are there any hardware acceleration settings I can enable?

Rémi Denis-Courmont
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Re: Transcoding(mpeg2 HD to mpeg2 HD) while adding a logo

Postby Rémi Denis-Courmont » 12 Jul 2010 17:44

Motion compensation does not work so well when the camera moves. So you either need more CPU and output bandwidth, or you get crappy quality. I don't think that's really avoidable.
Rémi Denis-Courmont
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