You need to reassign input (or use an intermediate variable). What's happening in each loop is you are taking the fresh input and drawing the text over that.

You could do something like

Copy...
        input = input.drawtext(
...

I believe, though I haven't worked with videos much. Like, you might need to do more to make sure the text doesn't all just layer over itself.

A colon ":" and a backslash "\" have special meaning when specifying the parameters for drawtext. So what you can do is to escape them by converting ":" to "\:" and "\" to "\\". Also you can enclose the path to your font file in single quotes incase the path contains spaces.

So you will have

ffmpeg -i C:\Test\rec\vid_1321909320.avi -vf drawtext=fontfile='C\:\\Windows\\Fonts\\arial.ttf':text=test vid_1321909320.flv

This is your basic template. I assume the input is 720p.

ffmpeg -i 720p_input -f lavfi -i "color=black@0:s=64x64,format=yuva420p" -filter_complex "[1]trim=end_frame=1,drawtext=font={font_family}:text={watermark_text}:fontcolor={font_color}:fontsize={font_size}{background_box}:{watermark_position},rotate=a={degree}*PI/180:ow=hypot(iw,ih):oh=ow:c=black@0,loop=-1:1:0,tile=15x9,trim=end_frame=1[wm];[0][wm]overlay=0:0" -c:a copy -preset encoding_preset ./watermark/{media_id}.mp4

{degree} should be replaced by rotation angle. The ultimate size of each text cell is 64 x sqrt(2) = 90 pixels on each side. 15x9 is the tiling layout. Adjust this to cover the full input frame.

Just chain the drawtext, at the end.

ffmpeg \
-i video1.mp4 -i video2.mp4
-filter_complex "[0:v:0] [0:a:0] [0:v:1] [0:a:1] concat=n=2:v=1:a=1 [v][a];
[v]drawtext=text='SOME TEXT':x=(w-text_w):y=(h-text_h):fontfile=OpenSans.ttf:fontsize=30:fontcolor=white[v]" \
-map "[v]" -map "[a]" -deinterlace \
-vcodec libx264 -pix_fmt yuv420p -preset $QUAL -r $FPS -g $(($FPS * 2)) -b:v $VBR \
-acodec libmp3lame -ar 44100 -threads 6 -qscale 3 -b:a 712000 -bufsize 512k \
-f flv "$YOUTUBE_URL/$KEY"

Positions

• Top left: x=0:y=0 (with 10 pixel padding x=10:y=10)
• Top center: x=(w-text_w)/2:y=0 (with 10 px padding x=(w-text_w)/2:y=10)
• Top right: x=w-tw:y=0 (with 10 px padding: x=w-tw-10:y=10)
• Centered: x=(w-text_w)/2:y=(h-text_h)/2
• Bottom left: x=0:y=h-th (with 10 px padding: x=10:y=h-th-10)
• Bottom center: x=(w-text_w)/2:y=h-th (with 10 px padding: x=(w-text_w)/2:y=h-th-10)
• Bottom right: x=w-tw:y=h-th (with 10 px padding: x=w-tw-10:y=h-th-10)

Full example (centered)

ffmpeg -i input.mp4 -vf "drawtext=text='Super User':x=(w-text_w)/2:y=(h-text_h)/2:fontsize=24:fontcolor=white" -c:a copy output.mp4

See drawtext filter documentation for more info.

Use drawbox for the box, and drawtext for the text.

ffmpeg -i input.mp4 -vf \
"format=yuv444p, \
 drawbox=y=ih/PHI:[email protected]:width=iw:height=48:t=fill, \
 drawtext=fontfile=OpenSans-Regular.ttf:text='Title of this Video':fontcolor=white:fontsize=24:x=(w-tw)/2:y=(h/PHI)+th, \
 format=yuv420p" \
-c:v libx264 -c:a copy -movflags +faststart output.mp4

• drawtext has a box option, but as far as I can tell it can't be an arbitrary width and is relative to the text size, so that is why drawbox is used instead.

• The format filter is used to improve the color of the drawbox area; otherwise, depending on your input and output formats, the area could look de-saturated or monochrome. The format filter is then used again to ensure that the pixel format of the output file is compatible with all players.

• The audio is being stream copied in this example because you may not want to needlessly re-encode it.

• Old ffmpeg users will have to use t=max instead of t=fill.