Duration with -t before -i is actually value of -t plus value of -ss using -codec copy

[Piscium]

If I run the command below I would expect the duration of the output file to be 30 seconds, but instead it is 40.

ffmpeg -y -ss 10 -t 30 -i in.m4a -acodec copy -flags global_header out.m4a

It seems this is a bug. It may be the same bug or related to bug #4475.

In case somebody else comes across this bug, the workaround is to subtract the value of the -ss parameter from the value of the -t parameter, as follows:

ffmpeg -y -ss 10 -t 20 -i in.m4a -acodec copy -flags global_header out.m4a

With the above I get the intended duration of 30 seconds.

Note that if the duration is less than the seek point you need to enter a negative duration for the workaround, for example the command below will also give me the desired duration of 30 seconds.

ffmpeg -y -ss 92 -t -62 -i in.m4a -acodec copy -flags global_header out.m4a

---

ffmpeg -version
ffmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by ffmpeg)
ffmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by /lib64/libavfilter.so.5)
ffmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by /lib64/libavutil.so.54)
ffmpeg version 2.4.10 Copyright (c) 2000-2015 the FFmpeg developers
built on Jun 3 2015 08:36:36 with gcc 4.9.2 (GCC) 20150212 (Red Hat 4.9.2-6)
configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
libavutil 54. 7.100 / 54. 7.100
libavcodec 56. 1.100 / 56. 1.100
libavformat 56. 4.101 / 56. 4.101
libavdevice 56. 0.100 / 56. 0.100
libavfilter 5. 1.100 / 5. 1.100
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 0.100 / 3. 0.100
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 0.100 / 53. 0.100

[Piscium]

The bug seems to be in the copy codec, it does not manifest in the command below that does not use it:

ffmpeg -y -ss 10 -t 30 -i in.m4a -flags global_header -af afade=t=in:st=0:d=5,afade=t=out:st=25:d=5 out.mp3

[Carl Eugen Hoyos]

Please test current FFmpeg git head and provide the command line that allows to reproduce the issue together with the complete, uncut console output to make this a valid ticket.

[Piscium]

Below is the full console output for ffmpeg version 2.4.10 currently installed on my PC. This command line has my workaround whereby I ask for a duration of 20 seconds to get what I want which is 30 seconds.

I will see if I find time to test the git head - no promises.

---

$ ffmpeg -y -ss 10 -t 20 -i in.m4a -acodec copy -flags global_header out.m4affmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by ffmpeg)
ffmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by /lib64/libavfilter.so.5)
ffmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by /lib64/libavutil.so.54)
ffmpeg version 2.4.10 Copyright (c) 2000-2015 the FFmpeg developers

built on Jun 3 2015 08:36:36 with gcc 4.9.2 (GCC) 20150212 (Red Hat 4.9.2-6)
configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
libavutil 54. 7.100 / 54. 7.100
libavcodec 56. 1.100 / 56. 1.100
libavformat 56. 4.101 / 56. 4.101
libavdevice 56. 0.100 / 56. 0.100
libavfilter 5. 1.100 / 5. 1.100
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 0.100 / 3. 0.100
libswresample 1. 1.100 / 1. 1.100
libpostproc 53. 0.100 / 53. 0.100

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.m4a':

Metadata:

major_brand : dash
minor_version : 0
compatible_brands: iso6mp41
creation_time : 2014-01-25 16:58:44

Duration: 00:02:40.08, start: 0.000000, bitrate: 255 kb/s

Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 253 kb/s (default)
Metadata:

creation_time : 2014-01-25 16:58:44
handler_name : SoundHandler

Output #0, ipod, to 'out.m4a':

Metadata:

major_brand : dash
minor_version : 0
compatible_brands: iso6mp41
encoder : Lavf56.4.101
Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, 253 kb/s (default)
Metadata:

creation_time : 2014-01-25 16:58:44
handler_name : SoundHandler

Stream mapping:

Stream #0:0 -> #0:0 (copy)

Press [q] to stop, ? for help
size= 935kB time=00:00:30.00 bitrate= 255.3kbits/s
video:0kB audio:929kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.620911%

[Piscium]

OK, I managed to build the git head of ffmpeg. It was easy. I used build configuration options as close as I possible to the version where I found the bug.

How do I run the git version that I built without installing it. Is there a way?

Anyway, I just called ffmpeg from the directory where I built the git head and got the same results, i. e., the bug is still there. However I am not sure I picked up the freshly built libraries, I may have picked up the old libraries that are installed in /usr/lib64.

---

$ ./ffmpeg -y -ss 10 -t 20 -i in.m4a -acodec copy -flags global_header out.m4a
./ffmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by ./ffmpeg)
./ffmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by /lib64/libavfilter.so.5)
./ffmpeg: /usr/lib64/nvidia-304xx/libOpenCL.so.1: no version information available (required by /lib64/libavutil.so.54)
ffmpeg version N-73411-g5233f25 Copyright (c) 2000-2015 the FFmpeg developers

built with gcc 4.9.2 (GCC) 20150212 (Red Hat 4.9.2-6)
configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
WARNING: library configuration mismatch
avutil configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
avcodec configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
avformat configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
avdevice configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
avfilter configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
avresample configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
swscale configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
swresample configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
postproc configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --enable-bzlib --disable-crystalhd --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libcdio --enable-libdc1394 --disable-indev=jack --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-openal --enable-opencl --enable-libopencv --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-x11grab --enable-avfilter --enable-avresample --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-runtime-cpudetect
libavutil 54. 28.100 / 54. 7.100
libavcodec 56. 46.101 / 56. 1.100
libavformat 56. 40.100 / 56. 4.101
libavdevice 56. 4.100 / 56. 0.100
libavfilter 5. 20.100 / 5. 1.100
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 0.100
libswresample 1. 2.100 / 1. 1.100
libpostproc 53. 3.100 / 53. 0.100

