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            linux中使用ffmpeg 无损剪切/拼接视频程序

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            • 来源:124软件资讯网

                剪切/拼接视频文件是一种常见需求  。在线视频网站现在往往将一个视频文件支解成 n 段  ,以淘汰流量消耗  。使用 DownloadHelper/DownThemAll 这类工具下载下来的往往就是支解后的文件 。能实现剪切/拼接视频文件的工具多种多样  ,但往往都需要举行视频重编码(transcoding) ,这就不行制止的带来了视频质量上的消耗  ,更不用提那长的怒不可遏的转换时间了…

                实在借助 ffmpeg 我们就可以在不举行视频重编码的情形下完成此类使命:

                剪切:

              代码如下
              ffmpeg -i input.mp4 -ss **START_TIME** -t **STOP_TIME** -acodec copy -vcodec copy output.mp4

                其中 START_TIME/STOP_TIME 的花样可以写成两种花样:

                以秒为单元计数: 80

                时:分:秒: 00:01:20

                拼接 :

                拼接的情形稍微庞大些  ,我们需要将需要拼接的视频文件按以下花样生存在一个列表 list.txt 中:

              代码如下
              file '/path/to/file1'
              file '/path/to/file2'
              file '/path/to/file3'

                响应的下令为:

              代码如下
              ffmpeg -f concat -i **list.txt** -c copy output.mp4

                由于不需要重编码  ,这两条下令险些是即时完成的  。

                利便起见 ,我写了一个剧本来简化操作  。放在 github 上 ,请自取:

              代码如下

              #!/bin/bash
              #cut/join videos using ffmpeg without quality loss

              if [ -z $1 ] || [ -z $2 ]; then
              echo "Usage:$0 c[ut] seconds <File>"
              echo " eg. $0 c 10 80 example.mp4"
              echo " eg. $0 c 00:00:10 00:01:20 example.mp4"
              echo "Usage:$0 j[oin] <FileType>"
              echo " eg. $0 j avi"
              exit
              fi

              case "$1" in
              c)
              echo "cuttig video..."
              fileName=$(echo $4 | cut -f 1 -d '.')
              fileType=$(echo $4 | cut -f 2 -d '.')
              ffmpeg -i $4 -ss $2 -t $3 -acodec copy -vcodec copy $fileName-$2-$3.$fileType
              ;;
              j)
              echo "joinning videos..."
              rm temp_list.txt
              for f in ./*.$2; do echo "file '$f'" >> temp_list.txt; done
              printf "file '%s'\n" ./*.$2 > temp_list.txt
              ffmpeg -f concat -i temp_list.txt -c copy output.$2
              rm temp_list.txt
              ;;
              *)
              echo "wrong arguments"
              ;;
              esac
              exit

                以上拼接操作生效的条件是  ,所有视频文件的花样编码相同  ,若是需要拼接差别花样的视频文件可以借助以下剧本

              代码如下

              # change this to what you need !!!
              EXTRA_OPTIONS='-vcodec libx264 -crf 23 -preset medium -acodec aac -strict experimental -ac 2 -ar 44100 -ab 128k'

              ################################################################################
              #
              # NO NEED TO TOUCH ANYTHING AFTER THIS LINE!
              #
              ################################################################################

              # the version of the script
              VERSION=1.3

              # location of temp folder
              TMP=/tmp

              ################################################################################

              echo "MultiMedia Concat Script v$VERSION (mmcat) - A script to concatenate multiple multimedia files."
              echo "Based on FFmpeg - www.ffmpeg.org"
              echo "Don't forget to edit this script and change EXTRA_OPTIONS"
              echo ""

              ################################################################################
              # syntax check (has to have at least 3 params: infile1, infile2, outfile
              ################################################################################
              if [ -z $3 ]; then
              echo "Syntax: $0 ... "
              exit 1
              fi

              ################################################################################
              # get all the command line parameters, except for the last one, which is output
              ################################################################################
              # $first - first parameter
              # $last - last parameter (output file)
              # $inputs - all the inputs, except the first input, because 1st input is
              # handled separately
              ################################################################################
              first=${@:1:1}
              last=${@:$#:1}
              len=$(($#-2))
              inputs=${@:2:$len}

              # remove all previous tmp fifos (if exist)
              rm -f $TMP/mcs_*

              ################################################################################
              # decode first input differently, because the video header does not have to be
              # kept for each video input, only the header from the first video is needed
              ################################################################################
              mkfifo $TMP/mcs_a1 $TMP/mcs_v1

              ffmpeg -y -i $first -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 $TMP/mcs_a1 2>/dev/null ffmpeg -y -i $first -an -f yuv4mpegpipe -vcodec rawvideo $TMP/mcs_v1 2>/dev/null
              # if you need to log the output of decoding processes (usually not necessary)
              # then replace the "2>/dev/null" in 2 lines above with your log file names, like this:
              #ffmpeg -y -i $first -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 $TMP/mcs_a1 2>$TMP/log.a.1 #ffmpeg -y -i $first -an -f yuv4mpegpipe -vcodec rawvideo $TMP/mcs_v1 2>$TMP/log.v.1
              ################################################################################
              # decode all the other inputs, remove first line of video (header) with tail
              # $all_a and $all_v are lists of all a/v fifos, to be used by "cat" later on
              ################################################################################
              all_a=$TMP/mcs_a1
              all_v=$TMP/mcs_v1
              i=2
              for f in $inputs
              do
              mkfifo $TMP/mcs_a$i $TMP/mcs_v$i

              ffmpeg -y -i $f -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 $TMP/mcs_a$i 2>/dev/null { ffmpeg -y -i $f -an -f yuv4mpegpipe -vcodec rawvideo - 2>/dev/null $TMP/mcs_v$i ; } &

              # if you need to log the output of decoding processes (usually not necessary)
              # then replace the "2>/dev/null" in 2 lines above with your log file names, like this:
              #ffmpeg -y -i $f -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 $TMP/mcs_a$i 2>$TMP/log.a.$i #{ ffmpeg -y -i $f -an -f yuv4mpegpipe -vcodec rawvideo - 2>$TMP/log.v.$i $TMP/mcs_v$i ; } &

              all_a="$all_a $TMP/mcs_a$i"
              all_v="$all_v $TMP/mcs_v$i"
              let i++
              done

              ################################################################################
              # concatenate all raw audio/video inputs into one audio/video
              ################################################################################
              mkfifo $TMP/mcs_a_all
              mkfifo $TMP/mcs_v_all
              cat $all_a > $TMP/mcs_a_all &
              cat $all_v > $TMP/mcs_v_all &

              ################################################################################
              # finally, encode the raw concatenated audio/video into something useful
              ################################################################################
              ffmpeg -f u16le -acodec pcm_s16le -ac 2 -ar 44100 -i $TMP/mcs_a_all \
              -f yuv4mpegpipe -vcodec rawvideo -i $TMP/mcs_v_all \
              $EXTRA_OPTIONS \
              $last

              ################################################################################
              # remove all fifos
              ################################################################################
              rm -f $TMP/mcs_*