ffmpeg altera a taxa de bits de áudio quando transcodifica de MKV para FLV

Question

ffmpeg altera a taxa de bits de áudio quando transcodifica de MKV para FLV

#1 resposta do (2 votos)

1

Eu tenho um arquivo - sample.mkv

=========================================================
               File: sample.mkv
              Width: 854 pixels
             Height: 480 pixels
       Aspect ratio: 1.77:1
             Frames: 0
           Duration: 00:00:33 hours/mins/secs
          Framerate: 25.000 frames per second
       Video format: H264
      Video bitrate: 0 bits per second
---------------------------
Audio track 1 (Stream 0.1, AID 0):
---------------------------
              Codec: pcm_s16le
            Bitrate: 4233000 bits per second
      Sampling rate: 44100 Hz
=========================================================

Eu quero recodificá-lo no contêiner FLV via ffmpeg:

$ ffmpeg -i sample.mkv -b:a 4233k -c:v h264 -c:a pcm_s16le sample.flv

mas recebi:

=========================================================
               File: sample.flv
              Width: 854 pixels
             Height: 480 pixels
       Aspect ratio: 1.77:1
             Frames: 0
           Duration: 00:00:33 hours/mins/secs
          Framerate: 25.000 frames per second
       Video format: H264
      Video bitrate: 0 bits per second
---------------------------
Audio track 1 (Stream 0.1, AID 0):
---------------------------
              Codec: pcm_s16le
            Bitrate: 1411000 bits per second
      Sampling rate: 44100 Hz
=========================================================

Por que a taxa de bits vai para 4233000 - > 1411000?
A este respeito, o som acaba muito mal: (

