我想通过ffmpeg创建一个带有背景音乐的幻灯片，并使用命令
ffmpeg -f concat -safe 0 -i map.txt -i audio.flac -vsync vfr -pix_fmt yuv420p -strict -2 video.mp4
和map.txt类似
file '1.jpg'
duration 15
file '2.jpg'
duration 60
结果是带有音频和空白背景的视频。如果我在没有音频的情况下运行上述命令
ffmpeg -f concat -safe 0 -i map.txt -pix_fmt yuv420p -strict -2 video.mp4
生成完美的图像视频（预期的幻灯片）（但显然没有音频）。
我认为问题与同步音频和图像有关。
这是第一个命令的终端输出
ffmpeg -f concat -safe 0 -i map.txt -i audio.flac -vsync vfr -pix_fmt yuv420p -strict -2 video.mp4
ffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
libavutil 54. 31.100 / 54. 31.100
libavcodec 56. 60.100 / 56. 60.100
libavformat 56. 40.101 / 56. 40.101
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 40.101 / 5. 40.101
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 2.101 / 1. 2.101
libpostproc 53. 3.100 / 53. 3.100
[mjpeg @ 0x1cc8d40] Changeing bps to 8
Input #0, concat, from 'map.txt':
Duration: 00:05:48.00, start: 0.000000, bitrate: 0 kb/s
Stream #0:0: Video: mjpeg, gray(bt470bg/unknown/unknown), 1920x1080 [SAR 72:72 DAR 16:9], 25 tbr, 25 tbn, 25 tbc
Input #1, flac, from 'audio.flac':
Metadata:
TITLE : Speak to Me
ARTIST : Creator
ALBUM : Acoustic Hits
track : 14
GENRE : Pop
DATE : 2011
Duration: 00:03:31.02, start: 0.000000, bitrate: 1026 kb/s
Stream #1:0: Audio: flac, 44100 Hz, stereo, s16
[libx264 @ 0x1ccdf80] using SAR=1/1
[libx264 @ 0x1ccdf80] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
[libx264 @ 0x1ccdf80] profile High, level 4.0
[libx264 @ 0x1ccdf80] 264 - core 148 r2643 5c65704 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - 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=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=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'video.mp4':
Metadata:
encoder : Lavf56.40.101
Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 25 fps, 12800 tbn, 25 tbc
Metadata:
encoder : Lavc56.60.100 libx264
Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 44100 Hz, stereo, fltp (16 bit), 128 kb/s
Metadata:
encoder : Lavc56.60.100 aac
Stream mapping:
Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (flac (native) -> aac (native))
Press [q] to stop, [?] for help
[mjpeg @ 0x7fe688001ba0] Changeing bps to 8
frame= 2 fps=0.7 q=-1.0 Lsize= 3593kB time=00:03:31.02 bitrate= 139.5kbits/s
video:147kB audio:3410kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.036417%
[libx264 @ 0x1ccdf80] frame I:1 Avg QP: 2.55 size: 33683
[libx264 @ 0x1ccdf80] frame P:1 Avg QP:19.33 size:116022
[libx264 @ 0x1ccdf80] mb I I16..4: 89.7% 1.1% 9.3%
[libx264 @ 0x1ccdf80] mb P I16..4: 0.9% 1.8% 30.1% P16..4: 1.4% 1.5% 0.9% 0.0% 0.0% skip:63.4%
[libx264 @ 0x1ccdf80] 8x8 transform intra:2.1% inter:15.2%
[libx264 @ 0x1ccdf80] coded y,uvDC,uvAC intra: 19.7% 0.0% 0.0% inter: 2.8% 0.0% 0.0%
[libx264 @ 0x1ccdf80] i16 v,h,dc,p: 97% 2% 2% 0%
[libx264 @ 0x1ccdf80] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 37% 12% 39% 1% 1% 2% 1% 2% 4%
[libx264 @ 0x1ccdf80] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 43% 16% 16% 3% 4% 6% 5% 5% 4%
