Question

I have multiple mpeg2 video files. What I need to do is get a clip of video that is contained in several of these mpeg2 videos. What I’m doing at the moment is:

• Join them using the command:

      copy /b file1.mpg + ... + fileN.mpg output.mpg
  

• The ouput.mpg duration is wrong so I’m using FFMpeg to fix that:

      ffmpeg -y -i output.mpeg -target pal-dvd outputFixed.mpg
  

The problem is when I try to extract only one portion of this output.mpg, at the same time I “fix” it, with the -ss and -t FFMpeg commands becouse the video duration is wrong as i said.

So the question is:

• Is there any way to combine Mpeg2 files without getting the duration wrong?
• Is there any way to fix the duration of a Mpeg2 file and extract one portion at the same time?

Any suggestion would be appreciated.

Answer 1

From the ffmpeg FAQ:

3.13 How can I join video files?

A few multimedia containers (MPEG-1, MPEG-2 PS, DV) allow to join
video files by merely concatenating them.

Hence you may concatenate your multimedia files by first transcoding
them to these privileged formats, then using the humble cat command
(or the equally humble copy under Windows), and finally transcoding
back to your format of choice.

ffmpeg -i input1.avi -same_quant intermediate1.mpg ffmpeg -i
input2.avi -same_quant intermediate2.mpg cat intermediate1.mpg
intermediate2.mpg > intermediate_all.mpg ffmpeg -i
intermediate_all.mpg -same_quant output.avi Notice that you should
either use -same_quant or set a reasonably high bitrate for your
intermediate and output files, if you want to preserve video quality.

Also notice that you may avoid the huge intermediate files by taking
advantage of named pipes, should your platform support it:

mkfifo intermediate1.mpg mkfifo intermediate2.mpg ffmpeg -i
input1.avi -same_quant -y intermediate1.mpg < /dev/null & ffmpeg -i
input2.avi -same_quant -y intermediate2.mpg < /dev/null & cat
intermediate1.mpg intermediate2.mpg |\ ffmpeg -f mpeg -i – -same_quant
-c:v mpeg4 -acodec libmp3lame output.avi Similarly, the yuv4mpegpipe format, and the raw video, raw audio codecs also allow concatenation,
and the transcoding step is almost lossless. When using multiple
yuv4mpegpipe(s), the first line needs to be discarded from all but the
first stream. This can be accomplished by piping through tail as seen
below. Note that when piping through tail you must use command
grouping, { ;}, to background properly.

For example, let’s say we want to join two FLV files into an
output.flv file:

mkfifo temp1.a mkfifo temp1.v mkfifo temp2.a mkfifo temp2.v mkfifo
all.a mkfifo all.v ffmpeg -i input1.flv -vn -f u16le -acodec pcm_s16le
-ac 2 -ar 44100 – > temp1.a < /dev/null & ffmpeg -i input2.flv -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 – > temp2.a < /dev/null &
ffmpeg -i input1.flv -an -f yuv4mpegpipe – > temp1.v < /dev/null & {
ffmpeg -i input2.flv -an -f yuv4mpegpipe – < /dev/null | tail -n +2 >
temp2.v ; } & cat temp1.a temp2.a > all.a & cat temp1.v temp2.v >
all.v & ffmpeg -f u16le -acodec pcm_s16le -ac 2 -ar 44100 -i all.a \
-f yuv4mpegpipe -i all.v \
-same_quant -y output.flv rm temp[12].[av] all.[av]