将 ffmpeg filter_complex 中具有不同时基的视频转换为使用 xfade

Question

我想使用 ffmpeg 的新 xfade 过滤器在两个视频之间交叉淡入淡出。理论上这很容易：

ffmpeg -i v1.mp4 -i v2.mp4 \
  -filter_complex "[0][1]xfade=duration=1:offset=5,format=yuv420p" \
  out.mp4

但是，这会失败并出现错误：

First input link main timebase (1/1500) do not match the corresponding second input link xfade timebase (1/30000)

显然，这两个视频确实有不同的时基。 ffmpeg 输出证实了这一点：

Stream #0:0(eng): Video: h264 (High 4:4:4 Predictive) (avc1 / 0x31637661), yuv444p, 1280x720 [SAR 1:1 DAR 16:9], 536 kb/s, 15 fps, 15 tbr, 1500 tbn, 30 tbc (default)
...
Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/unknown/bt709), 1280x720 [SAR 1:1 DAR 16:9], 1117 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)

我不想转换每个视频并保存结果，然后然后合并两个新的临时磁盘文件。是否可以使用-filter_complex 转换xfade 之前的视频，使它们具有相同的时基？这样我就可以运行一个命令来获取任意两个视频并在它们之间进行淡入淡出吗？

尝试使用 settb 过滤器显式设置时基一开始似乎可行，但随后“卡在”第 3 帧，再也没有取得任何进展：

$ ffmpeg -i v1.mp4 -i v2.mp4 -filter_complex "[0]settb=1/AVTB[v0];[1]settb=1/AVTB[v1];[v0][v1]xfade=duration=1:offset=5,format=yuv420p" out.mp4
ffmpeg version N-53546-g5eb4405fc5-static https://johnvansickle.com/ffmpeg/  Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 8 (Debian 8.3.0-6)
  configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gmp --enable-libgme --enable-gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libdav1d --enable-libxvid --enable-libzvbi --enable-libzimg
  libavutil      56. 56.100 / 56. 56.100
  libavcodec     58. 97.100 / 58. 97.100
  libavformat    58. 49.100 / 58. 49.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 87.100 /  7. 87.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'v1.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42mp41isomiso2
    creation_time   : 2014-08-20T20:47:56.000000Z
    encoder         : x264
  Duration: 00:00:12.67, start: 0.000000, bitrate: 538 kb/s
    Stream #0:0(eng): Video: h264 (High 4:4:4 Predictive) (avc1 / 0x31637661), yuv444p, 1280x720 [SAR 1:1 DAR 16:9], 536 kb/s, 15 fps, 15 tbr, 1500 tbn, 30 tbc (default)
    Metadata:
      creation_time   : 2014-08-20T20:47:56.000000Z
      handler_name    : VideoHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'v2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.83.100
  Duration: 00:00:04.31, start: 0.000000, bitrate: 1286 kb/s
    Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709/unknown/bt709), 1280x720 [SAR 1:1 DAR 16:9], 1117 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 159 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
File 'out.mp4' already exists. Overwrite? [y/N] y
Stream mapping:
  Stream #0:0 (h264) -> settb (graph 0)
  Stream #1:0 (h264) -> settb (graph 0)
  format (graph 0) -> Stream #0:0 (libx264)
  Stream #1:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x69aaac0] using SAR=1/1
[libx264 @ 0x69aaac0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x69aaac0] profile High, level 3.1, 4:2:0, 8-bit
[libx264 @ 0x69aaac0] 264 - core 161 r3018 db0d417 - H.264/MPEG-4 AVC codec - Copyleft 2003-2020 - 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=15 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 'out.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42mp41isomiso2
    encoder         : Lavf58.49.100
    Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 15 fps, 15360 tbn, 15 tbc (default)
    Metadata:
      encoder         : Lavc58.97.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      encoder         : Lavc58.97.100 aac
frame=    3 fps=0.0 q=0.0 size=       0kB time=00:00:02.94 bitrate=   0.1kbits/s
frame=    3 fps=3.0 q=0.0 size=       0kB time=00:00:04.24 bitrate=   0.1kbits/s
frame=    3 fps=2.0 q=0.0 size=       0kB time=00:00:04.24 bitrate=   0.1kbits/s
frame=    3 fps=1.5 q=0.0 size=       0kB time=00:00:04.24 bitrate=   0.1kbits/s
(and repeat this line forever)

Answer 1

您可以使用settb过滤器来设置一个普通的TB。

ffmpeg -i v1.mp4 -i v2.mp4 \
  -filter_complex "[0]settb=AVTB[v0];[1]settb=AVTB[v1];\
                   [v0][v1]xfade=duration=1:offset=5,format=yuv420p" \
  out.mp4