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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.

• Encode loopback capture data in mp3 using ffmpeg in VC++

  16 octobre 2013, par NetCoder89

  I'm trying to work on loopback capture(What you hear) and record this file in mp3/aac format using VC++.
   >I can capture audio and can create a .wav file i.e. not compressed but I want a compressed file so I'm encoding this through ffmpeg to write an mp3 file not a .wav.

  However I'm not getting any way to do it directly ?
  I referred this for loopback capture.

  Please share your experience and opinions.

  Thanks !

• HTML5 Video Chrome - ffmpeg - mp4 working in all but Chrome

  16 octobre 2014, par IIIOXIII

  I have successfully encoded a file to .mp4 using ffmpeg which will play in all tested devices (Safari on PC, IE on PC, Android Browser, Andriod Video Player, and Safari iPad), except for Chrome.

  As a work-around, I had planned to simply list the .ogg source prior to the .mp4 source so that chrome would play the .ogg source without even seeing the .mp4 source, however, I ran into the issue mentioned here.

  Basically, I am after the proper ffmpeg command which will encode an .mp4 video to standards which will play in Chrome - of course without losing playback functionality on any of the other previously mentioned platforms.

  I have tried several combinations, such as :

  ffmpeg -i [filename].wmv -vprofile baseline -level 30 -vf scale=640:-1 -movflags faststart [filename].mp4

  etc. but have not yet found the winning one.

  EDIT : I tried :

  ffmpeg_new -i [filename].wmv -strict experimental –acodec libvo_aacenc -ac 2 -ab 160k -vcodec libx264 -vf scale=640:-1 -pix_fmt yuv420p -preset slow -profile:v baseline -level 30 -maxrate 10000000 -bufsize 10000000 -b 1200k -f mp4 -threads 0 [filename].mp4

  And here is the ffmpeg output :

  ffmpeg version N-54207-ge59fb3f Copyright (c) 2000-2013 the FFmpeg developers built on Jun 25 2013 21:55:00 with gcc 4.7.3 (GCC)
  
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetyp
  
  e --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --ena
  
  ble-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-l
  
  ibopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libsp
  
  eex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-
  
  amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --
  
  enable-libxvid --enable-zlib
  
    libavutil      52. 37.101 / 52. 37.101
  
    libavcodec     55. 17.100 / 55. 17.100
  
    libavformat    55. 10.100 / 55. 10.100
  
    libavdevice    55.  2.100 / 55.  2.100
  
    libavfilter     3. 77.101 /  3. 77.101
  
    libswscale      2.  3.100 /  2.  3.100
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  3.100 / 52.  3.100
  
  [asf @ 000000000254f9e0] Stream #0: not enough frames to estimate rate; consider
  
   increasing probesize
  
  Guessed Channel Layout for  Input Stream #0.0 : stereo
  
  Input #0, asf, from 'C:\vidtests\Wildlife.wmv':
  
    Metadata:
  
      SfOriginalFPS   : 299700
  
      WMFSDKVersion   : 11.0.6001.7000
  
      WMFSDKNeeded    : 0.0.0.0000
  
      comment         : Footage: Small World Productions, Inc; Tourism New Zealand
  
   | Producer: Gary F. Spradling | Music: Steve Ball
  
      title           : Wildlife in HD
  
      copyright       : ┬⌐ 2008 Microsoft Corporation
  
      IsVBR           : 0
  
      DeviceConformanceTemplate: AP@L3
  
    Duration: 00:00:30.09, start: 0.000000, bitrate: 6977 kb/s
  
      Stream #0:0(eng): Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, stereo, fltp
  
  , 192 kb/s
  
      Stream #0:1(eng): Video: vc1 (Advanced) (WVC1 / 0x31435657), yuv420p, 1280x7
  
  20, 5942 kb/s, 29.97 tbr, 1k tbn, 1k tbc
  
  Please use -b:a or -b:v, -b is ambiguous
  
  [libx264 @ 000000000264faa0] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64
  
  
  
  [libx264 @ 000000000264faa0] profile Constrained Baseline, level 3.0
  
  [libx264 @ 000000000264faa0] 264 - core 133 r2334 a3ac64b - H.264/MPEG-4 AVC cod
  
  ec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=0 r
  
  ef=5 deblock=1:0:0 analyse=0x1:0x111 me=umh subme=8 psy=1 psy_rd=1.00:0.00 mixed
  
  _ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pski
  
  p=1 chroma_qp_offset=-2 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 deci
  
  mate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyi
  
  nt=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=50 rc=abr mbtree=1
  
   bitrate=1200 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=10000
  
   vbv_bufsize=10000 nal_hrd=none ip_ratio=1.40 aq=1:1.00
  
  Output #0, mp4, to 'C:\vidtests\Wildlife_SE1.mp4':
  
