[FFmpeg-user] ffmpeg timestamps, offsets, and frame count
S Andreason
sandreas41 at gmail.com
Sat Feb 1 21:37:37 EET 2020
S Andreason wrote:
> 1. frame# as n, or at playback and pressing the keys for back to
> beginning, does not start until 0.566 for frame # 0 because (I think)
> the source video has an audio offset. This makes problem#1 affect all
> future edits.
>
> 2. How can I override the timing, and just copy frame by frame
> ignoring the timestamps of [1]?
>
Perhaps if I supply sample files... here is a sample source video from
the camera in question.
https://www.seahorsecorral.org/videos/tests/20190628_163959_driving-WCurlewLkRd-S_30sec_FHDw.MOV
https://www.seahorsecorral.org/videos/tests/redwave-500x400.gif
I have also recompiled latest git with no change.
Step 1. clip desired video. I want to start at 22.0 seconds, (where the
blue sign is visible on left) but the nearest I-frame appears to be at
21.933 sec according to mpv.
$ ffprobe -show_frames says 21.566 for nearest pict_type=I
Giving a -ss 22 or -ss 21.97 results in a 0.566 gap in video, where the
audio is not cut at the same place as the video, so it was not cut at
the I-frame.
-ss 21.933 results in a 0.114 sec gap.
-ss 21.566 results in a 0.497 sec gap.
-ss 21.96 results in 0.092 sec gap, which seems to be the best I can
get. Too many of these concat together later will result in audio sync
problems, so there is a good reason to ask how to improve the cut here.
$ ffmpeg -i 20190628_163959_driving-WCurlewLkRd-S_30sec_FHDw.MOV -ss
21.96 -t 6 -c copy
20190628_163959_driving-WCurlewLkRd-S_30sec_FHDw_c21.96t6.MOV
ffmpeg version N-96573-g73aab08d9d Copyright (c) 2000-2020 the FFmpeg
developers
built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
configuration: --prefix=/usr/local --enable-gpl --enable-libmp3lame
--enable-libvorbis --enable-libx264 --enable-libopenjpeg
--enable-libfreetype --disable-doc --disable-htmlpages
--disable-podpages --enable-shared --enable-libvpx
--extra-cflags=-I/usr/include --extra-ldflags=-L/usr/lib/i386-linux-gnu
--enable-libass --enable-libtesseract --extra-cflags=-msse2
--enable-openssl --enable-nonfree
libavutil 56. 38.100 / 56. 36.101
libavcodec 58. 67.100 / 58. 64.101
libavformat 58. 37.100 / 58. 35.101
libavdevice 58. 9.103 / 58. 9.101
libavfilter 7. 72.100 / 7. 68.100
libswscale 5. 6.100 / 5. 6.100
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x1569540] st: 0 edit list: 1 Missing key
frame while searching for timestamp: 2000
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x1569540] st: 0 edit list 1 Cannot find an
index entry before timestamp: 2000.
