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• avcodec/sanm : recognize common FOBJ sizes

  29 avril, par Manuel Lauss

  avcodec/sanm : recognize common FOBJ sizes
  Change the size detection a bit to recognize common video sizes,
  
  as the FOBJ codecs>=37 cannot always be trusted, since they can
  
  be embedded in a larger frame.
  Signed-off-by : Manuel Lauss <manuel.lauss@gmail.com>
  

  • [DH] libavcodec/sanm.c

• Revision d1cff2deb1 : Code cleanup in bitstream code. Lower case variable names, less code. Change-I

  9 avril 2013, par Dmitry Kovalev

  Changed Paths : Modify /vp9/encoder/vp9_bitstream.c Code cleanup in bitstream code. Lower case variable names, less code. Change-Id : I1abc8f592ad2343ab5c76fe2d16262741a4a894a

• Extracted .wav file from .mp4 video with ffmpeg only has half of the duration

  16 mars 2021, par TheSprinter

  I've been using ffmpeg to extract .wav files from .mp4 videos to then generate waveforms and spectrograms for it, but I stumbled upon a file for which ffmpeg does not generate the full audio file. The video duration is 25:25 (25 minutes and 25 seconds), but the .wav file is 12:28 (12 minutes and 28 seconds).

  


  This is what I've been doing :

  


  C:\Users\<user>> ffmpeg -i video.mp4 -ab 160k -ac 1 -ar 44100 -vn audio.wav&#xA;</user>

  


  I tried with -ac 2 only to see if I get something different, but the result is the same. In fact, I can't generate the plots I need with a stereo audio file.

  


  This is what I get in the terminal when I run the command :

  


  C:\Users\<user>>ffmpeg -i video.mp4 -ab 160k -ac 1 -ar 44100 -vn audio.wav&#xA;ffmpeg version 4.3 Copyright (c) 2000-2020 the FFmpeg developers&#xA;  built with gcc 9.3.1 (GCC) 20200621&#xA;  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --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-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libgsm --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf&#xA;  libavutil      56. 51.100 / 56. 51.100&#xA;  libavcodec     58. 91.100 / 58. 91.100&#xA;  libavformat    58. 45.100 / 58. 45.100&#xA;  libavdevice    58. 10.100 / 58. 10.100&#xA;  libavfilter     7. 85.100 /  7. 85.100&#xA;  libswscale      5.  7.100 /  5.  7.100&#xA;  libswresample   3.  7.100 /  3.  7.100&#xA;  libpostproc    55.  7.100 / 55.  7.100&#xA;Input #0, mov,mp4,m4a,3gp,3g2,mj2, from &#x27;audio.mp4&#x27;:&#xA;  Metadata:&#xA;    major_brand     : mp42&#xA;    minor_version   : 0&#xA;    compatible_brands: mp42mp41&#xA;    creation_time   : 2021-03-09T05:00:00.000000Z&#xA;  Duration: 00:25:25.29, start: 0.000000, bitrate: 2308 kb/s&#xA;    Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1280x720, 4410 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)&#xA;    Metadata:&#xA;      creation_time   : 2021-03-09T05:00:00.000000Z&#xA;      handler_name    : ?Mainconcept Video Media Handler&#xA;      encoder         : AVC Coding&#xA;    Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 253 kb/s (default)&#xA;    Metadata:&#xA;      creation_time   : 2021-03-09T05:00:00.000000Z&#xA;      handler_name    : #Mainconcept MP4 Sound Media Handler&#xA;Stream mapping:&#xA;  Stream #0:1 -> #0:0 (aac (native) -> pcm_s16le (native))&#xA;Press [q] to stop, [?] for help&#xA;Output #0, wav, to &#x27;audio.wav&#x27;:&#xA;  Metadata:&#xA;    major_brand     : mp42&#xA;    minor_version   : 0&#xA;    compatible_brands: mp42mp41&#xA;    ISFT            : Lavf58.45.100&#xA;    Stream #0:0(eng): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, mono, s16, 705 kb/s (default)&#xA;    Metadata:&#xA;      creation_time   : 2021-03-09T05:00:00.000000Z&#xA;      handler_name    : #Mainconcept MP4 Sound Media Handler&#xA;      encoder         : Lavc58.91.100 pcm_s16le&#xA;size=   64463kB time=00:12:28.41 bitrate= 705.6kbits/s speed= 156x&#xA;video:0kB audio:64463kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000118%&#xA;</user>

  


  If this information on the video is not enough to troubleshoot, the video says the following (when it starts, for the first few seconds) :

  


  
EP TRT (23.976): 01:24:53:18
EP TRT (29.976): 01:24:55:06

AUDIO LAYOUT

Channel 1: Left Front (L)
Channel 2: Right Front (R)
Channel 3: Center (C)
Channel 4: Low Frequency/Effects (LFE)
Channel 5: Left Surround (Ls)
Channel 6: Right Surround (Rs)
Channel 7: Mono Mix (L)
Channel 8: Mono Mix (R)


  


  This is for TV, that's why you see that longer duration. I don't know if all this is relevant, actually.

  


  Some additional info

  


  Something curious is that I'm doing this for manual tests, but I'm actually creating an app with python and, for that, I'm using python-ffmpeg module, and I with that I'm getting the correct .wav file (with the correct duration). The python lines for this are the following :

  


  (
                        ffmpeg
                        .input(
                            
                        )
                        .output(
                            ,
                            audio_bitrate=316000,
                            ac=1,
                            ar=48000
                        )
                        .run()
)