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  • Why JPEG image looks different in two videos ?

    28 septembre 2015, par user606521

    I have two frames :

    f1.jpg
    f1.jpg
    f2.jpg
    f2.jpg

    And I am creating two videos :

    ./ffmpeg -i ./f%d.jpg -r 30 -y m1.mp4 # both frames 1 and 2
    
./ffmpeg -i ./f2.jpg -r 30 -y m2.mp4 # only frame 2

    For some reason frame 2 looks different in these two videos

    Frame 2 from m1.mp4 :

    $ ./ffmpeg -i m1.mp4 out1_%d.jpg
    
ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
    
  built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
    
  configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc --arch=x86_64 --enable-runtime-cpudetect
    
  libavutil      54. 27.100 / 54. 27.100
    
  libavcodec     56. 41.100 / 56. 41.100
    
  libavformat    56. 36.100 / 56. 36.100
    
  libavdevice    56.  4.100 / 56.  4.100
    
  libavfilter     5. 16.101 /  5. 16.101
    
  libswscale      3.  1.101 /  3.  1.101
    
  libswresample   1.  2.100 /  1.  2.100
    
  libpostproc    53.  3.100 / 53.  3.100
    
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'm1.mp4':
    
  Metadata:
    
    major_brand     : isom
    
    minor_version   : 512
    
    compatible_brands: isomiso2avc1mp41
    
    encoder         : Lavf56.36.100
    
  Duration: 00:00:00.07, start: 0.000000, bitrate: 478 kb/s
    
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 980x100, 381 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    
    Metadata:
    
      handler_name    : VideoHandler
    
[swscaler @ 0x7f7f9a000600] deprecated pixel format used, make sure you did set range correctly
    
Output #0, image2, to 'out1_%d.jpg':
    
  Metadata:
    
    major_brand     : isom
    
    minor_version   : 512
    
    compatible_brands: isomiso2avc1mp41
    
    encoder         : Lavf56.36.100
    
    Stream #0:0(und): Video: mjpeg, yuvj420p(pc), 980x100, q=2-31, 200 kb/s, 30 fps, 30 tbn, 30 tbc (default)
    
    Metadata:
    
      handler_name    : VideoHandler
    
      encoder         : Lavc56.41.100 mjpeg
    
Stream mapping:
    
  Stream #0:0 -> #0:0 (h264 (native) -> mjpeg (native))
    
Press [q] to stop, [?] for help
    
frame=    2 fps=0.0 q=1.6 Lsize=N/A time=00:00:00.06 bitrate=N/A    
    
video:6kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

    f1_out.jpg

    Frame 2 from m2.mp4 :

    $ ./ffmpeg -i m2.mp4 out2_%d.jpg
    
ffmpeg version 2.7.2 Copyright (c) 2000-2015 the FFmpeg developers
    
  built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
    
  configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc --arch=x86_64 --enable-runtime-cpudetect
    
  libavutil      54. 27.100 / 54. 27.100
    
  libavcodec     56. 41.100 / 56. 41.100
    
  libavformat    56. 36.100 / 56. 36.100
    
  libavdevice    56.  4.100 / 56.  4.100
    
  libavfilter     5. 16.101 /  5. 16.101
    
  libswscale      3.  1.101 /  3.  1.101
    
  libswresample   1.  2.100 /  1.  2.100
    
  libpostproc    53.  3.100 / 53.  3.100
    
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'm2.mp4':
    
  Metadata:
    
    major_brand     : isom
    
    minor_version   : 512
    
    compatible_brands: isomiso2avc1mp41
    
    encoder         : Lavf56.36.100
    
  Duration: 00:00:00.03, start: 0.000000, bitrate: 824 kb/s
    
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc), 980x100 [SAR 1:1 DAR 49:5], 648 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    
    Metadata:
    
      handler_name    : VideoHandler
    
Output #0, image2, to 'out2_%d.jpg':
    
  Metadata:
    
    major_brand     : isom
    
    minor_version   : 512
    
    compatible_brands: isomiso2avc1mp41
    
    encoder         : Lavf56.36.100
    
    Stream #0:0(und): Video: mjpeg, yuvj420p(pc), 980x100 [SAR 1:1 DAR 49:5], q=2-31, 200 kb/s, 30 fps, 30 tbn, 30 tbc (default)
    
