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• On ALAC’s Open Sourcing

  1er novembre 2011, par Multimedia Mike — Codec Technology

  Apple open sourced their lossless audio codec last week. Pretty awesome ! I have a theory that, given enough time, absolutely every codec will be open source in one way or another.

  I know I shouldn’t bother reading internet conversation around any news related to multimedia technology. And if I do read it, I shouldn’t waste any effort getting annoyed about them. But here are some general corrections :

  • ALAC is not in the same league as — nor is it a suitable replacement for — MP3/AAC/Vorbis or any other commonly used perceptual audio codec. It’s not a matter of better or worse ; they’re just different families of codecs designed for different purposes.
  • Apple open sourced ALAC, not AAC– easy mistake, though there’s nothing to ‘open source’ about AAC (though people can, and will, argue about its absolute ‘open-ness’).
  • There’s not much technical room to argue between ALAC and FLAC, the leading open source lossless audio compressor. Both perform similarly in terms of codec speeds (screamingly fast) and compression efficiency (results vary slightly depending on source material).
  • Perhaps the most frustrating facet is the blithe ignorance about ALAC’s current open source status. While this event simply added an official “open source” status to the codec, ALAC has effectively been open source for a very long time. According to my notes, the ALAC decoding algorithm was reverse engineered in 2005 and added into FFmpeg in March of the same year. Then in 2008, Google — through their Summer of Code program — sponsored an open source ALAC encoder.

  From the multimedia-savvy who are versed in these concepts, the conversation revolves around which would win in a fight, ALAC or FLAC ? And who between Apple and FFmpeg/Libav has a faster ALAC decoder ? The faster and more efficient ALAC encoder ? I contend that these issues don’t really matter. If you have any experience working with lossless audio encoders, you know that they tend to be ridiculously fast to both encode and decode and that many different lossless codecs compress at roughly the same ratios.

  As for which encoder is the fastest : use whatever encoder is handiest and most familiar, either iTunes or FFmpeg/Libav.

  As for whether to use FLAC or ALAC — if you’ve already been using one or the other for years, keep on using it. Support isn’t going to vanish. If you’re deciding which to use for a new project, again, perhaps choose based on software you’re already familiar with. Also, consider hardware support– ALAC enjoys iPod support, FLAC is probably better supported in a variety of non-iPod devices, though that may change going forward due to this open sourcing event.

  For my part, I’m just ecstatic that the question of moral superiority based on open source status has been removed from the equation.

  Code-wise, I’m interested in studying the official ALAC code to see if it has any corner-case modes that the existing open source decoders don’t yet account for. The source makes mention of multichannel (i.e., greater than stereo) configurations, but I don’t know if that’s in FFmpeg/Libav.

• Convert a video with content type video/quicktime to video/mp4 using ffmpeg

  25 juin 2021, par schub

  I have a strange problem. I start with a video file recored with an iPhone. The output is video.mov. I convert this to mp4 using ffmpeg :

  


  ffmpeg -i video.mov -vcodec h264 -acodec aac video.mp4

  


  If I use a tool like exiftool to show the metadata the output for content-type is video/mp4 all seems to be correct. But my backend, which receives the video, uses a library called Apache Tika to extract the content type and the result here is : video/quicktime.

  


  Scala code to retrieve the content type from the file :

  


  // byteArray: Array[Byte]

val tika        = new TikaConfig()
val metadata    = new Metadata()
val contentType = tika.getDetector.detect(TikaInputStream.get(byteArray), metadata)


  


  BTW : If I use a video editing program (DaVinci Resolve in my case) I can load the video, adjust settings and explicitly set the codec to mp4, export the video and then the resulting file works and Apache Tika extract the desired content-type. This is a workaround, but it does not scale and I like to automate this process via ffmpeg.

  


  I'm stuck here. Can anyone give me a hint what I can do ?

  


  Versions :

  


  tika : 1.22
  
ffmpeg : 4.4

  


  ffmpeg log :

  