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
'20190628_163959_driving-WCurlewLkRd-S_30sec_FHDw.MOV':
Metadata:
major_brand : qt
minor_version : 0
compatible_brands: qt
creation_time : 2019-06-28T16:39:59.000000Z
playback_requirements: QuickTime 6.0 or greater
playback_requirements-eng: QuickTime 6.0 or greater
Duration: 00:00:29.50, start: 0.000000, bitrate: 15212 kb/s
Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
1920x1080, 15078 kb/s, 30 fps, 30 tbr, 60k tbn, 120k tbc (default)
Metadata:
creation_time : 2019-06-28T16:39:59.000000Z
handler_name : Video Handler
encoder : iCatch AVCC
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
stereo, fltp, 127 kb/s (default)
Metadata:
creation_time : 2019-06-28T16:39:59.000000Z
handler_name : Audio Handler
Output #0, mov, to
'20190628_163959_driving-WCurlewLkRd-S_30sec_FHDw_c21.96t6.MOV':
Metadata:
major_brand : qt
minor_version : 0
compatible_brands: qt
playback_requirements-eng: QuickTime 6.0 or greater
playback_requirements: QuickTime 6.0 or greater
encoder : Lavf58.35.101
Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
1920x1080, q=2-31, 15078 kb/s, 30 fps, 30 tbr, 60k tbn, 60k tbc (default)
Metadata:
creation_time : 2019-06-28T16:39:59.000000Z
handler_name : Video Handler
encoder : iCatch AVCC
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
stereo, fltp, 127 kb/s (default)
Metadata:
creation_time : 2019-06-28T16:39:59.000000Z
handler_name : Audio Handler
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame= 180 fps=0.0 q=-1.0 Lsize= 10873kB time=00:00:05.98
bitrate=14878.9kbits/s speed=74.4x
video:10772kB audio:94kB subtitle:0kB other streams:0kB global
headers:0kB muxing overhead: 0.068655%
Step 2 add gif and show n
$ ffmpeg -i
20190628_163959_driving-WCurlewLkRd-S_30sec_FHDw_c21.96t6.MOV
-ignore_loop 0 -i redwave-500x400.gif -filter_complex
"[0]scale=1280x720,drawtext='fontfile=/usr/share/fonts/TrueType/lsansd.ttf:text=%{n}:x=(w-tw)/2:y=h-(2*lh):fontcolor=white:box=1:boxcolor=0x00000099'[0st],[0st][1]overlay=x=(570+(n*6)):y=10:enable=between(n\,30\,120)"
-s 1280x720 -c:v h264 -b:v 4700k -r 30 -t 6
CurlewLk_c216t6-red_30-120-720e.mov
ffmpeg version N-96573-g73aab08d9d Copyright (c) 2000-2020 the FFmpeg
developers
built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
configuration: --prefix=/usr/local --enable-gpl --enable-libmp3lame
--enable-libvorbis --enable-libx264 --enable-libopenjpeg
--enable-libfreetype --disable-doc --disable-htmlpages
--disable-podpages --enable-shared --enable-libvpx
--extra-cflags=-I/usr/include --extra-ldflags=-L/usr/lib/i386-linux-gnu
--enable-libass --enable-libtesseract --extra-cflags=-msse2
--enable-openssl --enable-nonfree
libavutil 56. 38.100 / 56. 36.101
libavcodec 58. 67.100 / 58. 64.101
libavformat 58. 37.100 / 58. 35.101
libavdevice 58. 9.103 / 58. 9.101
libavfilter 7. 72.100 / 7. 68.100
libswscale 5. 6.100 / 5. 6.100
libswresample 3. 6.100 / 3. 6.100
libpostproc 55. 6.100 / 55. 6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from
'20190628_163959_driving-WCurlewLkRd-S_30sec_FHDw_c21.96t6.MOV':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf58.35.101
Duration: 00:00:06.00, start: 0.013000, bitrate: 14845 kb/s
Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
1920x1080, 14707 kb/s, 30 fps, 30 tbr, 60k tbn, 120k tbc (default)
Metadata:
handler_name : Video Handler
encoder : iCatch AVCC
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
stereo, fltp, 127 kb/s (default)
Metadata:
handler_name : Audio Handler
Input #1, gif, from 'redwave-500x400.gif':
