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• ffmpeg xfade audio out of sync

  1er décembre 2020, par Richard

  hi I am using ffmpeg xfade to concat two clips, the transition looks fine, but the second clip has no audio in the output. I don't find more information about this in https://trac.ffmpeg.org/wiki/Xfade and the official doc. Can I keep the audio of both clips in sync ?

  


  I'm puttting the complete log below, it's massive

  


  ffmpeg -i teacher1.mp4 -i teacher2.mp4 -filter_complex xfade=transition=fadewhite:duration=1:offset=14.5 output.mp4
ffmpeg version 4.3.1-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. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'teacher1.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.29.100
  Duration: 00:00:15.02, start: 0.000000, bitrate: 2447 kb/s
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 2315 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'teacher2.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.29.100
  Duration: 00:00:15.02, start: 0.000000, bitrate: 1643 kb/s
    Stream #1:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 1509 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)
    Metadata:
      handler_name    : VideoHandler
    Stream #1:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
Stream mapping:
  Stream #0:0 (h264) -> xfade:main (graph 0)
  Stream #1:0 (h264) -> xfade:xfade (graph 0)
  xfade (graph 0) -> Stream #0:0 (libx264)
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x64603c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x64603c0] profile High 4:4:4 Predictive, level 4.0, 4:4:4, 8-bit
[libx264 @ 0x64603c0] 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=4 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=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 'output.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf58.45.100
    Stream #0:0: Video: h264 (libx264) (avc1 / 0x31637661), yuv444p, 1920x1080, q=-1--1, 25 fps, 12800 tbn, 25 tbc (default)
    Metadata:
      encoder         : Lavc58.91.100 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), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      encoder         : Lavc58.91.100 aac
frame=  738 fps= 25 q=-1.0 Lsize=    7317kB time=00:00:29.40 bitrate=2038.9kbits/s speed=1.01x    
video:7064kB audio:236kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.241368%
[libx264 @ 0x64603c0] frame I:8     Avg QP:16.56  size:100307
[libx264 @ 0x64603c0] frame P:332   Avg QP:19.50  size: 15211
[libx264 @ 0x64603c0] frame B:398   Avg QP:24.35  size:  3467
[libx264 @ 0x64603c0] consecutive B-frames:  6.2% 62.6%  8.9% 22.2%
[libx264 @ 0x64603c0] mb I  I16..4: 18.7% 60.5% 20.9%
[libx264 @ 0x64603c0] mb P  I16..4:  4.5%  7.6%  0.6%  P16..4: 24.1%  5.6%  1.9%  0.0%  0.0%    skip:55.7%
[libx264 @ 0x64603c0] mb B  I16..4:  0.4%  0.5%  0.1%  B16..8: 14.3%  0.9%  0.1%  direct: 0.4%  skip:83.3%  L0:42.9% L1:53.9% BI: 3.3%
[libx264 @ 0x64603c0] 8x8 transform intra:59.2% inter:84.3%
[libx264 @ 0x64603c0] coded y,u,v intra: 25.3% 11.9% 13.0% inter: 3.2% 1.7% 1.8%
[libx264 @ 0x64603c0] i16 v,h,dc,p: 49% 25% 15% 12%
[libx264 @ 0x64603c0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 31% 17% 37%  2%  2%  3%  2%  3%  2%
[libx264 @ 0x64603c0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 28% 19% 15%  6%  7%  7%  6%  6%  5%
[libx264 @ 0x64603c0] Weighted P-Frames: Y:3.3% UV:1.5%
[libx264 @ 0x64603c0] ref P L0: 66.0%  8.0% 18.5%  7.5%  0.0%
[libx264 @ 0x64603c0] ref B L0: 84.9% 13.1%  2.0%
[libx264 @ 0x64603c0] ref B L1: 98.8%  1.2%
[libx264 @ 0x64603c0] kb/s:1960.04
[aac @ 0x64d1280] Qavg: 171.394


  


• aarch64 : vp9 : Add NEON itxfm routines

  14 novembre 2016, par Martin Storsjö

  aarch64 : vp9 : Add NEON itxfm routines
  This work is sponsored by, and copyright, Google.
  These are ported from the ARM version ; thanks to the larger
  
  amount of registers available, we can do the 16x16 and 32x32
  
  transforms in slices 8 pixels wide instead of 4. This gives
  
  a speedup of around 1.4x compared to the 32 bit version.
  The fact that aarch64 doesn’t have the same d/q register
  
  aliasing makes some of the macros quite a bit simpler as well.
  Examples of runtimes vs the 32 bit version, on a Cortex A53 :
  