ATUALIZAÇÃO log completo

ffmpeg -i sample.mkv -b:a 4233k -c:v h264 -c:a pcm_s16le sample.flv
ffmpeg version 2.6.2 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --prefix=/opt/ffmpeg --libdir=/opt/ffmpeg/lib/ --enable-shared --enable-avresample --disable-stripping --enable-gpl --enable-version3 --enable-nonfree --enable-runtime-cpudetect --build-suffix=.ffmpeg --enable-postproc --enable-x11grab --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libdc1394 --enable-libfaac --enable-libfdk_aac --enable-libflite --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libvo-aacenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-openal --enable-opengl --enable-pthreads --enable-vaapi --enable-vdpau --enable-zlib --enable-debug=3
  libavutil      54. 20.100 / 54. 20.100
  libavcodec     56. 26.100 / 56. 26.100
  libavformat    56. 25.101 / 56. 25.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 11.102 /  5. 11.102
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Guessed Channel Layout for  Input Stream #0.1 : 5.1
Input #0, matroska,webm, from 'sample.mkv':
  Metadata:
    MINOR_VERSION   : 512
    COMPATIBLE_BRANDS: qt  
    MAJOR_BRAND     : qt  
    ENCODER         : Lavf56.25.101
  Duration: 00:00:33.08, start: 0.080000, bitrate: 4691 kb/s
    Stream #0:0(eng): Video: h264 (High), yuv420p, 854x480 [SAR 1:1 DAR 427:240], 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
    Metadata:
      LANGUAGE        : eng
      HANDLER_NAME    : DataHandler
      ENCODER         : Lavc56.26.100 libx264
    Stream #0:1(eng): Audio: pcm_s16le, 44100 Hz, 6 channels, s16, 4233 kb/s (default)
    Metadata:
      LANGUAGE        : eng
      HANDLER_NAME    : DataHandler
      ENCODER         : Lavc56.26.100 pcm_s16le
[libx264 @ 0x914de0] using SAR=1/1
[libx264 @ 0x914de0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x914de0] profile High, level 3.0
[libx264 @ 0x914de0] 264 - core 142 r2389 956c8d8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - 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=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, flv, to 'sample.flv':
  Metadata:
    MINOR_VERSION   : 512
    COMPATIBLE_BRANDS: qt  
    MAJOR_BRAND     : qt  
    encoder         : Lavf56.25.101
    Stream #0:0(eng): Video: h264 (libx264) ([7][0][0][0] / 0x0007), yuv420p, 854x480 [SAR 1:1 DAR 427:240], q=-1--1, 25 fps, 1k tbn, 25 tbc (default)
    Metadata:
      LANGUAGE        : eng
      HANDLER_NAME    : DataHandler
      encoder         : Lavc56.26.100 libx264
    Stream #0:1(eng): Audio: pcm_s16le ([3][0][0][0] / 0x0003), 44100 Hz, 5.1, s16, 4233 kb/s (default)
    Metadata:
      LANGUAGE        : eng
      HANDLER_NAME    : DataHandler
      encoder         : Lavc56.26.100 pcm_s16le
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (pcm_s16le (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
frame=  812 fps= 93 q=-1.0 Lsize=   18938kB time=00:00:33.00 bitrate=4700.7kbits/s    
video:1841kB audio:17056kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.214361%
[libx264 @ 0x914de0] frame I:23    Avg QP:16.97  size: 20207
[libx264 @ 0x914de0] frame P:294   Avg QP:20.61  size:  3904
[libx264 @ 0x914de0] frame B:495   Avg QP:23.24  size:   550
[libx264 @ 0x914de0] consecutive B-frames: 15.0%  7.9%  9.6% 67.5%
[libx264 @ 0x914de0] mb I  I16..4: 34.6% 45.1% 20.3%
[libx264 @ 0x914de0] mb P  I16..4:  3.5% 12.4%  0.8%  P16..4: 19.1%  5.7%  2.4%  0.0%  0.0%    skip:56.0%
[libx264 @ 0x914de0] mb B  I16..4:  0.4%  0.4%  0.1%  B16..8: 12.5%  1.0%  0.1%  direct: 0.5%  skip:85.1%  L0:43.1% L1:50.9% BI: 5.9%
[libx264 @ 0x914de0] 8x8 transform intra:64.0% inter:75.7%
[libx264 @ 0x914de0] coded y,uvDC,uvAC intra: 33.0% 43.7% 13.4% inter: 4.1% 6.8% 1.0%
[libx264 @ 0x914de0] i16 v,h,dc,p: 53% 22%  9% 16%
[libx264 @ 0x914de0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 27% 21% 27%  3%  5%  4%  5%  4%  4%
[libx264 @ 0x914de0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 28% 20% 12%  5%  7%  9%  6%  8%  5%
[libx264 @ 0x914de0] i8c dc,h,v,p: 62% 20% 14%  5%
[libx264 @ 0x914de0] Weighted P-Frames: Y:32.0% UV:30.6%
[libx264 @ 0x914de0] ref P L0: 72.5% 16.1%  8.0%  3.3%  0.1%
[libx264 @ 0x914de0] ref B L0: 86.4% 11.6%  2.0%
[libx264 @ 0x914de0] ref B L1: 95.1%  4.9%
[libx264 @ 0x914de0] kb/s:464.26

UPDATE 2:

