I will upload an ass file made with mkvextract from a sample uploaded to demonstrate vlc ticket 8147.
The ass file works fine with (mplayer and) -vf ass but cannot be opened by -vf subtitles because it contains "Comment" events.
$ ffmpeg -f lavfi -i testsrc -vf "subtitles=\[sage\]_Bakuman_S3_-_18_\[720p\]\[9689D178\].ass" -qscale 2 -t 30 out.avi
ffmpeg version N-49841-ga63dc84 Copyright (c) 2000-2013 the FFmpeg developers
built on Feb 12 2013 16:33:13 with gcc 4.7 (SUSE Linux)
configuration: --enable-gpl --disable-indev=jack --enable-libmp3lame --enable-libass
libavutil 52. 17.101 / 52. 17.101
libavcodec 54. 91.102 / 54. 91.102
libavformat 54. 62.100 / 54. 62.100
libavdevice 54. 3.103 / 54. 3.103
libavfilter 3. 37.101 / 3. 37.101
libswscale 2. 2.100 / 2. 2.100
libswresample 0. 17.102 / 0. 17.102
libpostproc 52. 2.100 / 52. 2.100
[lavfi @ 0x2518000] Estimating duration from bitrate, this may be inaccurate
Input #0, lavfi, from 'testsrc':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 320x240 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
Please use -q:a or -q:v, -qscale is ambiguous
[ass @ 0x252f280] Estimating duration from bitrate, this may be inaccurate
[AVFilterGraph @ 0x24fc460] Error initializing filter 'subtitles' with args '[sage]_Bakuman_S3_-_18_[720p][9689D178].ass'
Error opening filters!
$ ffmpeg -f lavfi -i testsrc -vf "ass=\[sage\]_Bakuman_S3_-_18_\[720p\]\[9689D178\].ass" -qscale 2 -t 30 out.avi
ffmpeg version N-49841-ga63dc84 Copyright (c) 2000-2013 the FFmpeg developers
built on Feb 12 2013 16:33:13 with gcc 4.7 (SUSE Linux)
configuration: --enable-gpl --disable-indev=jack --enable-libmp3lame --enable-libass
libavutil 52. 17.101 / 52. 17.101
libavcodec 54. 91.102 / 54. 91.102
libavformat 54. 62.100 / 54. 62.100
libavdevice 54. 3.103 / 54. 3.103
libavfilter 3. 37.101 / 3. 37.101
libswscale 2. 2.100 / 2. 2.100
libswresample 0. 17.102 / 0. 17.102
libpostproc 52. 2.100 / 52. 2.100
[lavfi @ 0x340d000] Estimating duration from bitrate, this may be inaccurate
Input #0, lavfi, from 'testsrc':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 320x240 [SAR 1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
Please use -q:a or -q:v, -qscale is ambiguous
[Parsed_ass_0 @ 0x3412900] [0x33f0da0]: Warning: no style named 'Sign' found, using 'Default'
[Parsed_ass_0 @ 0x3412900] Added subtitle file: '[sage]_Bakuman_S3_-_18_[720p][9689D178].ass' (24 styles, 1165 events)
Output #0, avi, to 'out.avi':
Metadata:
ISFT : Lavf54.62.100
Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 320x240 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 25 tbn, 25 tbc
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo -> mpeg4)
Press [q] to stop, [?] for help
[Parsed_ass_0 @ 0x3412900] fontconfig: Selected font is not the requested one: 'DejaVu Sans Bold' != 'PT Sans'
[Parsed_ass_0 @ 0x3412900] fontconfig: Selected font is not the requested one: 'DejaVu Sans' != 'Sketchbook Nasty'
[Parsed_ass_0 @ 0x3412900] fontconfig: Selected font is not the requested one: 'DejaVu Sans' != 'The Great Escape'
[Parsed_ass_0 @ 0x3412900] fontconfig: Selected font is not the requested one: 'DejaVu Sans Bold Oblique' != 'PT Sans'
frame= 750 fps=0.0 q=2.0 Lsize= 1734kB time=00:00:30.00 bitrate= 473.5kbits/s
video:1710kB audio:0kB subtitle:0 global headers:0kB muxing overhead 1.376683%
Encoding with -vf subtitles works fine if I remove all "Comment" events (or rename them to "Dialogue").
Fixed by Nicolas.