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• ffmpeg determine correct codec to use

  6 janvier 2015, par nha

  I am trying to use .y4m files that I feed into Chrome for playing.
  This is the only format that I can use.

  I have a set of .y4m files that are working for my use case, taken from here.
  For example let’s say that I use the file mobile_qcif_7.5fps.y4m.

  I also have a .mp4 file (specifically the sample small.mp4 file from techslides ). I know how to convert small.mp4 to small.y4m with the following command :

  ffmpeg -y -i small.mp4 small.y4m

  I would like the resulting file to be accepted by Chrome, just like the other file.
  What options should I use (and how to find them) ?

  Additional information

  ffprobe gives :

  $ ffprobe small.y4m 
  
  avprobe version 0.8.13-6:0.8.13-0ubuntu0.13.10.1, Copyright (c) 2007-2014 the Libav developers
  
    built on Jul 15 2014 13:48:35 with gcc 4.8.1
  
  [yuv4mpegpipe @ 0x23160c0] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, yuv4mpegpipe, from 'small.y4m':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0.0: Video: rawvideo, yuv420p, 560x320, 30 fps, 30 tbr, 30 tbn, 30 tbc
  
  
  
  
  
  $ ffprobe mobile_qcif_7.5fps.y4m
  
  avprobe version 0.8.13-6:0.8.13-0ubuntu0.13.10.1, Copyright (c) 2007-2014 the Libav developers
  
    built on Jul 15 2014 13:48:35 with gcc 4.8.1
  
  [yuv4mpegpipe @ 0x1e080c0] max_analyze_duration reached
  
  [yuv4mpegpipe @ 0x1e080c0] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, yuv4mpegpipe, from 'mobile_qcif_7.5fps.y4m':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0.0: Video: rawvideo, yuv420p, 176x144, PAR 128:117 DAR 1408:1053, 7.50 fps, 7.50 tbr, 7.50 tbn, 7.50 tbc

  OS : I am using ffmpeg in Ubuntu 13.10 from the default repository : I ran sudo apt-get install ffmpeg libavcodec-extra-53

  Complete console output

  $ ffmpeg -y -i small.mp4 small.y4m
  
  ffmpeg version 0.8.13-6:0.8.13-0ubuntu0.13.10.1, Copyright (c) 2000-2014 the Libav developers
  
    built on Jul 15 2014 13:48:35 with gcc 4.8.1
  
  *** THIS PROGRAM IS DEPRECATED ***
  
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'small.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isomavc1
  
      creation_time   : 2010-03-20 21:29:11
  
      encoder         : HandBrake 0.9.4 2009112300
  
    Duration: 00:00:05.56, start: 0.000000, bitrate: 551 kb/s
  
      Stream #0.0(und): Video: h264 (Constrained Baseline), yuv420p, 560x320, 465 kb/s, 30 fps, 30 tbr, 90k tbn, 60 tbc
  
      Metadata:
  
        creation_time   : 2010-03-20 21:29:11
  
      Stream #0.1(eng): Audio: aac, 48000 Hz, mono, s16, 83 kb/s
  
      Metadata:
  
        creation_time   : 2010-03-20 21:29:11
  
  [buffer @ 0x7274e0] w:560 h:320 pixfmt:yuv420p
  
  Output #0, yuv4mpegpipe, to 'small.y4m':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isomavc1
  
      creation_time   : 2010-03-20 21:29:11
  
      encoder         : Lavf53.21.1
  
      Stream #0.0(und): Video: rawvideo, yuv420p, 560x320, q=2-31, 200 kb/s, 90k tbn, 30 tbc
  
      Metadata:
  
        creation_time   : 2010-03-20 21:29:11
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press ctrl-c to stop encoding
  
  frame=  166 fps=  0 q=0.0 Lsize=   43576kB time=5.53 bitrate=64513.5kbits/s    
  
  video:0kB audio:0kB global headers:0kB muxing overhead inf%

  Head of the files

  Not sure if this is relevant, but the text content of both files begin like that :

  mobile_qcif_7.5fps.y4m
  
  YUV4MPEG2 W176 H144 F15:2 Ip A128:117
  
  FRAME
  
  
  
  small.y4m (invalid)
  
  YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C420mpeg2 XYSCSS=420MPEG2
  
  FRAME

  Additional experiment

  Taking the sample mobile_qcif_7.5fps.y4m, turning it into a .mp4 file and then back into a .y4m produces an invalid file (at least for Chrome).