    Metadata:
  
      SfOriginalFPS   : 299700
  
      WMFSDKVersion   : 11.0.6001.7000
  
      WMFSDKNeeded    : 0.0.0.0000
  
      comment         : Footage: Small World Productions, Inc; Tourism New Zealand
  
   | Producer: Gary F. Spradling | Music: Steve Ball
  
      title           : Wildlife in HD
  
      copyright       : ┬⌐ 2008 Microsoft Corporation
  
      IsVBR           : 0
  
      DeviceConformanceTemplate: AP@L3
  
      encoder         : Lavf55.10.100
  
      Stream #0:0(eng): Video: h264 (libx264) ([33][0][0][0] / 0x0021), yuv420p, 6
  
  40x360, q=-1--1, 1200 kb/s, 30k tbn, 29.97 tbc
  
      Stream #0:1(eng): Audio: aac (libvo_aacenc) ([64][0][0][0] / 0x0040), 44100
  
  Hz, stereo, s16, 160 kb/s
  
  Stream mapping:
  
    Stream #0:1 -> #0:0 (vc1 -> libx264)
  
    Stream #0:0 -> #0:1 (wmav2 -> libvo_aacenc)
  
  Press [q] to stop, [?] for help
  
  frame=   59 fps= 55 q=32.0 size=       0kB time=00:00:00.16 bitrate=   2.3kbits/
  
  frame=   66 fps= 42 q=31.0 size=       0kB time=00:00:00.40 bitrate=   1.0kbits/
  
  frame=   75 fps= 35 q=31.0 size=       0kB time=00:00:00.70 bitrate=   0.5kbits/
  
  frame=   84 fps= 31 q=31.0 size=       0kB time=00:00:01.00 bitrate=   0.4kbits/
  
  frame=   93 fps= 29 q=31.0 size=       0kB time=00:00:01.30 bitrate=   0.3kbits/
  
  frame=  102 fps= 27 q=31.0 size=       0kB time=00:00:01.60 bitrate=   0.2kbits/
  
  frame=  111 fps= 26 q=31.0 size=      38kB time=00:00:01.90 bitrate= 165.1kbits/
  
  Queue input is backward in time
  
  [mp4 @ 000000000264f2c0] Non-monotonous DTS in output stream 0:1; previous: 7616
  
  , current: 7063; changing to 7617. This may result in incorrect timestamps in th
  
  e output file.
  
