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• After transcoding using ffmpeg, I found audio bitrate is not the value I expected

  16 mai 2017, par penny

  I used ffmpeg to transcode some files into new format and with certain parameters. After transcoding, I found some output file’s metadata is not what I expected, the output value is not the same with I set in the cmd line.

  Before transcoding I check the media info of the inputfile :

  ffmpeg -i dz2015082000010.mpg

  ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 4.8.3 (GCC) 20140911 (Red Hat 4.8.3-9)
  configuration : —enable-static —enable-memalign-hack —enable-libx264
  —enable-gpl —enable-pthreads —enable-version3 —enable-avisynth —enable-bzlib —enable-iconv —enable-zlib —enable-nonfree —extra-cflags=-I/usr/local/include/ —extra-ldflags=-L/usr/local/lib —enable-debug=3 —disable-optimizations —enable-nonfree —enable-libmp3lame libavutil 55. 34.101 / 55. 34.101 libavcodec 57. 64.101 / 57. 64.101 libavformat 57. 56.101 /
  57. 56.101 libavdevice 57. 1.100 / 57. 1.100 libavfilter 6. 65.100 / 6. 65.100 libswscale 4. 2.100 / 4. 2.100 libswresample 2. 3.100 / 2. 3.100 libpostproc 54. 1.100 /
  54. 1.100 Input #0, mpeg, from ’dz2015082000010.mpg’ : Duration : 00:01:49.30, start : 0.685389, bitrate : 15723 kb/s
  Stream #0:0[0x1e0] : Video : mpeg2video (Main), yuv420p(tv, top first), 1920x1080 [SAR 1:1 DAR 16:9], 15000 kb/s, 25 fps, 25 tbr,
  90k tbn, 50 tbc
  Stream #0:1[0x1c0] : Audio : mp2, 48000 Hz, stereo, s16p, 384 kb/s At least one output file must be specified

  Next, transcoding with the cmd line :

  ffmpeg -i dz2015082000010.mpg -vcodec libx264 -b:v 4000k -s 1920x1080 -r 25 -g 25  -vprofile main -acodec aac -strict -2 -b:a 128k -ac 2 -ar 44100 -y output.ts

  After transcoding, I check the media info of the output file :

  ffmpeg -i output.ts    

  ffmpeg version 3.2.4 Copyright (c) 2000-2017 the FFmpeg developers built with gcc 4.8.3 (GCC) 20140911 (Red Hat
  4.8.3-9) configuration : —enable-static —enable-memalign-hack —enable-libx264 —enable-gpl —enable-pthreads —enable-version3 —enable-avisynth —enable-bzlib —enable-iconv —enable-zlib —enable-nonfree —extra-cflags=-I/usr/local/include/ —extra-ldflags=-L/usr/local/lib —enable-debug=3 —disable-optimizations —enable-nonfree —enable-libmp3lame libavutil 55. 34.101 / 55. 34.101 libavcodec 57. 64.101
  / 57. 64.101 libavformat 57. 56.101 / 57. 56.101
  libavdevice 57. 1.100 / 57. 1.100 libavfilter 6. 65.100
  / 6. 65.100 libswscale 4. 2.100 / 4. 2.100
  libswresample 2. 3.100 / 2. 3.100 libpostproc 54. 1.100
  / 54. 1.100 Input #0, mpegts, from ’full-2.ts’ : Duration :
  00:01:49.30, start : 1.456778, bitrate : 4455 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), 1920x1080 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr,
  90k tbn, 50 tbc
  Stream #0:1[0x101] : Audio : aac (LC) ([15][0][0][0] / 0x000F), 44100 Hz, stereo, fltp, 4 kb/s At least one output file must be
  specified

  I don’t know why the audio bitrate is changed to 4 kb/s after transcoding, I set the value with -b:a 128k before, anybody can help me ? BTW, the output file sounds all right.

• Looping back and forth through frames with ffmpeg

  18 mai 2017, par sebb

  I have a set of ten PNG frames that I’d like to convert to a "boomerang style" mp4 file (i.e go from frame 1 to frame 10, then from 9 to 2). I’d like to find something similar to ImageMagick’s patrol cycle, but can’t figure out how to to it with ffmpeg.

  I thought it would be possible to do this using concat but :

  • I think it’s dirty
  • My command simply does not work :)

  Here’s my command so far :

  -framerate 5 -i "concat:01.png|02.png|03.png|04.png|05.png|06.png|07.png|08.png|09.png|10.png|09.png|08.png|07.png|06.png|05.png|04.png|03.png|02.png" -pix_fmt yuv420p output.mp4

  I get a video file but it just goes from 1 to 10 once.