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.m4a':

Metadata:

major_brand : dash
minor_version : 0
compatible_brands: iso6mp41
creation_time : 2014-01-25 16:58:44

Duration: 00:02:40.08, start: 0.000000, bitrate: 255 kb/s

Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 253 kb/s (default)
Metadata:

creation_time : 2014-01-25 16:58:44
handler_name : SoundHandler

Output #0, ipod, to 'out.m4a':

Metadata:

major_brand : dash
minor_version : 0
compatible_brands: iso6mp41
encoder : Lavf56.4.101
Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, 253 kb/s (default)
Metadata:

creation_time : 2014-01-25 16:58:44
handler_name : SoundHandler

Stream mapping:

Stream #0:0 -> #0:0 (copy)

Press [q] to stop, ? for help
size= 935kB time=00:00:30.00 bitrate= 255.3kbits/s
video:0kB audio:929kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.620911%

[Piscium]

I rebuilt ffmpeg with the default ./configure options and the bug is still there.

It seems that the ffmpeg libraries are built statically in ffmpeg, so my concern about picking up old libraries was likely incorrect.

---

$ ldd ./ffmpeg

linux-vdso.so.1 => (0x00007ffff516a000)
libXv.so.1 => /lib64/libXv.so.1 (0x00007f2cb1bfd000)
libX11.so.6 => /lib64/libX11.so.6 (0x00007f2cb18ba000)
libXext.so.6 => /lib64/libXext.so.6 (0x00007f2cb16a8000)
libva.so.1 => /lib64/libva.so.1 (0x00007f2cb1492000)
libxcb.so.1 => /lib64/libxcb.so.1 (0x00007f2cb1270000)
libxcb-shm.so.0 => /lib64/libxcb-shm.so.0 (0x00007f2cb106c000)
libxcb-xfixes.so.0 => /lib64/libxcb-xfixes.so.0 (0x00007f2cb0e64000)
libxcb-shape.so.0 => /lib64/libxcb-shape.so.0 (0x00007f2cb0c60000)
libjack.so.0 => /lib64/libjack.so.0 (0x00007f2cb0a05000)
libasound.so.2 => /lib64/libasound.so.2 (0x00007f2cb071c000)
libSDL-1.2.so.0 => /lib64/libSDL-1.2.so.0 (0x00007f2cb047f000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f2cb0263000)
libm.so.6 => /lib64/libm.so.6 (0x00007f2caff5b000)
liblzma.so.5 => /lib64/liblzma.so.5 (0x00007f2cafd36000)
libbz2.so.1 => /lib64/libbz2.so.1 (0x00007f2cafb26000)
libz.so.1 => /lib64/libz.so.1 (0x00007f2caf910000)
libvdpau.so.1 => /lib64/libvdpau.so.1 (0x00007f2caf70c000)
libc.so.6 => /lib64/libc.so.6 (0x00007f2caf34f000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f2caf14b000)
libXau.so.6 => /lib64/libXau.so.6 (0x00007f2caef47000)
libopus.so.0 => /lib64/libopus.so.0 (0x00007f2caecfb000)
librt.so.1 => /lib64/librt.so.1 (0x00007f2caeaf3000)
libstdc++.so.6 => /lib64/libstdc++.so.6 (0x00007f2cae7e4000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f2cae5cd000)
/lib64/ld-linux-x86-64.so.2 (0x00007f2cb1e02000)

[Piscium]

Built with default options.

---

$ ./ffmpeg -y -ss 10 -t 20 -i in.m4a -acodec copy -flags global_header out.m4a
ffmpeg version N-73411-g5233f25 Copyright (c) 2000-2015 the FFmpeg developers

built with gcc 4.9.2 (GCC) 20150212 (Red Hat 4.9.2-6)
configuration:
libavutil 54. 28.100 / 54. 28.100
libavcodec 56. 46.101 / 56. 46.101
libavformat 56. 40.100 / 56. 40.100
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 20.100 / 5. 20.100
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 2.100 / 1. 2.100

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'in.m4a':

Metadata:

major_brand : dash
minor_version : 0
compatible_brands: iso6mp41
creation_time : 2014-01-25 16:58:44

Duration: 00:02:40.08, start: 0.000000, bitrate: 255 kb/s

Stream #0:0(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 253 kb/s (default)
Metadata:

creation_time : 2014-01-25 16:58:44
handler_name : SoundHandler

Output #0, ipod, to 'out.m4a':

Metadata:

major_brand : dash
minor_version : 0
compatible_brands: iso6mp41
encoder : Lavf56.40.100
Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, 253 kb/s (default)
Metadata:

creation_time : 2014-01-25 16:58:44
handler_name : SoundHandler

Stream mapping:

Stream #0:0 -> #0:0 (copy)

Press [q] to stop, ? for help
size= 935kB time=00:00:30.00 bitrate= 255.3kbits/s
video:0kB audio:929kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.621016%

[Carl Eugen Hoyos]

Duplicate of ticket #4475.