  frame=  120 fps= 25 q=31.0 size=     107kB time=00:00:02.20 bitrate= 397.7kbits/
  
  frame=  128 fps= 24 q=31.0 size=     161kB time=00:00:02.46 bitrate= 534.1kbits/
  
  frame=  137 fps= 23 q=31.0 size=     194kB time=00:00:02.76 bitrate= 572.6kbits/
  
  frame=  145 fps= 23 q=31.0 size=     219kB time=00:00:03.03 bitrate= 592.1kbits/
  
  frame=  153 fps= 22 q=31.0 size=     273kB time=00:00:03.30 bitrate= 677.8kbits/
  
  frame=  162 fps= 22 q=31.0 size=     317kB time=00:00:03.60 bitrate= 720.8kbits/
  
  frame=  170 fps= 21 q=31.0 size=     366kB time=00:00:03.87 bitrate= 775.2kbits/
  
  frame=  177 fps= 21 q=31.0 size=     451kB time=00:00:04.10 bitrate= 900.2kbits/
  
  frame=  193 fps= 21 q=31.0 size=     602kB time=00:00:04.63 bitrate=1062.7kbits/
  
  frame=  208 fps= 22 q=30.0 size=     755kB time=00:00:05.13 bitrate=1204.2kbits/
  
  frame=  219 fps= 22 q=30.0 size=     769kB time=00:00:05.50 bitrate=1143.6kbits/
  
  frame=  228 fps= 21 q=30.0 size=     790kB time=00:00:05.80 bitrate=1114.5kbits/
  
  frame=  234 fps= 21 q=31.0 size=     806kB time=00:00:06.00 bitrate=1098.7kbits/
  
  frame=  243 fps= 21 q=31.0 size=     806kB time=00:00:06.30 bitrate=1046.4kbits/
  
  frame=  251 fps= 21 q=31.0 size=     831kB time=00:00:06.57 bitrate=1035.6kbits/
  
  frame=  260 fps= 20 q=31.0 size=     860kB time=00:00:06.87 bitrate=1024.6kbits/
  
  frame=  273 fps= 21 q=31.0 size=     934kB time=00:00:07.30 bitrate=1046.7kbits/
  
  frame=  288 fps= 21 q=30.0 size=    1019kB time=00:00:07.80 bitrate=1068.7kbits/
  
  frame=  302 fps= 21 q=30.0 size=    1066kB time=00:00:08.27 bitrate=1055.8kbits/
  
  frame=  314 fps= 21 q=29.0 size=    1146kB time=00:00:08.67 bitrate=1082.1kbits/
  
  frame=  328 fps= 21 q=28.0 size=    1189kB time=00:00:09.14 bitrate=1065.6kbits/
  
  frame=  341 fps= 21 q=28.0 size=    1247kB time=00:00:09.57 bitrate=1066.7kbits/
  
  frame=  352 fps= 22 q=27.0 size=    1274kB time=00:00:09.94 bitrate=1049.3kbits/
  
  frame=  365 fps= 22 q=27.0 size=    1298kB time=00:00:10.37 bitrate=1024.7kbits/
  
  frame=  376 fps= 22 q=27.0 size=    1349kB time=00:00:10.74 bitrate=1028.7kbits/
  
  frame=  388 fps= 22 q=26.0 size=    1378kB time=00:00:11.14 bitrate=1012.9kbits/
  
  frame=  401 fps= 22 q=26.0 size=    1415kB time=00:00:11.57 bitrate=1001.4kbits/
  
  frame=  412 fps= 22 q=26.0 size=    1454kB time=00:00:11.94 bitrate= 996.9kbits/
  
  frame=  421 fps= 22 q=27.0 size=    1489kB time=00:00:12.24 bitrate= 996.2kbits/
  
  frame=  431 fps= 21 q=27.0 size=    1509kB time=00:00:12.57 bitrate= 982.7kbits/
  
  frame=  441 fps= 21 q=28.0 size=    1555kB time=00:00:12.91 bitrate= 986.6kbits/
  
  frame=  450 fps= 21 q=28.0 size=    1599kB time=00:00:13.21 bitrate= 991.7kbits/
  
  frame=  460 fps= 21 q=28.0 size=    1621kB time=00:00:13.54 bitrate= 980.4kbits/
  
  frame=  470 fps= 21 q=28.0 size=    1660kB time=00:00:13.88 bitrate= 979.9kbits/
  
  frame=  480 fps= 21 q=28.0 size=    1734kB time=00:00:14.21 bitrate= 999.2kbits/
  
  frame=  489 fps= 21 q=29.0 size=    1834kB time=00:00:14.51 bitrate=1035.3kbits/
  
  frame=  499 fps= 21 q=29.0 size=    1890kB time=00:00:14.84 bitrate=1042.8kbits/
  
  frame=  508 fps= 21 q=29.0 size=    1962kB time=00:00:15.14 bitrate=1060.8kbits/
  
  frame=  519 fps= 21 q=29.0 size=    2061kB time=00:00:15.51 bitrate=1087.9kbits/
  
  frame=  531 fps= 21 q=29.0 size=    2189kB time=00:00:15.91 bitrate=1126.6kbits/
  
  frame=  540 fps= 21 q=29.0 size=    2329kB time=00:00:16.21 bitrate=1176.4kbits/
  
  frame=  551 fps= 21 q=29.0 size=    2439kB time=00:00:16.58 bitrate=1204.8kbits/
  
  frame=  562 fps= 21 q=29.0 size=    2569kB time=00:00:16.95 bitrate=1241.8kbits/
  
  frame=  575 fps= 21 q=29.0 size=    2688kB time=00:00:17.38 bitrate=1266.9kbits/
  
  frame=  581 fps= 21 q=29.0 size=    2749kB time=00:00:17.58 bitrate=1280.6kbits/
  
