title: correctly escaping text in drawtext filter
body: <p>According to documentation <code>%{}:,</code> should be escaped with slash. But when I escape <code>%</code> the text is not added. There's error message saying <code>Stray % near ')'</code>.  But what does it mean and how I can fix it? Command and output:</p>
  
  <pre><code>$ /usr/bin/ffmpeg -y -i /home/www/255871.mov -af 'aresample=async=1:min_hard_comp=0.100000' -vf 'scale=480:trunc(ow/a/2)*2,transpose=1 [in];movie=watermarks/text-box440.mov,scale=320:55 [bg];[in][bg] overlay=x=20:y=main_h-80,drawtext=fontsize=20:fix_bounds=1:fontfile=Helvetica\\:Style=bold:fontcolor=0xe6b300:text=small kitten \%\):x=30:y=h-80+ascent/2:draw=gte(t\,0)\;lt(t\,5) [out]' -pix_fmt yuv420p -r 24.39 -map_metadata -1 -movflags +faststart -f mp4 -vcodec libx264 -b:v 800k -maxrate 1100k -bufsize 2M -bt 256k -profile:vbaseline -acodec libfdk_aac -ab 64k -ar 44100 -ac 1 /tmp/kitten.mp4
  ffmpeg version 1.2 Copyright (c) 2000-2013 the FFmpeg developers
    built on Mar 15 2013 18:40:14 with gcc 4.4.6 (GCC) 20120305 (Red Hat 4.4.6-4)
    configuration: --enable-gpl --enable-libmp3lame --enable-libvo-aacenc --enable-libx264 --enable-version3 --enable-pthreads --enable-libfaac --enable-nonfree --enable-libfdk_a
  ac --enable-fontconfig --enable-libfreetype
    libavutil      52. 18.100 / 52. 18.100
    libavcodec     54. 92.100 / 54. 92.100
    libavformat    54. 63.104 / 54. 63.104
    libavdevice    54.  3.103 / 54.  3.103
    libavfilter     3. 42.103 /  3. 42.103
    libswscale      2.  2.100 /  2.  2.100
    libswresample   0. 17.102 /  0. 17.102
    libpostproc    52.  2.100 / 52.  2.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/www/255871.mov':
    Metadata:
      major_brand     : qt
      minor_version   : 0
      compatible_brands: qt
      creation_time   : 2012-07-17 07:42:35
      model           : iPhone 3GS
      model-rus       : iPhone 3GS
      encoder         : 4.2.1
      encoder-rus     : 4.2.1
      date            : 2012-07-17T10:42:35+0300
      date-rus        : 2012-07-17T10:42:35+0300
      make            : Apple
      make-rus        : Apple
    Duration: 00:00:09.38, start: 0.000000, bitrate: 790 kb/s
      Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p, 480x360, 720 kb/s, 29.97 fps, 29.97 tbr, 600 tbn, 1200 tbc
      Metadata:
        rotate          : 90
        creation_time   : 2012-07-17 07:42:35
        handler_name    : Core Media Data Handler
      Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s
      Metadata:
        creation_time   : 2012-07-17 07:42:35
        handler_name    : Core Media Data Handler
  [Parsed_drawtext_5 @ 0x2ae9b00] Using "/usr/share/fonts/default/Type1/n019003l.pfb"
  [libx264 @ 0x2ae7d40] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  [libx264 @ 0x2ae7d40] profile Constrained Baseline, level 2.1
  [libx264 @ 0x2ae7d40] 264 - core 130 r2274 c832fe9 - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=0 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=24 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=abr mbtree=1 bitrate=800 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=1100 vbv_bufsize=2000 nal_hrd=none ip_ratio=1.40 aq=1:1.00
  Output #0, mp4, to '/tmp/kitten.mp4':
    Metadata:
      encoder         : Lavf54.63.104
      Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 360x480, q=-1--1, 800 kb/s, 19512 tbn, 24.39 tbc
      Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 44100 Hz, mono, s16, 64 kb/s
  Stream mapping:
    Stream #0:0 -&gt; #0:0 (h264 -&gt; libx264)
    Stream #0:1 -&gt; #0:1 (aac -&gt; libfdk_aac)
  Press [q] to stop, [?] for help
  [Parsed_drawtext_5 @ 0x2ae9b00] Stray % near ')'
      Last message repeated 201 times
  Stray % near ')'0.0 q=27.0 size=     480kB time=00:00:07.96 bitrate= 493.4kbits/s dup=0 drop=35
  [Parsed_drawtext_5 @ 0x2ae9b00] Stray % near ')'
      Last message repeated 77 times
  Starting second pass: moving header on top of the file
  frame=  231 fps=0.0 q=-1.0 Lsize=    1002kB time=00:00:09.47 bitrate= 866.6kbits/s dup=0 drop=50
  video:921kB audio:74kB subtitle:0 global headers:0kB muxing overhead 0.680957%
  [libx264 @ 0x2ae7d40] frame I:1     Avg QP:24.43  size: 13264
  [libx264 @ 0x2ae7d40] frame P:230   Avg QP:23.72  size:  4041
  [libx264 @ 0x2ae7d40] mb I  I16..4: 24.8%  0.0% 75.2%
  [libx264 @ 0x2ae7d40] mb P  I16..4:  2.3%  0.0%  4.8%  P16..4: 34.4% 28.8%  9.4%  0.0%  0.0%    skip:20.3%
  [libx264 @ 0x2ae7d40] coded y,uvDC,uvAC intra: 62.5% 54.2% 4.4% inter: 19.6% 20.3% 0.1%
  [libx264 @ 0x2ae7d40] i16 v,h,dc,p: 36% 29% 19% 16%
  [libx264 @ 0x2ae7d40] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 19% 21% 20%  6%  8%  7%  7%  6%  6%
  [libx264 @ 0x2ae7d40] i8c dc,h,v,p: 65% 15% 17%  3%
  [libx264 @ 0x2ae7d40] ref P L0: 93.4%  4.3%  2.3%
  [libx264 @ 0x2ae7d40] kb/s:796.32
  </code></pre>