我试图使用ffmpeg从带有字幕的视频中提取单个帧。
我自己建了ffmpeg：
sircmpwn@picard ~/sources/bakabt-staging/hennkeo/groups $ ffmpeg
ffmpeg version N-54036-g6c4516d Copyright (c) 2000-2013 the FFmpeg developers
built on Jun 15 2013 11:56:01 with gcc 4.7 (Ubuntu/Linaro 4.7.3-1ubuntu1)
configuration: --prefix=/home/sircmpwn/ffmpeg_build --extra-cflags=-I/home/sircmpwn/ffmpeg_build/include --extra-ldflags=-L/home/sircmpwn/ffmpeg_build/lib --bindir=/home/sircmpwn/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
libavutil 52. 35.101 / 52. 35.101
libavcodec 55. 16.100 / 55. 16.100
libavformat 55. 8.102 / 55. 8.102
libavdevice 55. 2.100 / 55. 2.100
libavfilter 3. 77.101 / 3. 77.101
libswscale 2. 3.100 / 2. 3.100
libswresample 0. 17.102 / 0. 17.102
libpostproc 52. 3.100 / 52. 3.100
Hyper fast Audio and Video encoder
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...
Use -h to get full help or, even better, run 'man ffmpeg'
我运行这个：
sircmpwn@picard ~/sources/bakabt-staging/hennkeo/groups $ ffmpeg -ss 00:09:18 -i horrible.mkv -sn -vf ass=horrible.ass -t 1 -vframes 1 horrible-1.png
ffmpeg version N-54036-g6c4516d Copyright (c) 2000-2013 the FFmpeg developers
built on Jun 15 2013 11:56:01 with gcc 4.7 (Ubuntu/Linaro 4.7.3-1ubuntu1)
configuration: --prefix=/home/sircmpwn/ffmpeg_build --extra-cflags=-I/home/sircmpwn/ffmpeg_build/include --extra-ldflags=-L/home/sircmpwn/ffmpeg_build/lib --bindir=/home/sircmpwn/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-nonfree --enable-x11grab
libavutil 52. 35.101 / 52. 35.101
libavcodec 55. 16.100 / 55. 16.100
libavformat 55. 8.102 / 55. 8.102
libavdevice 55. 2.100 / 55. 2.100
libavfilter 3. 77.101 / 3. 77.101
libswscale 2. 3.100 / 2. 3.100
libswresample 0. 17.102 / 0. 17.102
libpostproc 52. 3.100 / 52. 3.100
Input #0, matroska,webm, from 'horrible.mkv':
Metadata:
creation_time : 2013-05-26 13:34:41
Duration: 00:23:42.11, start: 0.000000, bitrate: 1900 kb/s
Stream #0:0: Video: h264 (High), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 30.30 fps, 30.30 tbr, 1k tbn, 59.94 tbc (default) (forced)
Stream #0:1: Audio: aac, 44100 Hz, stereo, fltp (default) (forced)
Stream #0:2: Subtitle: ssa (default) (forced)
Codec 0x18000 is not in the full list.
Stream #0:3: Attachment: unknown_codec
Metadata:
filename : OpenSans-Semibold.ttf
mimetype : application/x-truetype-font
[Parsed_ass_0 @ 0x3521780] Added subtitle file: 'horrible.ass' (9 styles, 374 events)
Output #0, image2, to 'horrible-1.png':
Metadata:
encoder : Lavf55.8.102
Stream #0:0: Video: png, rgb24, 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 90k tbn, 30.30 tbc (default) (forced)
Stream mapping:
Stream #0:0 -> #0:0 (h264 -> png)
Press [q] to stop, [?] for help
frame= 1 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.03 bitrate=N/A dup=0 drop=57
video:364kB audio:0kB subtitle:0 global headers:0kB muxing overhead -100.005907%