[libx264 @ 0x1ccdf80] i8c dc,h,v,p: 100% 0% 0% 0%
[libx264 @ 0x1ccdf80] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x1ccdf80] kb/s:20.65
更新（在评论建议之后）
ffmpeg -f concat -safe 0 -i map.txt -i audio.flac -vsync vfr -r 5 -pix_fmt yuv420p -strict -2 video.mp4
ffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
libavutil 54. 31.100 / 54. 31.100
libavcodec 56. 60.100 / 56. 60.100
libavformat 56. 40.101 / 56. 40.101
libavdevice 56. 4.100 / 56. 4.100
libavfilter 5. 40.101 / 5. 40.101
libavresample 2. 1. 0 / 2. 1. 0
libswscale 3. 1.101 / 3. 1.101
libswresample 1. 2.101 / 1. 2.101
libpostproc 53. 3.100 / 53. 3.100
[mjpeg @ 0x1fe9d80] Changeing bps to 8
Input #0, concat, from 'map.txt':
Duration: 00:02:28.00, start: 0.000000, bitrate: 0 kb/s
Stream #0:0: Video: mjpeg, gray(bt470bg/unknown/unknown), 1920x1080 [SAR 72:72 DAR 16:9], 25 tbr, 25 tbn, 25 tbc
Input #1, flac, from 'audio.flac':
Metadata:
TITLE : Speak to Me
ARTIST : Creator
ALBUM : Acoustic Hits
track : 14
GENRE : Pop
DATE : 2011
Duration: 00:03:31.02, start: 0.000000, bitrate: 1026 kb/s
Stream #1:0: Audio: flac, 44100 Hz, stereo, s16
[libx264 @ 0x1feefc0] using SAR=1/1
[libx264 @ 0x1feefc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
[libx264 @ 0x1feefc0] profile High, level 4.0
[libx264 @ 0x1feefc0] 264 - core 148 r2643 5c65704 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - 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=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=5 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to 'video.mp4':
Metadata:
encoder : Lavf56.40.101
Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=-1--1, 5 fps, 10240 tbn, 5 tbc
Metadata:
encoder : Lavc56.60.100 libx264
Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 44100 Hz, stereo, fltp (16 bit), 128 kb/s
Metadata:
encoder : Lavc56.60.100 aac
Stream mapping:
Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
Stream #1:0 -> #0:1 (flac (native) -> aac (native))
Press [q] to stop, [?] for help
[mjpeg @ 0x7f74cc001ba0] Changeing bps to 8
frame= 2 fps=0.7 q=-1.0 Lsize= 3593kB time=00:03:31.02 bitrate= 139.5kbits/s
video:147kB audio:3410kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.036417%
[libx264 @ 0x1feefc0] frame I:1 Avg QP: 2.55 size: 33683
[libx264 @ 0x1feefc0] frame P:1 Avg QP:19.33 size:116022
[libx264 @ 0x1feefc0] mb I I16..4: 89.7% 1.1% 9.3%
[libx264 @ 0x1feefc0] mb P I16..4: 0.9% 1.8% 30.1% P16..4: 1.4% 1.5% 0.9% 0.0% 0.0% skip:63.4%
[libx264 @ 0x1feefc0] 8x8 transform intra:2.1% inter:15.2%
[libx264 @ 0x1feefc0] coded y,uvDC,uvAC intra: 19.7% 0.0% 0.0% inter: 2.8% 0.0% 0.0%
[libx264 @ 0x1feefc0] i16 v,h,dc,p: 97% 2% 2% 0%
[libx264 @ 0x1feefc0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 37% 12% 39% 1% 1% 2% 1% 2% 4%
[libx264 @ 0x1feefc0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 43% 16% 16% 3% 4% 6% 5% 5% 4%
[libx264 @ 0x1feefc0] i8c dc,h,v,p: 100% 0% 0% 0%
[libx264 @ 0x1feefc0] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0x1feefc0] kb/s:20.65