    Metadata:
    
      handler_name    : VideoHandler
    
      encoder         : Lavc56.41.100 mjpeg
    
Stream mapping:
    
  Stream #0:0 -> #0:0 (h264 (native) -> mjpeg (native))
    
Press [q] to stop, [?] for help
    
frame=    1 fps=0.0 q=1.6 Lsize=N/A time=00:00:00.03 bitrate=N/A    
    
video:4kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

    f2_out.jpg

    It seems that frame 2 looks different when combined with frame 1 in a video. One thing I noticed that when dumping frames from m1.mp4 (two frames combined) there is a warning in ffmpeg output :

    [swscaler @ 0x7f7f9a000600] deprecated pixel format used, make sure you did set range correctly

    Also two frame images have same dimmensions (980x100) and their format seems to be same :

    $ file -b f1.jpg
    
JPEG image data, JFIF standard 1.01, comment: "CS=ITU601??"
    
$ file -b f2.jpg 
    
JPEG image data, JFIF standard 1.01

    So why this is happening ? I am struggling with this issue for quite a long time - for some reason some JPEGs somehow are in different "format ?" than others and make mess in videos...

    You can download first two images included in this question and test commands on your own.

    $ identify -verbose f1.jpg
    
Image: f1.jpg
    
  Format: JPEG (Joint Photographic Experts Group JFIF format)
    
  Mime type: image/jpeg
    
  Class: DirectClass
    
  Geometry: 980x100+0+0
    
  Resolution: 552x551
    
  Print size: 1.77536x0.181488
    
  Units: PixelsPerInch
    
  Type: Palette
    
  Endianess: Undefined
    
  Colorspace: sRGB
    
  Depth: 8-bit
    
  Channel depth:
    
    red: 8-bit
    
    green: 8-bit
    
    blue: 8-bit
    
  Channel statistics:
    
    Red:
    
      min: 189 (0.741176)
    
      max: 233 (0.913725)
    
      mean: 208.261 (0.81671)
    
      standard deviation: 14.1741 (0.0555848)
    
      kurtosis: -1.40078
    
      skewness: 0.332664
    
    Green:
    
      min: 189 (0.741176)
    
      max: 233 (0.913725)
    
      mean: 208.261 (0.81671)
    
      standard deviation: 14.1741 (0.0555848)
    
      kurtosis: -1.40078
    
      skewness: 0.332664
    
    Blue:
    
      min: 189 (0.741176)
    
      max: 233 (0.913725)
    
      mean: 208.26 (0.816706)
    
      standard deviation: 14.1756 (0.0555905)
    
      kurtosis: -1.40068
    
      skewness: 0.332424
    
  Image statistics:
    
    Overall:
    
      min: 189 (0.741176)
    
      max: 233 (0.913725)
    
      mean: 208.261 (0.816709)
    
      standard deviation: 14.1746 (0.0555867)
    
      kurtosis: -1.40075
    
      skewness: 0.332584
    
  Colors: 47
    
  Histogram:
    
       368: (189,189,189) #BDBDBD grey74
    
      1984: (190,190,190) #BEBEBE grey
    
        28: (191,191,189) #BFBFBD srgb(191,191,189)
    
      3780: (191,191,191) #BFBFBF grey75
    
        28: (192,192,190) #C0C0BE srgb(192,192,190)
    
      6628: (192,192,192) #C0C0C0 silver
    
      5664: (193,193,193) #C1C1C1 srgb(193,193,193)
    
      4608: (194,194,194) #C2C2C2 grey76
    
      4480: (195,195,195) #C3C3C3 srgb(195,195,195)
    
      3328: (196,196,196) #C4C4C4 grey77
    
      2592: (197,197,197) #C5C5C5 srgb(197,197,197)
    
      3072: (198,198,198) #C6C6C6 srgb(198,198,198)
    
      2272: (199,199,199) #C7C7C7 grey78
    
      2112: (200,200,200) #C8C8C8 srgb(200,200,200)
    
