How to get the offset of a video stream of a mp4 container with ffmpeg?

Question

I can encode a video stream inside a mp4 container with a 1 second offset by running this command:

ffmpeg -i input.mp3 -itsoffset 1 -t 3 -i input.mp4 -c:v copy output.mp4

How can I get back a stream's offset with ffmpeg?

Using this command, I can get information on a specific stream (e.g. the video stream in this case):

ffmpeg -i input.mp4 -c copy -map 0:v -f null -

I get useful information, such as the duration of the stream, however the offset is never included.

Note that I can't use ffprobe.

EDIT

Full log for this command: ffmpeg -i input.mp4 -map 0:v -frames 1 -f null -

I know this version is old, but I don't have control on the version.

ffmpeg version n3.1.2 Copyright (c) 2000-2016 the FFmpeg developers
built with emcc (Emscripten gcc/clang-like replacement) 1.36.7 ()
configuration: --cc=emcc --enable-cross-compile --target-os=none --arch=x86 --disable-runtime-cpudetect --disable-asm --disable-fast-unaligned --disable-pthreads --disable-w32threads --disable-os2threads --disable-debug --disable-stripping --disable-all --enable-ffmpeg --enable-avcodec --enable-avformat --enable-avutil --enable-swresample --enable-swscale --enable-avfilter --disable-network --disable-d3d11va --disable-dxva2 --disable-vaapi --disable-vda --disable-vdpau --enable-decoder=vp8 --enable-decoder=vp9 --enable-decoder=theora --enable-decoder=mpeg2video --enable-decoder=mpeg4 --enable-decoder=h264 --enable-decoder=hevc --enable-decoder=png --enable-decoder=mjpeg --enable-decoder=vorbis --enable-decoder=opus --enable-decoder=mp3 --enable-decoder=ac3 --enable-decoder=aac --enable-decoder=ass --enable-decoder=ssa --enable-decoder=srt --enable-decoder=webvtt --enable-demuxer=matroska --enable-demuxer=ogg --enable-demuxer=avi --enable-demuxer=mov --enable-demuxer=flv --enable-demuxer=mpegps --enable-demuxer=image2 --enable-demuxer=mp3 --enable-demuxer=concat --enable-protocol=file --enable-filter=aresample --enable-filter=scale --enable-filter=crop --enable-filter=overlay --disable-bzlib --disable-iconv --disable-libxcb --disable-lzma --disable-sdl --disable-securetransport --disable-xlib --disable-zlib --enable-encoder=libx264 --enable-encoder=libmp3lame --enable-encoder=aac --enable-muxer=mp4 --enable-muxer=mp3 --enable-muxer=null --enable-gpl --enable-libmp3lame --enable-libx264 --extra-cflags=-I../lame/dist/include --extra-ldflags=-L../lame/dist/lib
libavutil      55. 28.100 / 55. 28.100
libavcodec     57. 48.101 / 57. 48.101
libavformat    57. 41.100 / 57. 41.100
libavfilter     6. 47.100 /  6. 47.100
libswscale      4.  1.100 /  4.  1.100
libswresample   2.  1.100 /  2.  1.100
[h264 @ 0x809db0] Warning: not compiled with thread support, using thread emulation
[aac @ 0x80edf0] Warning: not compiled with thread support, using thread emulation
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4':
Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.41.100
Duration: 00:00:07.08, start: 0.000000, bitrate: 137 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 100x100 [SAR 1:1 DAR 1:1], 4 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
    handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 129 kb/s (default)
    Metadata:
    handler_name    : SoundHandler
Output #0, null, to 'pipe:':
Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.41.100
    Stream #0:0(und): Unknown: none (default)
    Metadata:
    handler_name    : VideoHandler
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> ? (?))
Encoder (codec wrapped_avframe) not found for output stream #0:0

Do you mean the offset in bytes? – szatmary Mar 09 '19 at 18:00 — szatmary, Mar 09 '19 at 18:00
Nope the offset in seconds – Maxime Dupré Mar 11 '19 at 16:23 — Maxime Dupré, Mar 11 '19 at 16:23

score -1 · Accepted Answer · answered Mar 09 '19 at 08:35

-1

Without producing a verbose log, you can come close by running

ffmpeg -copyts -i input.mp4 -r 1000 -map 0:v -frames 1 -f null -

The time value in the output should be the PTS of the first frame.

answered Mar 09 '19 at 08:35

Gyan

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It does not seem to work. With an offset of 3 on the video stream. I get: `frame= 1 fps=0.0 q=-1.0 Lsize=N/A time=-00:00:00.07 bitrate=N/A speed=N/A `. Also I had to add `-c copy` to the command, or I got this error: "Encoder (codec wrapped_avframe) not found for output stream #0:0". – Maxime Dupré Mar 11 '19 at 16:25
Share full log. You can't use -c copy for this. – Gyan Mar 11 '19 at 16:50
Thanks to your answer, I was able to make it work with this command: `-i input.mp4 -c copy -map 0:v -frames 1 -f null -`. I also had to `-copyts` in the command that creates `input.mp4`. Please update answer to include those details so that I can accept the answer :). – Maxime Dupré Mar 11 '19 at 16:50
`-c copy` will give wrong answer for codecs with delay. It will give first DTS, not PTS. – Gyan Mar 11 '19 at 16:54
Not optimal, but try `ffmpeg -copyts -i input.mp4 -r 1000 -map 0:v -c:v libx264 -frames 1 -f null -` – Gyan Mar 11 '19 at 18:16
It seems like adding `-copyts` when decoding/analyzing the output like you did in your answer has no effect. `-copyts` needs to be added in the encoding command. Is this a normal behaviour? – Maxime Dupré Mar 12 '19 at 16:29
I include it for safety. null muxer is variable FPS, so it can be dipensed of, here. – Gyan Mar 12 '19 at 16:55

How to get the offset of a video stream of a mp4 container with ffmpeg?

1 Answers1