  Here’s ffmpeg’s saying hello :

  ffmpeg version N-86098-g3fefaea Copyright (c) 2000-2017 the FFmpeg developers
  
  
  
    built with gcc 6.3.0 (GCC)
  
  
  
    configuration: --enable-gpl --enable-version3 --enable-cuda --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --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-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-zlib
  
  
  
    libavutil      55. 63.100 / 55. 63.100
  
  
  
    libavcodec     57. 96.101 / 57. 96.101
  
  
  
    libavformat    57. 72.101 / 57. 72.101
  
  
  
    libavdevice    57.  7.100 / 57.  7.100
  
  
  
    libavfilter     6. 89.101 /  6. 89.101
  
  
  
    libswscale      4.  7.101 /  4.  7.101
  
  
  
    libswresample   2.  8.100 /  2.  8.100
  
  
  
    libpostproc    54.  6.100 / 54.  6.100

  Anyone has an idea ?

  Thanks !

• ffmpeg concatenate image and audio to beginning of file

  18 mai 2017, par swg1cor14

  So I want to try and use the ffmpeg MAP command to do the following :

  Merge audio and jpg
  Concatenate mp4 to end

  Still.jpg
  
  audio.mp3   ->    video.mp4     =    output.mp4

  Right now I have

  /home/admin/ffmpeg/ffmpeg -i still.jpg -i audio.mp3 render1.mp4

  But I want to also go ahead and add on the video.mp4 as well. I tried reading the map function but I’m so confused as to how you know how many streams a file has, etc

  Heres the output of the command....note I have different file names

  Input #0, image2, from 'slide_2.jpg':
  
    Duration: 00:00:00.04, start: 0.000000, bitrate: 8276 kb/s
  
      Stream #0:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1280x720 [SAR 1:1 DAR 16:9], 25 tbr, 25 tbn, 25 tbc
  
  Input #1, mp3, from '/home/admin/web/admin.simplewebevents.com/public_html/cron/steveng1.mp3':
  
    Metadata:
  
      encoder         : Lavf57.56.100
  
    Duration: 00:00:05.78, start: 0.023021, bitrate: 64 kb/s
  
      Stream #1:0: Audio: mp3, 48000 Hz, mono, s16p, 64 kb/s
  
  File 'introFile62.mp4' already exists. Overwrite ? [y/N] y
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mjpeg (native) -> h264 (libx264))
  
    Stream #1:0 -> #0:1 (mp3 (native) -> aac (native))
  
  Press [q] to stop, [?] for help
  
  No pixel format specified, yuvj420p for H.264 encoding chosen.
  
  Use -pix_fmt yuv420p for compatibility with outdated media players.
  
  [libx264 @ 0x3589a00] using SAR=1/1
  
  [libx264 @ 0x3589a00] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
  [libx264 @ 0x3589a00] profile High, level 3.1
  
  [libx264 @ 0x3589a00] 264 - core 148 - H.264/MPEG-4 AVC codec - Copyleft 2003-2017 - 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=1 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 'introFile62.mp4':
  
    Metadata:
  
      encoder         : Lavf57.72.101
  
      Stream #0:0: Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuvj420p(pc, progressive), 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 25 fps, 12800 tbn, 25 tbc
  
      Metadata:
  
        encoder         : Lavc57.96.101 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
  
      Stream #0:1: Audio: aac (LC) ([64][0][0][0] / 0x0040), 48000 Hz, mono, fltp, 69 kb/s
  
      Metadata:
  
        encoder         : Lavc57.96.101 aac
  
  frame=    1 fps=0.2 q=28.0 Lsize=      70kB time=00:00:05.76 bitrate=  99.2kbits/s speed=1.27x    
  
  video:18kB audio:49kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 3.483214%
  
  [libx264 @ 0x3589a00] frame I:1     Avg QP:25.71  size: 18268
  
  [libx264 @ 0x3589a00] mb I  I16..4: 25.6% 63.4% 10.9%
  
  [libx264 @ 0x3589a00] 8x8 transform intra:63.4%
  
  [libx264 @ 0x3589a00] coded y,uvDC,uvAC intra: 14.3% 18.5% 8.9%
  
  [libx264 @ 0x3589a00] i16 v,h,dc,p: 81%  9% 10%  1%
  
  [libx264 @ 0x3589a00] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 50% 12% 33%  1%  1%  1%  0%  1%  1%
  
  [libx264 @ 0x3589a00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 46% 21% 13%  3%  4%  5%  2%  4%  2%
  
  [libx264 @ 0x3589a00] i8c dc,h,v,p: 76%  8% 15%  1%
  
  [libx264 @ 0x3589a00] kb/s:3653.60
  
  [aac @ 0x358aea0] Qavg: 118.057