Duration: 00:00:01.35, start: 0.000000, bitrate: 2635 kb/s
Stream #1:0: Video: gif, bgra, 500x400, 34 fps, 100 tbr, 100 tbn,
100 tbc
Stream mapping:
Stream #0:0 (h264) -> scale (graph 0)
Stream #1:0 (gif) -> overlay:overlay (graph 0)
overlay (graph 0) -> Stream #0:0 (libx264)
Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x1ac8d40] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2
AVX LZCNT BMI1 SlowPshufb
[libx264 @ 0x1ac8d40] profile High, level 3.1
[libx264 @ 0x1ac8d40] 264 - core 148 r2748 97eaef2 - H.264/MPEG-4 AVC
codec - Copyleft 2003-2016 - http://www.videolan.org/x264.html -
options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7
psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1
8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6
lookahead_threads=1 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=abr
mbtree=1 bitrate=4700 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4
ip_ratio=1.40 aq=1:1.00
Output #0, mov, to 'CurlewLk_c216t6-red_30-120-720e.mov':
Metadata:
major_brand : qt
minor_version : 512
compatible_brands: qt
encoder : Lavf58.35.101
Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p,
1280x720, q=-1--1, 4700 kb/s, 30 fps, 15360 tbn, 30 tbc (default)
Metadata:
encoder : Lavc58.67.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/4700000 buffer size: 0 vbv_delay: N/A
Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
stereo, fltp, 128 kb/s (default)
Metadata:
handler_name : Audio Handler
encoder : Lavc58.67.100 aac
frame= 180 fps=9.2 q=-1.0 Lsize= 2921kB time=00:00:05.99
bitrate=3991.5kbits/s dup=3 drop=0 speed=0.308x
video:2819kB audio:94kB subtitle:0kB other streams:0kB global
headers:0kB muxing overhead: 0.270207%
[libx264 @ 0x1ac8d40] frame I:1 Avg QP:16.49 size:136468
[libx264 @ 0x1ac8d40] frame P:45 Avg QP:23.47 size: 27882
[libx264 @ 0x1ac8d40] frame B:134 Avg QP:26.75 size: 11154
[libx264 @ 0x1ac8d40] consecutive B-frames: 0.6% 0.0% 1.7% 97.8%
[libx264 @ 0x1ac8d40] mb I I16..4: 6.2% 58.4% 35.4%
[libx264 @ 0x1ac8d40] mb P I16..4: 1.3% 6.8% 2.1% P16..4: 44.2%
16.8% 10.0% 0.0% 0.0% skip:18.8%
[libx264 @ 0x1ac8d40] mb B I16..4: 0.1% 0.9% 0.4% B16..8: 41.1%
6.5% 2.4% direct: 2.1% skip:46.5% L0:43.7% L1:48.2% BI: 8.1%
[libx264 @ 0x1ac8d40] final ratefactor: 20.29
[libx264 @ 0x1ac8d40] 8x8 transform intra:64.4% inter:68.0%
[libx264 @ 0x1ac8d40] coded y,uvDC,uvAC intra: 82.4% 80.6% 41.9% inter:
17.5% 21.8% 3.4%
[libx264 @ 0x1ac8d40] i16 v,h,dc,p: 3% 48% 4% 45%
[libx264 @ 0x1ac8d40] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 10% 22% 17% 6% 8%
7% 9% 6% 14%
[libx264 @ 0x1ac8d40] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 12% 26% 15% 7% 9%
7% 10% 6% 9%
[libx264 @ 0x1ac8d40] i8c dc,h,v,p: 50% 31% 10% 9%
[libx264 @ 0x1ac8d40] Weighted P-Frames: Y:6.7% UV:4.4%
[libx264 @ 0x1ac8d40] ref P L0: 53.1% 16.7% 21.6% 8.2% 0.3%
[libx264 @ 0x1ac8d40] ref B L0: 83.3% 13.4% 3.3%
[libx264 @ 0x1ac8d40] ref B L1: 91.1% 8.9%
[libx264 @ 0x1ac8d40] kb/s:3847.67
[aac @ 0x1ab7600] Qavg: 222.272
Notice frame 1 overlay doesn't start at 0.0 I really need frame 0 to be
0 for all later calculations to work without adding offsets.
Notice the gif frame starts at 24 or 0.900 sec.
Notice the last gif frame is 105 at 3.600 sec.
I can work around this limitation (unless you have a solution) by
recalculating the start and stop points for n. x/30/0.03=n
I can't duplicate problem 3 on such a short file, so let's focus on the
above questions.
Thank you, Stewart
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