怎么判断是不是错了？

Question

的情况：

我使用ffmpeg (通过php)转换视频文件。我将转换脚本配置为从exec()命令返回输出(作为$error数组)。我的假设是，如果没有发生错误，$error将是一个空数组。

问题：

问题是，即使在转换中没有错误，脚本也会返回输出。(我可以看出没有错误，因为输出了一个可播放的视频文件。)

问题：

ffmpeg如何格式化其错误/输出？我希望能够解析这一点，并确定是否发生了错误以及它是什么错误。

谢谢!

代码：

*一个无错误输出的例子：

FFmpeg version git-N-29201-g37c0a44, Copyright (c) 2000-2011 the FFmpeg developers|  built on Sep  9 2011 23:29:21 with gcc 4.1.2 20080704 (Red Hat 4.1.2-50)|  configuration: --prefix=/usr/local/hgffmpeg --enable-shared --enable-nonfree --enable-avfilter --enable-filter=movie --enable-gpl --enable-pthreads --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfaac --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --extra-cflags=-I/usr/local/hgffmpeg/include/ --extra-ldflags=-L/usr/local/hgffmpeg/lib --enable-decoder=ac3 --enable-decoder=asv1 --enable-decoder=asv2 --enable-decoder=flac --enable-decoder=wmv1 --enable-decoder=wmv2 --enable-decoder=wmv3 --enable-decoder=mpeg1video --enable-decoder=mpeg2video --enable-decoder=flv --enable-decoder=fraps --enable-decoder=h263 --enable-decoder=h264 --enable-decoder=libgsm --enable-decoder=mjpeg --enable-decoder=mpeg4 --enable-decoder=mpeg4aac --enable-decoder=mpegvideo --enable-decoder=mpeg4aac --enable-decoder=msmpeg4v1 --enable-decoder=msmpeg4v2 --enable-decoder=msmpeg4v3 --enable-decoder=pcm_alaw --enable-decoder=pcm_mulaw --enable-encoder=ac3 --enable-encoder=asv1 --enable-encoder=asv2 --enable-encoder=flac --enable-encoder=h263 --enable-encoder=flashsv --enable-encoder=flv --enable-encoder=libgsm --enable-encoder=mjpeg --enable-encoder=msmpeg4v3 --enable-encoder=pcm_alaw --enable-encoder=pcm_mulaw --enable-encoder=mpeg1video --enable-encoder=mpeg2video --enable-encoder=mpeg4 --enable-encoder=msmpeg4v1 --enable-encoder=msmpeg4v2 --enable-encoder=rv10 --enable-encoder=rv20 --enable-encoder=vorbis --enable-encoder=wmav1 --enable-encoder=wmav2 --enable-encoder=wmv1 --enable-encoder=wmv2 --disable-demuxer=v4l --disable-demuxer=v4l2 --enable-version3|  libavutil    50. 40. 1 / 50. 40. 1|  libavcodec   52.120. 0 / 52.120. 0|  libavformat  52.108. 0 / 52.108. 0|  libavdevice  52.  4. 0 / 52.  4. 0|  libavfilter   1. 79. 1 /  1. 79. 1|  libswscale    0. 13. 0 /  0. 13. 0|[mpeg1video @ 0x1f6d030] skipped MB in I frame at 5 0|[mpeg1video @ 0x1f6d030] Warning MVs not available|[mpeg1video @ 0x1f6d030] concealing 260 DC, 260 AC, 260 MV errors|[mpegvideo @ 0x1f6a660] Estimating duration from bitrate, this may be inaccurate|Input #0, mpegvideo, from '../uploads/test_vid/unencodedVideo.mpg':|  Duration: 00:00:00.01, bitrate: 104860 kb/s|    Stream #0.0: Video: mpeg1video, yuv420p, 320x200 [PAR 1:1 DAR 8:5], 104857 kb/s, 23.98 fps, 23.98 tbr, 1200k tbn, 23.98 tbc|WARNING: The bitrate parameter is set too low. It takes bits/s as argument, not kbits/s|File '../uploads/test_vid/video.flv' already exists. Overwrite ? [y/N] Not overwriting - exiting

Answer 1

假设您使用exec()来调用ffmpeg，您可能需要：

$lastline = exec('ffmpeg ...', $full_output, $return_var);

if ($return_var !== whatever_ffmpeg_returns_on_success) {
   die("ffmpeg failed");
}