  Answer to comments in the answer of @SirDarius

  Following the suggestion of @SirDarius ; I tried the following commands.
  They failed to produce a valid file.

  # [COMMAND]   # [RESULT] [HEADER]
  
  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -pix_fmt yuv444p -y small_yuv444p.y4m   # KO YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C444 XYSCSS=444
  
  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -pix_fmt yuv422p -y small_yuv422p.y4m   # KO YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C422 XYSCSS=422
  
  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -pix_fmt yuv420p -y small_yuv420p.y4m   # KO YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C420mpeg2 XYSCSS=420MPEG2
  
  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -pix_fmt yuv411p -y small_yuv411p.y4m   # KO   YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C411 XYSCSS=411
  
  
  
  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -strict -1 -pix_fmt yuv420p9 -y small_yuv420p9.y4m   # KO YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C420p9 XYSCSS=420P9
  
  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -strict -1 -pix_fmt yuv420p12 -y small_yuv420p12.y4m # KO YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C420p12 XYSCSS=420P12
  
  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -strict -1 -pix_fmt yuv420p14 -y small_yuv420p14.y4m # KO YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C420p14 XYSCSS=420P14
  
  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -strict -1 -pix_fmt yuv420p16 -y small_yuv420p16.y4m # KO YUV4MPEG2 W560 H320 F15:2 Ip A0:0 C420p16 XYSCSS=420P16

  When trying other formats (like yuv420p12be, which was in the output of -pix_fmts), I had the following output (hence my previous trials) :

  $  ffmpeg -i small.mp4 -vf fps=7.5 -an -c:v rawvideo -f yuv4mpegpipe -pix_fmt yuv420p12be -y small_yuv420p12be.y4m 
  
  ffmpeg version N-68884-g3ebd76a Copyright (c) 2000-2015 the FFmpeg developers
  
    built on Jan  6 2015 11:03:21 with gcc 4.8 (Ubuntu/Linaro 4.8.1-10ubuntu9)
  
    configuration: 
  
    libavutil      54. 16.100 / 54. 16.100
  
    libavcodec     56. 19.100 / 56. 19.100
  
    libavformat    56. 18.100 / 56. 18.100
  
    libavdevice    56.  3.100 / 56.  3.100
  
    libavfilter     5.  6.100 /  5.  6.100
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  1.100 /  1.  1.100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x21d0220] overread end of atom 'colr' by 1 bytes
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'small.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isomavc1
  
      creation_time   : 2010-03-20 21:29:11
  
      encoder         : HandBrake 0.9.4 2009112300
  
    Duration: 00:00:05.57, start: 0.000000, bitrate: 551 kb/s
  
      Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p(tv, bt709), 560x320, 465 kb/s, 30 fps, 30 tbr, 90k tbn, 60 tbc (default)
  
      Metadata:
  
        creation_time   : 2010-03-20 21:29:11
  
        encoder         : JVT/AVC Coding
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, mono, fltp, 83 kb/s (default)
  
      Metadata:
  
        creation_time   : 2010-03-20 21:29:11
  
  [yuv4mpegpipe @ 0x21d8180] ERROR: yuv4mpeg can only handle yuv444p, yuv422p, yuv420p, yuv411p and gray8 pixel formats. And using 'strict -1' also yuv444p9, yuv422p9, yuv420p9, yuv444p10, yuv422p10, yuv420p10, yuv444p12, yuv422p12, yuv420p12, yuv444p14, yuv422p14, yuv420p14, yuv444p16, yuv422p16, yuv420p16 and gray16 pixel formats. Use -pix_fmt to select one.
  
