mosaic alignment

[jesus_]

The mosaic generated by vlc 0.8.6d looks like this:



but I would want it to look like this, with the video's centered in their container:



This is the command I'm using:

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vlc -I telnet --ttl 12 --fake-aspect-ratio "16:9" --vlm-conf mosaic.conf --fake-file mosaic.jpg

with this conf:

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# reset VLM configuration del all # Background options new bg broadcast enabled setup bg input fake: setup bg output #transcode{acodec=mpga,ab=128,vcodec=mpgv,vb=4096,scale=1,sfilter=mosaic}:bridge-in:std{access=udp{ttl=5},mux=ts,dst=225.1.1.1:2000} # Mosaic options setup bg option mosaic-height=932 setup bg option mosaic-width=1526 setup bg option mosaic-xoffset=235 setup bg option mosaic-yoffset=103 setup bg option mosaic-position=1 setup bg option mosaic-rows=3 setup bg option mosaic-cols=4 setup bg option mosaic-order=een,two,[...] setup bg option mosaic-keep-picture new one broadcast enabled setup one input "udp://192.168.1.1@224.1.1.1:2000" setup one output #duplicate{dst=mosaic-bridge{id=one,width=360},select=video,dst=bridge-out{id=one}} new two broadcast enabled setup two input "udp://192.168.1.1@224.1.1.2:2000" setup two output #duplicate{dst=mosaic-bridge{id=two,width=360},select=video,dst=bridge-out{id=two}} [...] control bg play control one play control two play [...]

From the wiki:

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* mosaic-align <integer> : Alignment of the mosaic in the parent video. default value: 5

(http://wiki.videolan.org/Documentation:Modules/mosaic)

That's not the problem, it's aligned ok in the global video, it's the internal aligning I want to change.

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* mosaic-position <integer> : Positioning method of the mosaic elements. Use 0 to position the elements automatically on the grid, 1 to position the elements in fixed positions on the grid (see mosaic-order) and 2 to use grid independant offsets (see mosaic-offsets).. default value: 0

Is set to 1, since I want to decide in what order the images get on the grid.

I browsed through the source to find out where the positioning is taking place. I figured that somehow, the images were not aligned right inside their bounding box in the vertical direction. I found following code-snippet in mosaic.c:

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if( fmt_out.i_width > col_inner_width || p_sys->b_ar || p_sys->b_keep ) { /* we don't have to center the video since it takes the whole rectangle area or it's larger than the rectangle */ p_region->i_x = p_sys->i_xoffset + i_col * ( p_sys->i_width / p_sys->i_cols ) + ( i_col * p_sys->i_borderw ) / p_sys->i_cols; } else { /* center the video in the dedicated rectangle */ p_region->i_x = p_sys->i_xoffset + i_col * ( p_sys->i_width / p_sys->i_cols ) + ( i_col * p_sys->i_borderw ) / p_sys->i_cols + ( col_inner_width - fmt_out.i_width ) / 2; }

Sounds logic, if the image is wider than the containerm don't center. However, for the vertical alignment I found:

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if( fmt_out.i_height < row_inner_height || p_sys->b_ar || p_sys->b_keep ) { /* we don't have to center the video since it takes the whole rectangle area or it's taller than the rectangle */ p_region->i_y = p_sys->i_yoffset + i_row * ( p_sys->i_height / p_sys->i_rows ) + ( i_row * p_sys->i_borderh ) / p_sys->i_rows; } else { /* center the video in the dedicated rectangle */ p_region->i_y = p_sys->i_yoffset + i_row * ( p_sys->i_height / p_sys->i_rows ) + ( i_row * p_sys->i_borderh ) / p_sys->i_rows + ( row_inner_height - fmt_out.i_height ) / 2; }

First of all, the <, shouldn't that be >? The first block gets executed if the image is smaller than the container, while the comments show that it should be executed when it's larger. I tried to change it and compiled, but the behaviour did not change. p_sys->b_ar || p_sys->b_keep make sure that the images never get centered vertically if mosaic-keep-picture or mosaic-keep-aspect-ratio is enabled. Could someone explain why the image shouldn't be centered in that case? I'm missing the logic. I'm going to change the code and recompile so that the images are always centered, but I would like to understand why this is coded the way it is, there must be a reason. (God knows what will happen after my recompile :p)

Any hints an thoughts are appreciated.

[jesus_]

I changed the code into this:

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// if( fmt_out.i_height < row_inner_height // || p_sys->b_ar || p_sys->b_keep ) // { // /* we don't have to center the video since it takes the // whole rectangle area or it's taller than the rectangle */ // p_region->i_y = p_sys->i_yoffset // + i_row * ( p_sys->i_height / p_sys->i_rows ) // + ( i_row * p_sys->i_borderh ) / p_sys->i_rows; // } // else // { /* center the video in the dedicated rectangle */ p_region->i_y = p_sys->i_yoffset + i_row * ( p_sys->i_height / p_sys->i_rows ) + ( i_row * p_sys->i_borderh ) / p_sys->i_rows + ( row_inner_height - fmt_out.i_height ) / 2; // }

Very simple hack, but it does seem to do the trick. Everything still works, and my 16:9 images are aligned in the center vertically.

[Jean-Baptiste Kempf]

I don't think this is the good way to do it.

Anyway, send PATCHES to vlc-devel@ mailing list

[jesus_]

I agree That's why I won't submit a patch, it's a hack that does exactly what I want, but it's probably bugged for general purpose mosaic.