[MPlayer-users] documentation mencoder section multiple jpg / png / tga

[Guillaume POIRIER]

Hi Helmut,

On 11/30/05, Helmut Rathgen <helmut.rathgen at web.de> wrote:
> Hello Guillaume,
>
> thank you for your answer! I understand you are the one who is taking
> care about the docs?!

Yes, I'm the current maintainer of MEncoder's docs.


> Really nice - they are great!

Thanks! I don't think I ever heared this since I contribute to
MPlayer. Most users who post to the mailing list complain that the doc
is too "high level" (which on the one hand I think is true, on the
other hand it has the benefit not to treat the user as if he was
stupid).


> I want to try to give you more information.
>
> >problem. Helmut, what version of MPlayer are you using? Are you using
> >CVS or a release? Try with latest CVS if you did not try already.
> >
> I am using 1.0pre7try2.

Please, try with CVS version of MPlayer: pre7 is now fairly dated, and
I would not be surprised if the problem you experience is fixed in
CVS.


> I started from a set of .tif files. Converted them to .jpg.
>
> *|$> for i in *.tif; do convert -depth 8 -colorspace rgb $i `basename $i .tif`.jpg; done|

[..]

> ==========================================================================
> Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
> INFO: libavcodec init OK!
> Selected video codec: [ffmjpeg] vfm:ffmpeg (FFmpeg MJPEG decoder)
> ==========================================================================
> Audio: no sound
> Freeing 0 unused audio chunks.
> Starting playback...
> [ffmpeg] aspect_ratio: nan
> VDec: vo config request - 680 x 512 (preferred csp: Unknown)
> Trying filter chain: vo
> Could not find matching colorspace - retrying with -vf scale...
> Opening video filter: [scale]
> SwScale params: -1 x -1 (-1=no scaling)
> Trying filter chain: scale vo
> The selected video_out device is incompatible with this codec.
> mp_image: Unknown out_fmt: 0x0
> *** [vo] Exporting mp_image_t, 680x512x0bpp YUV packed, 0 bytes
>
> FATAL: Could not initialize video filters (-vf) or video output (-vo).
>
> uninit video: ffmpeg
> vo: uninit ...
>
> Exiting... (End of file)
>
> *...the movies doesn't play.

Ok... My guess is that ffmpeg's MJPEG decoder is somewhat broken or
incorrectly initialised. That's a quite different problem than just
updating docs.
Please try if the problem still exists in CVS version or not (just
follow the instructions listed on the link I gave you earlier).

If the problem still exist, then either report the problem here or
open a bugzilla report: http://bugzilla.mplayerhq.hu



[..]

> I understand without -vc ijpg mplayer chooses lavc's ffmpeg to play the "mf://*.jpg" source. However ijpg is the better choice.
>
> Now as for the mencoder, I understand it works "in two steps". Correct me if I'm wrong. First mplayer generates a stream of the source and second this stream is fed to mencoder which generates the desired output file. So I can use the -vc option with mencoder to tell it how it should read the source, like

That's not technically correct, but that's a somewhat good approximation ^^

[..]


> So I suggest it should be very useful for a newbee (like me) to understand from the examples in the mencoder mjpg / mpng / mtga Docs section that this is possible (and maybe sometimes necessary).

I'll see what I can do. If the doc has to be updated to work around a
bug that can't be fixed right now, I may add a new FAQ entry.
I could also add a note to MEncoder's docs to point out that in some
cases it my be desirable to force the input codec with "-vc".

But before I do that, please test CVS.

Guillaume

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