使用案例
当用户录制音频文件并上传到firebase存储时，运行触发器以裁剪该文件的剪辑并将其保存到“预览”目录。
问题
当文件到达服务器时，它在开始时间（10秒）之前就是死空气，然后在超过10秒的持续时间后不再停止。无论我在“-t”和“-ss”参数中放置什么似乎对输出文件没有影响 - 没有正确裁剪。
环境
节点代码
var command = new ffmpeg({ source: tempFilePath, timeout: 0 })
.setFfmpegPath(ffmpegPath)
.setFfprobePath(ffprobePath)
.inputOption('-t', '10')
.inputOption('-ss', '10')
.outputOption('-acodec', 'copy')
.on('start', function(commandLine) {
console.log('Spawned Ffmpeg with command: ', commandLine);
})
.on('end', function() {
console.log('Preview file cropping done successfully');
})
.on('error', function(err, stdout, stderr) {
var build = err;
if (!stdout === '') { build = build + '\n' + stdout; }
build = build + '\n' + stderr;
console.log(build);
}).save(tempFilePath);
Ffmpeg Command
使用命令生成Ffmpeg：ffmpeg -t 10 -i /tmp/2EB100B0-6C1E-4D51-9087-764CA653AFC720170711232034.aac -y -acodec aac /tmp/2EB100B0-6C1E-4D51-9087-764CA653AFC720170711232034.aac
控制台输出
$ ffmpeg -t 10 -i E506FE2E-DC81-4DD8-B751-211F7FD9A25820170816160502.aac -y -acodec aac output.aac -loglevel debug
ffmpeg version 3.2.2 Copyright (c) 2000-2016 the FFmpeg developers
built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc --arch=x86_64 --enable-runtime-cpudetect
libavutil 55. 34.100 / 55. 34.100
libavcodec 57. 64.101 / 57. 64.101
libavformat 57. 56.100 / 57. 56.100
libavdevice 57. 1.100 / 57. 1.100
libavfilter 6. 65.100 / 6. 65.100
libswscale 4. 2.100 / 4. 2.100
libswresample 2. 3.100 / 2. 3.100
libpostproc 54. 1.100 / 54. 1.100
Splitting the commandline.
Reading option '-t' ... matched as option 't' (record or transcode "duration" seconds of audio/video) with argument '10'.
Reading option '-i' ... matched as input url with argument 'E506FE2E-DC81-4DD8-B751-211F7FD9A25820170816160502.aac'.
Reading option '-y' ... matched as option 'y' (overwrite output files) with argument '1'.
Reading option '-acodec' ... matched as option 'acodec' (force audio codec ('copy' to copy stream)) with argument 'aac'.
Reading option 'output.aac' ... matched as output url.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument 'debug'.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option y (overwrite output files) with argument 1.
Applying option loglevel (set logging level) with argument debug.
Successfully parsed a group of options.
Parsing a group of options: input url E506FE2E-DC81-4DD8-B751-211F7FD9A25820170816160502.aac.
Applying option t (record or transcode "duration" seconds of audio/video) with argument 10.
Successfully parsed a group of options.
Opening an input file: E506FE2E-DC81-4DD8-B751-211F7FD9A25820170816160502.aac.
[file @ 0x7fe42f700420] Setting default whitelist 'file,crypto'
[aac @ 0x7fe431000000] Format aac probed with size=2048 and score=51
[aac @ 0x7fe431000000] Before avformat_find_stream_info() pos: 0 bytes read:32928 seeks:4 nb_streams:1
[aac @ 0x7fe431000000] All info found
[aac @ 0x7fe431000000] Estimating duration from bitrate, this may be inaccurate
[aac @ 0x7fe431000000] After avformat_find_stream_info() pos: 37888 bytes read:98464 seeks:4 frames:50
Input #0, aac, from 'E506FE2E-DC81-4DD8-B751-211F7FD9A25820170816160502.aac':
Duration: 00:01:24.28, bitrate: 335 kb/s
Stream #0:0, 50, 1/28224000: Audio: aac (LC), 44100 Hz, stereo, fltp, 335 kb/s
Successfully opened the file.
Parsing a group of options: output url output.aac.
Applying option acodec (force audio codec ('copy' to copy stream)) with argument aac.
Successfully parsed a group of options.
Opening an output file: output.aac.
[file @ 0x7fe42f7016e0] Setting default whitelist 'file,crypto'
Successfully opened the file.
detected 4 logical cores
[graph 0 input from stream 0:0 @ 0x7fe42f701880] Setting 'time_base' to value '1/44100'
[graph 0 input from stream 0:0 @ 0x7fe42f701880] Setting 'sample_rate' to value '44100'
[graph 0 input from stream 0:0 @ 0x7fe42f701880] Setting 'sample_fmt' to value 'fltp'
[graph 0 input from stream 0:0 @ 0x7fe42f701880] Setting 'channel_layout' to value '0x3'
[graph 0 input from stream 0:0 @ 0x7fe42f701880] tb:1/44100 samplefmt:fltp samplerate:44100 chlayout:0x3
[audio format for output stream 0:0 @ 0x7fe42f702060] Setting 'sample_fmts' to value 'fltp'
[audio format for output stream 0:0 @ 0x7fe42f702060] Setting 'sample_rates' to value '96000|88200|64000|48000|44100|32000|24000|22050|16000|12000|11025|8000|7350'
[AVFilterGraph @ 0x7fe42f6101a0] query_formats: 5 queried, 12 merged, 0 already done, 0 delayed
Output #0, adts, to 'output.aac':
Metadata:
encoder : Lavf57.56.100
Stream #0:0, 0, 1/44100: Audio: aac (LC), 44100 Hz, stereo, fltp, delay 1024, 128 kb/s
Metadata:
encoder : Lavc57.64.101 aac
Stream mapping:
Stream #0:0 -> #0:0 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
cur_dts is invalid (this is harmless if it occurs once at the start per stream)
Last message repeated 1 times
[output stream 0:0 @ 0x7fe42f701ee0] EOF on sink link output stream 0:0:default.
No more output streams to write to, finishing.
[aac @ 0x7fe431001200] Trying to remove 344 more samples than there are in the queue
size= 160kB time=00:00:10.00 bitrate= 130.9kbits/s speed=20.2x
video:0kB audio:157kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.881580%
Input file #0 (E506FE2E-DC81-4DD8-B751-211F7FD9A25820170816160502.aac):
Input stream #0:0 (audio): 432 packets read (398208 bytes); 432 frames decoded (442368 samples);
Total: 432 packets (398208 bytes) demuxed
Output file #0 (output.aac):
Output stream #0:0 (audio): 431 frames encoded (441000 samples); 432 packets muxed (160716 bytes);
Total: 432 packets (160716 bytes) muxed
432 frames successfully decoded, 0 decoding errors
[AVIOContext @ 0x7fe42f611040] Statistics: 0 seeks, 432 writeouts
[aac @ 0x7fe431001200] Qavg: 4508.253
[AVIOContext @ 0x7fe42f7004c0] Statistics: 458912 bytes read, 4 seeks