ffmpeg -i sample.mkv -ac 6 -c copy sample.flv
ffmpeg version 2.6.2 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: --prefix=/opt/ffmpeg --libdir=/opt/ffmpeg/lib/ --enable-shared --enable-avresample --disable-stripping --enable-gpl --enable-version3 --enable-nonfree --enable-runtime-cpudetect --build-suffix=.ffmpeg --enable-postproc --enable-x11grab --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libdc1394 --enable-libfaac --enable-libfdk_aac --enable-libflite --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libvo-aacenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-openal --enable-opengl --enable-pthreads --enable-vaapi --enable-vdpau --enable-zlib --enable-debug=3
  libavutil      54. 20.100 / 54. 20.100
  libavcodec     56. 26.100 / 56. 26.100
  libavformat    56. 25.101 / 56. 25.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 11.102 /  5. 11.102
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100
  libpostproc    53.  3.100 / 53.  3.100
Guessed Channel Layout for  Input Stream #0.1 : 5.1
Input #0, matroska,webm, from 'sample.mkv':
  Metadata:
    MINOR_VERSION   : 512
    COMPATIBLE_BRANDS: qt  
    MAJOR_BRAND     : qt  
    ENCODER         : Lavf56.25.101
  Duration: 00:00:33.08, start: 0.080000, bitrate: 4691 kb/s
    Stream #0:0(eng): Video: h264 (High), yuv420p, 854x480 [SAR 1:1 DAR 427:240], 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
    Metadata:
      LANGUAGE        : eng
      HANDLER_NAME    : DataHandler
      ENCODER         : Lavc56.26.100 libx264
    Stream #0:1(eng): Audio: pcm_s16le, 44100 Hz, 6 channels, s16, 4233 kb/s (default)
    Metadata:
      LANGUAGE        : eng
      HANDLER_NAME    : DataHandler
      ENCODER         : Lavc56.26.100 pcm_s16le
Output #0, flv, to 'sample.flv':
  Metadata:
    MINOR_VERSION   : 512
    COMPATIBLE_BRANDS: qt  
    MAJOR_BRAND     : qt  
    encoder         : Lavf56.25.101
    Stream #0:0(eng): Video: h264 ([7][0][0][0] / 0x0007), yuv420p, 854x480 [SAR 1:1 DAR 427:240], q=2-31, 25 fps, 25 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      LANGUAGE        : eng
      HANDLER_NAME    : DataHandler
      ENCODER         : Lavc56.26.100 libx264
    Stream #0:1(eng): Audio: pcm_s16le ([3][0][0][0] / 0x0003), 44100 Hz, 5.1, 4233 kb/s (default)
    Metadata:
      LANGUAGE        : eng
      HANDLER_NAME    : DataHandler
      ENCODER         : Lavc56.26.100 pcm_s16le
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame=  812 fps=0.0 q=-1.0 Lsize=   18968kB time=00:00:33.00 bitrate=4708.2kbits/s    
video:1872kB audio:17056kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.214011%

video ffmpeg video-conversion audio

por Dima00782 03.05.2015 / 12:23

1 resposta

Tags video ffmpeg video-conversion audio

Não é possível adicionar um provedor de pesquisa no IE 11 no Windows 7 x64 Pare o Windows 8.1 atualizando automaticamente o driver Intel HD Graphics 4000

score 2 · Accepted Answer

Até onde eu sei, o formato FLV não suporta oficialmente áudio não-comprimido no formato PCM (veja a especificação ). No entanto, você ainda pode multiplexar áudio PCM em FLV com ffmpeg. Parece haver um bug ou incompatibilidade com ffplay não reproduzir o áudio corretamente, mas funciona para mim no VLC:

ffmpeg -i sample.mkv -c copy sample.flv

Se você deseja ser mais compatível com outros players, convém restringir o áudio a dois canais. Para fazer isso:

ffmpeg -i sample.mkv -c:v copy -c:a pcm_s16le -ac 2 sample.flv

Isso reduzirá o número de canais de áudio, mas eles não perderão qualidade. A taxa de bits será menor, mas menos canais.

Suas outras opções são áudio AAC ou áudio MP3:

ffmpeg -i sample.mkv -c:v copy -c:a aac -strict experimental -b:a 128k sample.flv
ffmpeg -i sample.mkv -c:v copy -c:a libmp3lame sample.flv

Isso converterá automaticamente o áudio multicanal para estéreo.

Observe que, se estiver usando MP3 em FLV, você estará restrito às seguintes taxas de amostragem de áudio: 44100, 22050, 11025. Isso pode ser definido com a opção -ar ou aresample filter.