                                         ARM  AArch64
  
  vp9_inv_adst_adst_4x4_add_neon :       90.0     87.7
  
  vp9_inv_adst_adst_8x8_add_neon :      400.0    354.7
  
  vp9_inv_adst_adst_16x16_add_neon :   2526.5   1827.2
  
  vp9_inv_dct_dct_4x4_add_neon :         74.0     72.7
  
  vp9_inv_dct_dct_8x8_add_neon :        271.0    256.7
  
  vp9_inv_dct_dct_16x16_add_neon :     1960.7   1372.7
  
  vp9_inv_dct_dct_32x32_add_neon :    11988.9   8088.3
  
  vp9_inv_wht_wht_4x4_add_neon :         63.0     57.7
  The speedup vs C code (2-4x) is smaller than in the 32 bit case,
  
  mostly because the C code ends up significantly faster (around
  
  1.6x faster, with GCC 5.4) when built for aarch64.
  Examples of runtimes vs C on a Cortex A57 (for a slightly older version
  
  of the patch) :
  
                                  A57 gcc-5.3   neon
  
  vp9_inv_adst_adst_4x4_add_neon :       152.2   60.0
  
  vp9_inv_adst_adst_8x8_add_neon :       948.2  288.0
  
  vp9_inv_adst_adst_16x16_add_neon :    4830.4 1380.5
  
  vp9_inv_dct_dct_4x4_add_neon :         153.0   58.6
  
  vp9_inv_dct_dct_8x8_add_neon :         789.2  180.2
  
  vp9_inv_dct_dct_16x16_add_neon :      3639.6  917.1
  
  vp9_inv_dct_dct_32x32_add_neon :     20462.1 4985.0
  
  vp9_inv_wht_wht_4x4_add_neon :          91.0   49.8
  The asm is around factor 3-4 faster than C on the cortex-a57 and the asm
  
  is around 30-50% faster on the a57 compared to the a53.
  This is an adapted cherry-pick from libav commit
  
  3c9546dfafcdfe8e7860aff9ebbf609318220f29.
  Signed-off-by : Ronald S. Bultje <rsbultje@gmail.com>
  

  • [DH] libavcodec/aarch64/Makefile
  • [DH] libavcodec/aarch64/vp9dsp_init_aarch64.c
  • [DH] libavcodec/aarch64/vp9itxfm_neon.S

• How to calculate the start time of mp4 video ?

  27 mai 2022, par Neil Galiaskarov

  I am studying mp4 video structure. I have an issue with reading the start time value for the following mp4 video

  


  I have read this answer
mp4 video starts at different time on Quicktime/AVplayer vs Chrome/Firefox

  


  and it says that Edit atom can modify the start time.

  


  Using ffprobe I have the following output :

  


      "start_time": "0.033333",
    "duration_ts": 327,
    "duration": "10.900000",
    "bit_rate": "9420949",


  


  Using mp4dumper I have the following atoms structure which proves missing Edit atom file :

  


  ftyp (24 @ 0)
free (8 @ 24)
moov (7034 @ 32)
  mvhd (108 @ 40)
  trak (2883 @ 148)
      tkhd (92 @ 156)
      mdia (2783 @ 248)
          mdhd (32 @ 256)
          hdlr (52 @ 288)
          minf (2691 @ 340)
              smhd (16 @ 348)
              dinf (36 @ 364)
                  dref (28 @ 372)
                      url  (12 @ 388)
              stbl (2631 @ 400)
                  stsd (91 @ 408)
                      mp4a (75 @ 424)
                  stts (24 @ 499)
                  stsc (304 @ 523)
                  stsz (2056 @ 827)
                  stco (148 @ 2883)
  trak (4035 @ 3031)
      tkhd (92 @ 3039)
      mdia (3935 @ 3131)
          mdhd (32 @ 3139)
          hdlr (52 @ 3171)
          minf (3843 @ 3223)
              vmhd (20 @ 3231)
              dinf (36 @ 3251)
                  dref (28 @ 3259)
                      url  (12 @ 3275)
              stbl (3779 @ 3287)
                  stsd (163 @ 3295)
                      avc1 (147 @ 3311)
                  stts (24 @ 3458)
                  ctts (1960 @ 3482)
                  stsc (40 @ 5442)
                  stsz (1328 @ 5482)
                  stco (148 @ 6810)
                  stss (108 @ 6958)
mdat (13096745 @ 7066)


  


  How ffprobe calculates 0.033333 start time value ?