我正在尝试使用ffmpeg使用不同的恒定帧速率对视频进行编码。输出文件的持续时间与原始文件的持续时间相差0.02秒（大约一帧）。
如何在不更改持续时间的情况下更改帧速率。
我正在使用此命令：“ ffmpeg.exe -y -i work.ts -an -c：v libx264 -pix_fmt yuv420p -s 1280x720 -framerate 29.97 out.ts”
原始帧率为：59.94 fps
任何帮助将不胜感激:-)
日志：
ffmpeg.exe -y -i work.ts -an -c:v libx264 -pix_fmt yuv420p -s 1280x720 -framerate 29.97 out.ts
ffmpeg version 3.4.1 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 7.2.0 (GCC)
configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
libavutil 55. 78.100 / 55. 78.100
libavcodec 57.107.100 / 57.107.100
libavformat 57. 83.100 / 57. 83.100
libavdevice 57. 10.100 / 57. 10.100
libavfilter 6.107.100 / 6.107.100
libswscale 4. 8.100 / 4. 8.100
libswresample 2. 9.100 / 2. 9.100
libpostproc 54. 7.100 / 54. 7.100
Input #0, mpegts, from 'work.ts':
Duration: 00:00:04.02, start: 31.405178, bitrate: 6430 kb/s
Program 1
Metadata:
service_name : Service01
service_provider: FFmpeg
Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720, 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc
Stream #0:1[0x101](und): Audio: aac (LC) ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 126 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0000024c3c135a00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0000024c3c135a00] profile High, level 3.2
Output #0, mpegts, to 'out.ts':
Metadata:
encoder : Lavf57.83.100
Stream #0:0: Video: h264 (libx264), yuv420p, 1280x720, q=-1--1, 59.94 fps, 90k tbn, 59.94 tbc
Metadata:
encoder : Lavc57.107.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
frame= 240 fps= 43 q=-1.0 Lsize= 2120kB time=00:00:03.95 bitrate=4391.5kbits/s speed=0.714x
video:1940kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 9.278002%
[libx264 @ 0000024c3c135a00] frame I:1 Avg QP:27.60 size: 71877
[libx264 @ 0000024c3c135a00] frame P:61 Avg QP:28.06 size: 22993
[libx264 @ 0000024c3c135a00] frame B:178 Avg QP:31.75 size: 2875
[libx264 @ 0000024c3c135a00] consecutive B-frames: 0.8% 0.8% 0.0% 98.3%
[libx264 @ 0000024c3c135a00] mb I I16..4: 5.0% 11.6% 83.5%
[libx264 @ 0000024c3c135a00] mb P I16..4: 2.5% 3.6% 4.7% P16..4: 43.1% 20.1% 10.1% 0.0% 0.0% skip:15.9%
[libx264 @ 0000024c3c135a00] mb B I16..4: 0.2% 0.1% 0.2% B16..8: 22.6% 2.9% 0.5% direct: 0.6% skip:73.1% L0:33.7% L1:59.3% BI: 6.9%
[libx264 @ 0000024c3c135a00] 8x8 transform intra:29.6% inter:65.2%
[libx264 @ 0000024c3c135a00] coded y,uvDC,uvAC intra: 68.8% 68.1% 30.0% inter: 10.8% 9.5% 0.4%
[libx264 @ 0000024c3c135a00] i16 v,h,dc,p: 10% 80% 5% 6%
[libx264 @ 0000024c3c135a00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 11% 49% 14% 4% 3% 4% 4% 5% 7%
[libx264 @ 0000024c3c135a00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 12% 55% 10% 3% 3% 4% 4% 3% 5%
[libx264 @ 0000024c3c135a00] i8c dc,h,v,p: 42% 35% 15% 7%
[libx264 @ 0000024c3c135a00] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0000024c3c135a00] ref P L0: 69.3% 16.2% 11.6% 2.8%
[libx264 @ 0000024c3c135a00] ref B L0: 88.4% 8.8% 2.8%
[libx264 @ 0000024c3c135a00] ref B L1: 99.4% 0.6%
[libx264 @ 0000024c3c135a00] kb/s:3968.40
ffProbe\ffprobe.exe work.ts
ffprobe version N-82117-gc117343 Copyright (c) 2007-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
libavutil 55. 33.100 / 55. 33.100
libavcodec 57. 63.103 / 57. 63.103
libavformat 57. 55.100 / 57. 55.100
libavdevice 57. 0.103 / 57. 0.103
libavfilter 6. 64.100 / 6. 64.100
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 2.100 / 2. 2.100
libpostproc 54. 0.100 / 54. 0.100
Input #0, mpegts, from 'work.ts':
Duration: 00:00:04.02, start: 31.405178, bitrate: 6430 kb/s
Program 1
Metadata:
service_name : Service01
service_provider: FFmpeg
Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720, 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc
Stream #0:1[0x101](und): Audio: aac (LC) ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 126 kb/s
ffProbe\ffprobe.exe out.ts
ffprobe version N-82117-gc117343 Copyright (c) 2007-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
libavutil 55. 33.100 / 55. 33.100
libavcodec 57. 63.103 / 57. 63.103
libavformat 57. 55.100 / 57. 55.100
libavdevice 57. 0.103 / 57. 0.103
libavfilter 6. 64.100 / 6. 64.100
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 2.100 / 2. 2.100
libpostproc 54. 0.100 / 54. 0.100
Input #0, mpegts, from 'out.ts':
Duration: 00:00:04.00, start: 1.433367, bitrate: 4336 kb/s
Program 1
Metadata:
service_name : Service01
service_provider: FFmpeg
Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(progressive), 1280x720, 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc
如果原始视频的帧数为奇数，并且您将其重新编码为帧速率的一半，则不可能达到与原始视频完全相同的长度。您可以或多或少地在半帧（新帧速率）之间进行选择。
默认情况下ffmpeg将选择较长的版本，但是通过设置“ -t ss.sss”，您可以强制使用较短的版本。
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