  $ffmpeg -i video.mov -vcodec h264 -acodec aac video.mp4
ffmpeg version 4.4 Copyright (c) 2000-2021 the FFmpeg developers
  built with Apple clang version 12.0.0 (clang-1200.0.32.29)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.4_2 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-avresample --enable-videotoolbox
  libavutil      56. 70.100 / 56. 70.100
  libavcodec     58.134.100 / 58.134.100
  libavformat    58. 76.100 / 58. 76.100
  libavdevice    58. 13.100 / 58. 13.100
  libavfilter     7.110.100 /  7.110.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  9.100 /  5.  9.100
  libswresample   3.  9.100 /  3.  9.100
  libpostproc    55.  9.100 / 55.  9.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    creation_time   : 2021-06-24T11:19:37.000000Z
    com.apple.quicktime.location.accuracy.horizontal: 65.000000
    com.apple.quicktime.location.ISO6709: +52.5554+013.3772+042.268/
    com.apple.quicktime.make: Apple
    com.apple.quicktime.model: iPhone 8
    com.apple.quicktime.software: 14.4.2
    com.apple.quicktime.creationdate: 2021-06-24T13:19:36+0200
  Duration: 00:00:09.83, start: 0.000000, bitrate: 7954 kb/s
  Stream #0:0(und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, bt709), 1920x1080, 7810 kb/s, 30.01 fps, 30 tbr, 600 tbn, 600 tbc (default)
    Metadata:
      rotate          : 90
      creation_time   : 2021-06-24T11:19:37.000000Z
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
      encoder         : HEVC
    Side data:
      displaymatrix: rotation of -90.00 degrees
  Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 96 kb/s (default)
    Metadata:
      creation_time   : 2021-06-24T11:19:37.000000Z
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
  Stream #0:2(und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
    Metadata:
      creation_time   : 2021-06-24T11:19:37.000000Z
      handler_name    : Core Media Metadata
  Stream #0:3(und): Data: none (mebx / 0x7862656D), 0 kb/s (default)
    Metadata:
      creation_time   : 2021-06-24T11:19:37.000000Z
      handler_name    : Core Media Metadata
  Stream #0:4(und): Data: none (mebx / 0x7862656D), 34 kb/s (default)
    Metadata:
      creation_time   : 2021-06-24T11:19:37.000000Z
      handler_name    : Core Media Metadata
Stream mapping:
  Stream #0:0 -> #0:0 (hevc (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0x7fbe08009400] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0x7fbe08009400] profile High, level 4.0, 4:2:0, 8-bit
[libx264 @ 0x7fbe08009400] 264 - core 163 r3060 5db6aa6 - H.264/MPEG-4 AVC codec - Copyleft 2003-2021 - 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=12 lookahead_threads=2 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 'video.mp4':
  Metadata:
    major_brand     : qt
    minor_version   : 0
    compatible_brands: qt
    com.apple.quicktime.creationdate: 2021-06-24T13:19:36+0200
    com.apple.quicktime.location.accuracy.horizontal: 65.000000
    com.apple.quicktime.location.ISO6709: +52.5554+013.3772+042.268/
    com.apple.quicktime.make: Apple
    com.apple.quicktime.model: iPhone 8
    com.apple.quicktime.software: 14.4.2
    encoder         : Lavf58.76.100
  Stream #0:0(und): Video: h264 (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1080x1920, q=2-31, 30 fps, 15360 tbn (default)
    Metadata:
      encoder         : Lavc58.134.100 libx264
      creation_time   : 2021-06-24T11:19:37.000000Z
      handler_name    : Core Media Video
      vendor_id       : [0][0][0][0]
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
      displaymatrix: rotation of -0.00 degrees
  Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 69 kb/s (default)
    Metadata:
      creation_time   : 2021-06-24T11:19:37.000000Z
      handler_name    : Core Media Audio
      vendor_id       : [0][0][0][0]
      encoder         : Lavc58.134.100 aac
frame=  295 fps= 18 q=-1.0 Lsize=    9980kB time=00:00:09.82 bitrate=8323.6kbits/s speed=0.614x
video:9884kB audio:85kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.103401%
[libx264 @ 0x7fbe08009400] frame I:6     Avg QP:21.84  size: 50301
[libx264 @ 0x7fbe08009400] frame P:217   Avg QP:24.23  size: 35435
[libx264 @ 0x7fbe08009400] frame B:72    Avg QP:24.97  size: 29582
[libx264 @ 0x7fbe08009400] consecutive B-frames: 66.8%  0.7%  4.1% 28.5%
[libx264 @ 0x7fbe08009400] mb I  I16..4:  6.7% 88.9%  4.4%
[libx264 @ 0x7fbe08009400] mb P  I16..4:  4.2% 32.9%  0.5%  P16..4: 49.6%  5.0%  2.3%  0.0%  0.0%    skip: 5.5%
[libx264 @ 0x7fbe08009400] mb B  I16..4:  0.9%  6.9%  0.0%  B16..8: 51.8%  7.7%  0.8%  direct:12.2%  skip:19.6%  L0:50.1% L1:46.9% BI: 3.0%
[libx264 @ 0x7fbe08009400] 8x8 transform intra:87.7% inter:88.8%
[libx264 @ 0x7fbe08009400] coded y,uvDC,uvAC intra: 59.2% 41.2% 0.9% inter: 38.3% 57.3% 0.0%
[libx264 @ 0x7fbe08009400] i16 v,h,dc,p: 15% 23%  8% 53%
[libx264 @ 0x7fbe08009400] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 16% 14% 29%  7%  8%  7%  7%  6%  6%
[libx264 @ 0x7fbe08009400] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 23% 18% 18%  9% 11%  7%  7%  4%  3%
[libx264 @ 0x7fbe08009400] i8c dc,h,v,p: 60% 20% 18%  1%
[libx264 @ 0x7fbe08009400] Weighted P-Frames: Y:3.2% UV:2.3%
[libx264 @ 0x7fbe08009400] ref P L0: 54.2% 10.7% 22.2% 12.5%  0.4%
[libx264 @ 0x7fbe08009400] ref B L0: 75.5% 19.6%  4.9%
[libx264 @ 0x7fbe08009400] ref B L1: 88.7% 11.3%
[libx264 @ 0x7fbe08009400] kb/s:8234.01
[aac @ 0x7fbe0802e000] Qavg: 446.889


  


• How to use the Source Code instead of a specific OS App with a Python Project [closed]

  28 septembre 2021, par Lara Saka

  If I want for example to install ffmpeg to use AudioSegment Library(which convert Audio to text). When you open their website you will see download for windows, apple, linux and a source code I want to use the ffmpeg in the Project regardless of the operating system by using the source code of the ffmpeg !

  


  How Can I do that ?

  


  ffmpeg download web site

  


  Thanks in advance..