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List:       mjpeg-users
Subject:    Re: [Mjpeg-users] Good intermediate format to use
From:       Mark Heath <mjpeg0 () silicontrip ! org>
Date:       2009-01-24 2:11:03
Message-ID: C9BF0D86-9F47-4E75-ADE6-F186BFFF2F80 () silicontrip ! org
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On 23/01/2009, at 5:54 AM, Bernhard Praschinger wrote:

> The mjpegtools cannot create DV encoded files (at least I don't know
> how). They can only read them. The the best quality is a mjpeg encoded
> AVI/MOV at a high quality factor of 95. (100 might cause problems)


if you are wanting to use DV files as an intermediate format with the  
mjpeg (yuv) tools, I recommend ffmpeg

from memory the command would look something like this:

mjpegtoolchain | ffmpeg -f yuv4mpegpipe -i - -vcodec dvvideo file.dv

FFmpeg determines the destination format based on the file extension.

>
> Well If you really want every bit of quality you can create single raw
> ppm files. I would not recommend that.

Nor would I because ppm would be in RGB without chroma subsampling.   
So you would be colour space converting and chroma upsampling.  This  
would result in loss of colour gamut (probably minimal) and a larger  
file than needed.

You could use the raw yuv stream, that are produced by mjpegtools.

However there are plenty of open source lossless codecs that would be  
better.  I think huffyuv is one, which ffmpeg supports.  There is even  
a zlib codec.

You could use use the mjpeg codec with ffmpeg, there is a -sameq  
option to ffmpeg, which (i believe) turns off the jpeg quantisation,  
so retains all the quality.  Sometimes this has been useful if the  
source had already been compressed, only produces a file size based on  
the quality of the original.  I have found that it produces smaller  
files depending on the compression of the original file.  Though it  
will produce very large files if the source is noisey and from a high  
bitrate source.

I would highly recommend using ffmpeg in your mjpegtool chain, it can  
convert to a large number of file formats and codecs.

Mark

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