[FFmpeg-user] ffmpeg generates videos with start time greater than 0
Alfredo Aiello
stuzzo at gmail.com
Wed Mar 11 19:49:30 CET 2015
I'm trying to cut videos with ffmpeg. I know how to do it in the "normal
way":
ffmpeg -i test.mp4 -ss 0 -t 6 -c:v libx264 -profile:v main -level
3.1 -preset medium -crf 20 -r 25 -b:v 1200k -minrate 1200k -maxrate
1200k -bufsize 1835k -c:a libfdk_aac -ar 48000 -ac 2 -ab 128k trimmed.mp4
Here's my problem. When I cut, but I noticed in others commands too,
when I check my file with
ffmpeg -i trimmed.mp4
output shows me this strange line:
Duration: 00:00:06.04, start: 0.042667
Why my video duration is 00:00:06.04? And why it starts on 0.042667?
In my application, I need that every video is exactly 6 seconds because
after I concat 6 videos, I put on them an overlay that shows a different
text every 6 seconds.
Actually the result video is not correct because the overlay isn't
synced with videos.
I tried my case with 6 videos that has Duration 00:00:06.00 and start
0.0000 and the result was ok.
Is there a way to set exactly the Duration and the start?
I found a similar problem here <https://trac.ffmpeg.org/ticket/3353>.
Command output:
ffmpeg -i sample.mov -ss 1 -t 6 -c:v libx264 -profile:v main -level
3.1 -preset medium -crf 20 -r 25 -b:v 1200k -minrate 1200k -maxrate
1200k -bufsize 1835k -c:a libfdk_aac -ar 48000 -ac 2 -ab 128k -y
testTrim.mp4
ffmpeg version 2.3.git Copyright (c) 2000-2014 the FFmpeg developers
built on Aug 7 2014 18:14:20 with gcc 4.6 (Ubuntu/Linaro
4.6.3-1ubuntu5)
configuration: --prefix=/home/stuzzo/ffmpeg_build
--extra-cflags=-I/home/stuzzo/ffmpeg_build/include
--extra-ldflags=-L/home/stuzzo/ffmpeg_build/lib
--bindir=/home/stuzzo/bin --extra-libs=-ldl --enable-gpl --enable-libass
--enable-libfdk-aac --enable-libmp3lame --enable-libopus
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libxvid
--enable-libx264 --enable-nonfree
libavutil 52. 98.100 / 52. 98.100
libavcodec 55. 72.102 / 55. 72.102
libavformat 55. 51.101 / 55. 51.101
libavdevice 55. 13.102 / 55. 13.102
libavfilter 4. 11.102 / 4. 11.102
libswscale 2. 6.100 / 2. 6.100
libswresample 0. 19.100 / 0. 19.100
libpostproc 52. 3.100 / 52. 3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'sample.mov':
Metadata:
major_brand : qt
minor_version : 537199360
compatible_brands: qt
creation_time : 2005-10-17 22:54:32
Duration: 00:01:25.50, start: 0.000000, bitrate: 307 kb/s
Stream #0:0(eng): Video: mpeg4 (Simple Profile) (mp4v /
0x7634706D), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 261 kb/s, 10 fps, 10
tbr, 3k tbn, 25 tbc (default)
Metadata:
creation_time : 2005-10-17 22:54:33
handler_name : Apple Video Media Handler
encoder : 3ivx D4 4.5.1
Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 32000 Hz,
mono, fltp, 43 kb/s (default)
Metadata:
creation_time : 2005-10-17 22:54:34
handler_name : Apple Sound Media Handler
[libx264 @ 0x2ad0620] using SAR=1/1
[libx264 @ 0x2ad0620] using cpu capabilities: MMX2 SSE2Fast SSSE3
SSE4.2 AVX
[libx264 @ 0x2ad0620] profile Main, level 3.1
[libx264 @ 0x2ad0620] 264 - core 142 - H.264/MPEG-4 AVC codec -
Copyleft 2003-2014 - http://www.videolan.org/x264.html - options:
cabac=1 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1
psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=0
cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12
lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0
bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1
b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250
keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf
mbtree=1 crf=20.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=1200
vbv_bufsize=1835 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'testTrim.mp4':
Metadata:
major_brand : qt
minor_version : 537199360
compatible_brands: qt
encoder : Lavf55.51.101
Stream #0:0(eng): Video: h264 (libx264) ([33][0][0][0] /
0x0021), yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=-1--1, 1200 kb/s, 25 fps,
12800 tbn, 25 tbc (default)
Metadata:
creation_time : 2005-10-17 22:54:33
handler_name : Apple Video Media Handler
encoder : Lavc55.72.102 libx264
Stream #0:1(eng): Audio: aac (libfdk_aac) ([64][0][0][0] /
0x0040), 48000 Hz, stereo, s16, 128 kb/s (default)
Metadata:
creation_time : 2005-10-17 22:54:34
handler_name : Apple Sound Media Handler
encoder : Lavc55.72.102 libfdk_aac
Stream mapping:
Stream #0:0 -> #0:0 (mpeg4 (native) -> h264 (libx264))
Stream #0:1 -> #0:1 (aac (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame= 149 fps=0.0 q=-1.0 Lsize= 122kB time=00:00:06.01
bitrate= 165.5kbits/s dup=89 drop=0
video:21kB audio:95kB subtitle:0kB other streams:0kB global
headers:0kB muxing overhead: 4.938407%
[libx264 @ 0x2ad0620] frame I:1 Avg QP: 8.65 size: 425
[libx264 @ 0x2ad0620] frame P:42 Avg QP: 9.92 size: 347
[libx264 @ 0x2ad0620] frame B:106 Avg QP: 9.92 size: 56
[libx264 @ 0x2ad0620] consecutive B-frames: 4.7% 1.3% 0.0% 94.0%
[libx264 @ 0x2ad0620] mb I I16..4: 98.8% 0.0% 1.2%
[libx264 @ 0x2ad0620] mb P I16..4: 1.3% 0.0% 0.5% P16..4:
1.2% 0.4% 0.3% 0.0% 0.0% skip:96.3%
[libx264 @ 0x2ad0620] mb B I16..4: 0.1% 0.0% 0.0% B16..8:
2.1% 0.0% 0.0% direct: 0.0% skip:97.8% L0:26.8% L1:73.2% BI: 0.1%
[libx264 @ 0x2ad0620] coded y,uvDC,uvAC intra: 11.0% 2.5% 0.6%
inter: 0.1% 0.1% 0.0%
[libx264 @ 0x2ad0620] i16 v,h,dc,p: 60% 39% 0% 0%
[libx264 @ 0x2ad0620] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 27% 42% 17%
2% 2% 3% 3% 3% 2%
[libx264 @ 0x2ad0620] i8c dc,h,v,p: 83% 15% 2% 0%
[libx264 @ 0x2ad0620] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x2ad0620] ref P L0: 82.2% 5.1% 10.5% 2.2%
[libx264 @ 0x2ad0620] ref B L0: 56.4% 43.6%
[libx264 @ 0x2ad0620] ref B L1: 99.4% 0.6%
[libx264 @ 0x2ad0620] kb/s:28.08
Thank you
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