我正在尝试使用命令从视频文件中提取关键帧：
ffmpeg -i newtape.mp4 -an -r 1 -y -vf "select='eq(pict_type,PICT_TYPE_I)'" -vsync 0 -ss 00:01:00 thumbnail_%09d.jpg
它启动了但很快就失败了：
ffmpeg version 0.7.13, Copyright (c) 2000-2011 the FFmpeg developers built on Sep 12 2012 14:54:45 with gcc 4.2.2 20070831 prerelease [FreeBSD] configuration: --prefix=/usr/local --mandir=/usr/local/man
--enable-shared --enable-gpl --enable-postproc --enable-avfilter --enable-pthreads --enable-memalign-hack --enable-runtime-cpudetect --cc=cc --extra-cflags='-I/usr/local/include/vorbis -I/usr/local/include' --ext ra-ldflags='-L/usr/local/lib ' --extra-libs=-pthread --disable-debug --enable-libaacplus --disable-indev=alsa --disable-outdev=alsa --disable-libopencore-amrnb --disable-libopencore-amrwb --disable-libcelt --disable-libdirac --disable-libfaac --disable-ffserver --enable-li bfreetype --enable-frei0r --disable-libgsm --enable-libmp3lame --enable-libopencv --disable-libopenjpeg --disable-librtmp --enable-libschroedinger --disable-ffplay --disable-libspeex --enable-libtheora --disable-vaapi --disable-vdpau --disable-libvo-aacenc --disable-libvo- amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-nonfree libavutil 50. 43. 0 / 50. 43. 0 libavcodec 52.123. 0 / 52.123. 0 libavformat 52.111. 0 / 52.111. 0 libavdevice 52. 5. 0 / 52.
5. 0 libavfilter 1. 80. 0 / 1. 80. 0 libswscale 0. 14. 1 / 0. 14. 1 libpostproc 51. 2. 0 / 51. 2. 0 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'newtape.mp4': Metadata:
major_brand : isom
minor_version : 512
compatible_brands: mp41
creation_time : 2012-10-14 12:44:32
encoder : Lavf51.12.1 Duration: 00:34:12.05, start: 0.000000, bitrate: 2653 kb/s
Stream #0.0(und): Video: h264 (Constrained Baseline), yuv420p, 960x540 [PAR 1:1 DAR 16:9], 2537 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc
Metadata:
creation_time : 2012-10-14 14:00:24
Stream #0.1(und): Audio: aac, 48000 Hz, stereo, s16, 110 kb/s
Metadata:
creation_time : 2012-10-14 14:00:24
Incompatible pixel format 'yuv420p' for codec 'mjpeg', auto-selecting format 'yuvj420p'
[buffer @ 0x805a24260] w:960 h:540 pixfmt:yuv420p tb:1/1000000 sar:1/1 sws_param:
[select @ 0x805a24340] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'Parsed filter 0 select'
[scale @ 0x805a243a0] w:960 h:540 fmt:yuv420p -> w:960 h:540 fmt:yuvj420p flags:0x4
Output #0, image2, to 'thumbnail_%09d.jpg':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: mp41
creation_time : 2012-10-14 12:44:32
encoder : Lavf52.111.0
Stream #0.0(und): Video: mjpeg, yuvj420p, 960x540 [PAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 90k tbn, 1 tbc
Metadata:
creation_time : 2012-10-14 14:00:24
Stream mapping:
Stream #0.0 -> #0.0
Press [q] to stop, [?] for help
[mjpeg @ 0x805a11420] Error, Invalid timestamp=0, last=000 bitrate= 0.0kbits/s
Video encoding failed
有什么方法可以防止这种情况发生，也许自动跳过一些片段？