  frame=  589 fps= 21 q=29.0 size=    2785kB time=00:00:17.85 bitrate=1278.1kbits/
  
  frame=  595 fps= 21 q=30.0 size=    2808kB time=00:00:18.05 bitrate=1274.5kbits/
  
  frame=  602 fps= 20 q=30.0 size=    2903kB time=00:00:18.28 bitrate=1300.7kbits/
  
  frame=  610 fps= 20 q=31.0 size=    3008kB time=00:00:18.55 bitrate=1328.2kbits/
  
  frame=  616 fps= 20 q=31.0 size=    3128kB time=00:00:18.75 bitrate=1366.6kbits/
  
  frame=  625 fps= 20 q=31.0 size=    3238kB time=00:00:19.05 bitrate=1392.5kbits/
  
  frame=  633 fps= 20 q=31.0 size=    3320kB time=00:00:19.31 bitrate=1407.9kbits/
  
  frame=  642 fps= 20 q=31.0 size=    3397kB time=00:00:19.61 bitrate=1418.4kbits/
  
  frame=  652 fps= 20 q=31.0 size=    3437kB time=00:00:19.95 bitrate=1411.1kbits/
  
  frame=  661 fps= 20 q=31.0 size=    3511kB time=00:00:20.25 bitrate=1420.3kbits/
  
  frame=  669 fps= 20 q=31.0 size=    3578kB time=00:00:20.52 bitrate=1428.2kbits/
  
  frame=  679 fps= 20 q=31.0 size=    3606kB time=00:00:20.85 bitrate=1416.6kbits/
  
  frame=  691 fps= 20 q=32.0 size=    3670kB time=00:00:21.25 bitrate=1414.5kbits/
  
  frame=  701 fps= 20 q=32.0 size=    3798kB time=00:00:21.58 bitrate=1441.2kbits/
  
  frame=  713 fps= 20 q=32.0 size=    3901kB time=00:00:21.98 bitrate=1453.3kbits/
  
  frame=  723 fps= 20 q=32.0 size=    3969kB time=00:00:22.32 bitrate=1456.6kbits/
  
  frame=  735 fps= 20 q=32.0 size=    4027kB time=00:00:22.72 bitrate=1451.7kbits/
  
  frame=  744 fps= 20 q=32.0 size=    4102kB time=00:00:23.02 bitrate=1459.6kbits/
  
  frame=  755 fps= 20 q=32.0 size=    4135kB time=00:00:23.39 bitrate=1448.3kbits/
  
  frame=  764 fps= 20 q=32.0 size=    4172kB time=00:00:23.69 bitrate=1442.7kbits/
  
  frame=  776 fps= 20 q=32.0 size=    4216kB time=00:00:24.09 bitrate=1433.5kbits/
  
  frame=  787 fps= 20 q=32.0 size=    4254kB time=00:00:24.45 bitrate=1424.8kbits/
  
  frame=  802 fps= 20 q=32.0 size=    4337kB time=00:00:24.95 bitrate=1423.6kbits/
  
  frame=  815 fps= 20 q=32.0 size=    4369kB time=00:00:25.39 bitrate=1409.6kbits/
  
  frame=  828 fps= 20 q=32.0 size=    4450kB time=00:00:25.82 bitrate=1411.5kbits/
  
  frame=  840 fps= 20 q=32.0 size=    4467kB time=00:00:26.22 bitrate=1395.3kbits/
  
  frame=  852 fps= 20 q=32.0 size=    4550kB time=00:00:26.62 bitrate=1399.8kbits/
  
  frame=  865 fps= 20 q=32.0 size=    4594kB time=00:00:27.06 bitrate=1390.7kbits/
  
  frame=  877 fps= 20 q=32.0 size=    4629kB time=00:00:27.46 bitrate=1380.9kbits/
  
  frame=  889 fps= 20 q=32.0 size=    4689kB time=00:00:27.86 bitrate=1378.6kbits/
  
  frame=  900 fps= 20 q=32.0 size=    4740kB time=00:00:28.22 bitrate=1375.6kbits/
  
  frame=  901 fps= 19 q=-1.0 Lsize=    5203kB time=00:00:30.10 bitrate=1416.0kbits
  
  /s
  
  video:4586kB audio:590kB subtitle:0 global headers:0kB muxing overhead 0.532558%
  
  
  
  [libx264 @ 000000000264faa0] frame I:8     Avg QP:22.98  size: 31700
  
  [libx264 @ 000000000264faa0] frame P:893   Avg QP:27.55  size:  4974
  
  [libx264 @ 000000000264faa0] mb I  I16..4: 34.6%  0.0% 65.4%
  
  [libx264 @ 000000000264faa0] mb P  I16..4:  0.8%  0.0%  1.5%  P16..4: 41.4% 18.8
  
  %  8.5%  0.0%  0.0%    skip:29.0%
  
  [libx264 @ 000000000264faa0] final ratefactor: 24.50
  
  [libx264 @ 000000000264faa0] coded y,uvDC,uvAC intra: 64.3% 76.0% 36.7% inter: 2
  
  3.5% 19.6% 0.7%
  
  [libx264 @ 000000000264faa0] i16 v,h,dc,p: 34% 33% 11% 22%
  
  [libx264 @ 000000000264faa0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 12% 16% 12%  9% 12%
  
  11% 12%  7%  8%
  
  [libx264 @ 000000000264faa0] i8c dc,h,v,p: 55% 23% 14%  7%
  
  [libx264 @ 000000000264faa0] ref P L0: 72.3% 12.0%  8.1%  3.7%  3.9%
  
  [libx264 @ 000000000264faa0] kb/s:1249.53

  But still no luck. The .mp4 will play in every compatible device/browser combination I have tried except for chrome.. Any advice ?

  TIA.