  Output #0, yuv4mpegpipe, to 'small_yuv420p12be.y4m':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: mp42isomavc1
  
      encoder         : Lavf56.18.100
  
      Stream #0:0(und): Video: rawvideo ([12][11]3Y / 0x59330B0C), yuv420p12be, 560x320, q=2-31, 200 kb/s, 7.50 fps, 7.50 tbn, 7.50 tbc (default)
  
      Metadata:
  
        creation_time   : 2010-03-20 21:29:11
  
        encoder         : Lavc56.19.100 rawvideo
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
  
  Could not write header for output file #0 (incorrect codec parameters ?): Input/output error

  After that, I also tried to edit with an hexadecimal editor (bless) the small_yuv420p.y4m file. I replace C420mpeg2 by C420, and the file was accepted by Chrome.
  What does the number in 420p[number] correspond to ? It is not explained there.
  Is there any way to make ffmpeg output this kind of header files ?

  @SirDarius, thank you again for your help.

  The question

  (in case you forgot after this text blob)

  How can I convert the small.mp4 into a small.y4m file that has the same properties as the mobile_qcif_7.5fps.y4m file ?

• Anomalie #3373 (Nouveau) : Erreur "PHP Strict Standards" dans inc\syndic.php

  12 janvier 2015, par Eric Camus

  SPIP 3.0.17, sites 1.7.13 sur IIS 6 + PHP 5.4.35

  La ligne du fichier "inc\syndic.php" :
         $lang = reset(explode("-",$lang));

  Rempli nos log d’erreur PHP de :
  [11-Jan-2015 21:18:44 Europe/Paris] PHP Strict Standards:  Only variables should be passed by reference in D:\xxxxx\yyyyy\plugins-dist\sites\inc\syndic.php on line 329

  Modification proposé :
         $buf=explode("-",$lang);
       $lang = reset($buf);

• Trolls in trouble

  6 juin 2013, par Mans — Law and liberty

  Life as a patent troll is hopefully set to get more difficult. In a memo describing patent trolls as a “drain on the American economy,” the White House this week outlined a number of steps it is taking to stem this evil tide. Chiming in, the Chief Judge of the Court of Appeals for the Federal Circuit (where patent cases are heard) in a New York Times op-ed laments the toll patent trolling is taking on the industry, and urges judges to use powers already at their disposal to make the practice less attractive. However, while certainly a step in the right direction, these measures all fail to address the more fundamental properties of the patent system allowing trolls to exist in the first place.

  System and method for patent trolling

  Most patent trolling operations comprise the same basic elements :

  1. One or more patents with broad claims.
  2. The patents of (1) acquired by an otherwise non-practising entity (troll).
  3. The entity of (2) filing numerous lawsuits alleging infringement of the patents of (1).
  4. The lawsuits of (3) targeting end users or retailers.
  5. The lawsuits of (3) listing as plaintiffs difficult to trace shell companies.

  The recent legislative actions all take aim at the latter entries in this list. In so doing, they will no doubt cripple the trolls, but the trolls will remain alive, ready to resume their wicked ways once a new loophole is found in the system.

  To kill a patent troll

  As Judge Rader and his co-authors point out in the New York Times, “the problem stems largely from the fact that, [...] trolls have an important strategic advantage over their adversaries : they don’t make anything.” This is the heart of the troll, and this is where the blow should be struck. Our weapon shall be the mightiest judicial sword of all, the Constitution.

  The United States Constitution contains (in Article I, Section 8) the foundation for the patent system (emphasis mine) :

  The Congress shall have Power [...] To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.

  Patent trolls are typically not inventors. They are merely hoarders of other people’s discarded inventions, and that allowing others to reap the benefits of an inventor’s work would somehow promote progress should be a tough argument. Indeed, it is the dissociation between investment and reward which has allowed the patent trolls to rise and prosper.

  In light of the above, the solution to the troll menace is actually strikingly simple : make patents non-transferable.

  Having the inventor retain the rights to his or her inventions (works for hire still being recognised), would render the establishment of non-practising entities, which most trolls are, virtually impossible. The original purpose of patents, to protect the investment of inventors, would remain unaffected, if not strengthened, by such a change.

  Links

  • Taking on Patent Trolls to Protect American Innovation
  • Fact Sheet : White House Task Force on High-Tech Patent Issues
  • Make Patent Trolls Pay in Court
  • Constitution of the United States