I have a problem with video mp4 concatenation using ffmpeg. I have two the same videos and I want to concatenate them. I created file inputs.txt and then used command:
ffmpeg -f concat -i inputs.txt -c copy mergedVideo.mp4
Output:
ffmpeg -f concat -i inputs.txt -c copy mergedVideo.mp4
ffmpeg version 5.0.1 Copyright (c) 2000-2022 the FFmpeg developers
built with clang version 12.0.1
configuration: --prefix=/Users/runner/miniforge3/conda-bld/ffmpeg_1649114094397/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_pl --cc=arm64-apple-darwin20.0.0-clang --disable-doc --disable-openssl --enable-demuxer=dash --enable-gnutls --enable-gpl --enable-hardcoded-tables --enable-libfreetype --enable-libopenh264 --enable-neon --enable-libx264 --enable-libx265 --enable-libaom --enable-libsvtav1 --enable-libxml2 --enable-libvpx --enable-pic --enable-pthreads --enable-shared --disable-static --enable-version3 --enable-zlib --enable-libmp3lame --pkg-config=/Users/runner/miniforge3/conda-bld/ffmpeg_1649114094397/_build_env/bin/pkg-config --enable-cross-compile --arch=arm64 --target-os=darwin --cross-prefix=arm64-apple-darwin20.0.0- --host-cc=/Users/runner/miniforge3/conda-bld/ffmpeg_1649114094397/_build_env/bin/x86_64-apple-darwin13.4.0-clang
libavutil 57. 17.100 / 57. 17.100
libavcodec 59. 18.100 / 59. 18.100
libavformat 59. 16.100 / 59. 16.100
libavdevice 59. 4.100 / 59. 4.100
libavfilter 8. 24.100 / 8. 24.100
libswscale 6. 4.100 / 6. 4.100
libswresample 4. 3.100 / 4. 3.100
libpostproc 56. 3.100 / 56. 3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x1561044a0] Auto-inserting h264_mp4toannexb bitstream filter
Input #0, concat, from 'inputs.txt':
Duration: N/A, start: -0.064000, bitrate: 1424 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 1355 kb/s, 50 fps, 50 tbr, 12800 tbn
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 16000 Hz, mono, fltp, 68 kb/s
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
File 'mergedVideo.mp4' already exists. Overwrite? [y/N] y
Output #0, mp4, to 'mergedVideo.mp4':
Metadata:
encoder : Lavf59.16.100
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 1355 kb/s, 50 fps, 50 tbr, 12800 tbn
Metadata:
handler_name : VideoHandler
vendor_id : [0][0][0][0]
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 16000 Hz, mono, fltp, 68 kb/s
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame= 0 fps=0.0 q=-1.0 size= 0kB time=00:00:00.06 bitrate= 6.0k[mov,mp4,m4a,3gp,3g2,mj2 @ 0x154f28b20] Auto-inserting h264_mp4toannexb bitstream filter
frame= 166 fps=0.0 q=-1.0 Lsize= 583kB time=00:00:03.39 bitrate=1407.4kbits/s speed= 179x
video:550kB audio:29kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.737394%
Unfortunately the result is different then I expected:
movies comparison
The output is longer than the length of two inputs. Any thoughts?
Also I tried using different commands:
ffmpeg -f concat -i inputs.txt -c copy mergedVideo.mp4
or set the framerate:
ffmpeg -r 50 -f concat -i inputs.txt -c copy mergedVideo.mp4
What is also weird that I have the same problem when using moviepy library.
from moviepy.editor import VideoFileClip, concatenate_videoclips
videos = [VideoFileClip("0.mp4"), VideoFileClip("0.mp4")]
concatenate_videoclips(videos).write_videofile('mergedVideo.mp4')
Update ffprobe command for output file
ffprobe -v error -select_streams v -show_entries stream=codec_name,time_base,start_pts,start_time,duration -of default=noprint_wrappers=1 mergedVideo.mp4
codec_name=h264
time_base=1/12800
start_pts=0
start_time=0.000000
duration=3.380000
For input:
ffprobe -v error -select_streams v -show_entries stream=codec_name,time_base,start_pts,start_time,duration -of default=noprint_wrappers=1 0.mp4
codec_name=h264
time_base=1/12800
start_pts=0
start_time=0.000000
duration=1.660000
The duration supposed to be 2*1.66 = 3.32 and but it's 3.38.
Content of the inputs.txt
file '0.mp4'
file '0.mp4'