[MPlayer-dev-eng] using mencoder to make movie of graphics visualization frames.

[Ivo]

Hi,

On Tuesday 16 August 2005 02:28, don fisher wrote:
> I attempted using the conversion to png. For some reason, my 64bit
> Opteron version of mencoder
> (mplayer-1.0-0.15.pre6a.1.fc3.rf.x86-64.rpm)
> segfaults with png. I was able to do the decoding on my 32 bit laptop
> without problems. In this damn litigious society it is always hard to
> find the rpm's with all of the codecs in them.

Always use the latest version of MPlayer, preferably CVS, when reporting 
bugs. This could be a bug in MPlayer, but might as well be a bug in libpng.
Also, bugreports should go to the mplayer-users mailinglist.

> I would prefer to use a raw rather that compressed format if possible.
> It takes about 4 times as long to convert from tiff to png than it
> does to make the movie using "high quality", non real time parameters.
> As you know, any of these lossless entropy based encoders are slow,
> especially if they are adaptive.
>
> My data files are 1024x1024 pixels, and the tiff tiles are 3148650
> bytes long. 3148650 - 3*1024*1024 = 2922 bytes for Tiff color maps
> etc. So I am assuming the data is in raw format plus the header. I
> inquired about the SGI format since it is also basically raw, but big
> endian. I thought TGA could represent data in raw format, but no
> conversion was mentioned. (My disk space is cheap!).
>
> Under section 3.1, Selecting codecs & format, it includes raw as one
> of the options. Is there an example of how this would be implemented?
>   I assume the image parameters would be included under type, but
> inclusion of the color maps is not obvious.
>
> The more I look into Tiff, the worse it gets. It can be simple, but
> the general case can really get ugly:-)

At first, keep it simple. I'm no TIFF expert, but IIRC you can put almost 
anything in TIFF, including LZW or JPEG compressed images. If you implement 
a TIFF decoder for MPlayer, just support raw 24-bit TIFF only. If somebody 
needs <your-favorite-compression-scheme>-TIFF support, he or she can add 
that later.

For an example implementation of reading a tiff file, you could read the 
source of tifftopnm, though they read a lot more varients of TIFF (but by 
no means every flavour; see man tifftopnm), or google around a bit.

Conversion to TGA can be done similar to conversion to PNG:

convert foo.tiff bar.tga			or
tifftopnm foo.tiff | ppmtotga -rgb > bar.tga

BTW the 2922 bytes you mention is probably just an overly bloated TIFF 
header. I don't see how a true color 24-bit image can have a color map 
(except when it maps to a much larger colorspace, but I think that's 
unlikely and 2922 bytes won't be enought space then).

BTW2 please don't top post!

--Ivo