我遇到从iPhone 4转换mov文件的问题。
运行此命令：
I, [2014-09-15T03:48:33.245231 #9676] INFO -- : Running transcoding...
ffmpeg -y -i /Users/lun/client/bookagoo/public/uploads/5405e9b0486f75a36c100000/video/1410727644xqxzdoxf-IMG_0040_1_.MOV -ss 5 -vframes 1 -f image2 /Users/lun/client/bookagoo/public/uploads/5405e9b0486f75a36c100000/video/1410727644xqxzdoxf-IMG_0040_1_-edited.jpg
E, [2014-09-15T03:48:33.321367 #9676] ERROR -- : Failed encoding...
ffmpeg -y -i /Users/lun/client/bookagoo/public/uploads/5405e9b0486f75a36c100000/video /1410727644xqxzdoxf-IMG_0040_1_.MOV -ss 5 -vframes 1 -f image2 /Users/lun/client/bookagoo/public/uploads/5405e9b0486f75a36c100000/video/1410727644xqxzdoxf-IMG_0040_1_-edited.jpg
我的ffmpeg给了我这样的错误：
FFMPEG::Error: Failed encoding.Errors: no output file created. Full output: ffmpeg version 2.3.1 Copyright (c) 2000-2014 the FFmpeg developers
built on Aug 20 2014 02:23:29 with Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
configuration: --prefix=/usr/local/Cellar/ffmpeg/2.3.1 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --enable-vda --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid --enable-libtheora --enable-libvorbis --enable-libvpx
libavutil 52. 92.100 / 52. 92.100
libavcodec 55. 69.100 / 55. 69.100
libavformat 55. 48.100 / 55. 48.100
libavdevice 55. 13.102 / 55. 13.102
libavfilter 4. 11.100 / 4. 11.100
libavresample 1. 3. 0 / 1. 3. 0
libswscale 2. 6.100 / 2. 6.100
libswresample 0. 19.100 / 0. 19.100
libpostproc 52. 3.100 / 52. 3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/lun/client/bookagoo/public/uploads/5405e9b0486f75a36c100000/video/1410641311nyv99k1j-IMG_0040_1_.MOV':
Metadata:
major_brand : qt
minor_version : 0
compatible_brands: qt
creation_time : 2014-07-20 09:47:08
model : iPhone 4
model-rus : iPhone 4
encoder : 7.0.4
encoder-rus : 7.0.4
date : 2014-07-20T13:47:08+0400
date-rus : 2014-07-20T13:47:08+0400
make : Apple
make-rus : Apple
Duration: 00:00:01.84, start: 0.000000, bitrate: 827 kb/s
Stream #0:0(und): Video: h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv, smpte170m), 480x360, 742 kb/s, 23.98 fps, 23.98 tbr, 600 tbn, 1200 tbc (default)
Metadata:
rotate : 90
creation_time : 2014-07-20 09:47:08
handler_name : Core Media Data Handler
encoder : H.264
Side data:
displaymatrix: rotation of -90.00 degrees
Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 63 kb/s (default)
Metadata:
creation_time : 2014-07-20 09:47:08
handler_name : Core Media Data Handler
[swscaler @ 0x7fe1e9800600] deprecated pixel format used, make sure you did set range correctly
Output #0, image2, to '/Users/lun/client/bookagoo/public/uploads/5405e9b0486f75a36c100000/video/1410641311nyv99k1j-IMG_0040_1_-edited.jpg':
Metadata:
major_brand : qt
minor_version : 0
compatible_brands: qt
make-rus : Apple
model : iPhone 4
model-rus : iPhone 4
make : Apple
encoder : Lavf55.48.100
date : 2014-07-20T13:47:08+0400
date-rus : 2014-07-20T13:47:08+0400
Stream #0:0(und): Video: mjpeg, yuvj420p, 480x360, q=2-31, 200 kb/s, 23.98 fps, 23.98 tbn, 23.98 tbc (default)
Metadata:
rotate : 90
creation_time : 2014-07-20 09:47:08
handler_name : Core Media Data Handler
encoder : Lavc55.69.100 mjpeg
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> mjpeg (native))
Press [q] to stop, [?] for help
frame= 0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)
这只发生在mov文件中。有几个棘手的地方，它似乎试图从视频中截取屏幕截图。
也许有人见过类似的东西，可以给我一个提示？
答案 0 :(得分：1)
您的命令告诉ffmpeg跳过前5秒，但控制台输出表明输入持续时间仅为00:00:01.84（不到2秒）。
如果您尝试从持续时间不同的各种输入中截取屏幕截图，则可以查看select filter而非使用-ss。
创建各种场景的马赛克示例：
ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
ffprobe与-ss 或者，通过某些脚本，您可以使用ffprobe to get the duration，然后为-ss计算适当的值。