      2112: (201,201,201) #C9C9C9 grey79
    
      1920: (202,202,202) #CACACA srgb(202,202,202)
    
      1728: (203,203,203) #CBCBCB srgb(203,203,203)
    
      1760: (204,204,204) #CCCCCC grey80
    
      1696: (205,205,205) #CDCDCD srgb(205,205,205)
    
      1248: (206,206,206) #CECECE srgb(206,206,206)
    
      1536: (207,207,207) #CFCFCF grey81
    
      1504: (208,208,208) #D0D0D0 srgb(208,208,208)
    
      1344: (209,209,209) #D1D1D1 grey82
    
      1536: (210,210,210) #D2D2D2 srgb(210,210,210)
    
      1472: (211,211,211) #D3D3D3 LightGray
    
      1088: (212,212,212) #D4D4D4 grey83
    
      1472: (213,213,213) #D5D5D5 srgb(213,213,213)
    
      1536: (214,214,214) #D6D6D6 grey84
    
      1344: (215,215,215) #D7D7D7 srgb(215,215,215)
    
      1184: (216,216,216) #D8D8D8 srgb(216,216,216)
    
      1408: (217,217,217) #D9D9D9 grey85
    
      1472: (218,218,218) #DADADA srgb(218,218,218)
    
      1216: (219,219,219) #DBDBDB grey86
    
      1280: (220,220,220) #DCDCDC gainsboro
    
      1536: (221,221,221) #DDDDDD srgb(221,221,221)
    
      1472: (222,222,222) #DEDEDE grey87
    
      1600: (223,223,223) #DFDFDF srgb(223,223,223)
    
      1696: (224,224,224) #E0E0E0 grey88
    
      1792: (225,225,225) #E1E1E1 srgb(225,225,225)
    
      1728: (226,226,226) #E2E2E2 srgb(226,226,226)
    
      1952: (227,227,227) #E3E3E3 grey89
    
      2272: (228,228,228) #E4E4E4 srgb(228,228,228)
    
      2752: (229,229,229) #E5E5E5 grey90
    
      4512: (230,230,230) #E6E6E6 srgb(230,230,230)
    
      4672: (231,231,231) #E7E7E7 srgb(231,231,231)
    
       640: (232,232,232) #E8E8E8 grey91
    
       576: (233,233,233) #E9E9E9 srgb(233,233,233)
    
  Rendering intent: Perceptual
    
  Gamma: 0.454545
    
  Chromaticity:
    
    red primary: (0.64,0.33)
    
    green primary: (0.3,0.6)
    
    blue primary: (0.15,0.06)
    
    white point: (0.3127,0.329)
    
  Background color: white
    
  Border color: srgb(223,223,223)
    
  Matte color: grey74
    
  Transparent color: black
    
  Interlace: None
    
  Intensity: Undefined
    
  Compose: Over
    
  Page geometry: 980x100+0+0
    
  Dispose: Undefined
    
  Iterations: 0
    
  Compression: JPEG
    
  Orientation: Undefined
    
  Properties:
    
    comment: CS=ITU601
    
    date:create: 2015-09-28T21:47:26+02:00
    
    date:modify: 2015-09-28T21:47:26+02:00
    
    jpeg:colorspace: 2
    
    jpeg:quality: 92
    
    jpeg:sampling-factor: 2x2,1x1,1x1
    
    signature: ca599d8ad07c79b36837cb9f4811d83e236b8d4a4cdfada8d60c4aa330f28f38
    
  Artifacts:
    
    filename: f1.jpg
    
    verbose: true
    
  Tainted: False
    
  Filesize: 1.36KB
    
  Number pixels: 98K
    
  Pixels per second: 9.8MB
    
  User time: 0.000u
    
  Elapsed time: 0:01.009
    
  Version: ImageMagick 6.8.7-0 2013-10-28 Q16 http://www.imagemagick.org
    $ identify -verbose f2.jpg
    
Image: f2.jpg
    
  Format: JPEG (Joint Photographic Experts Group JFIF format)
    
  Mime type: image/jpeg
    
  Class: DirectClass
    
  Geometry: 980x100+0+0
    
  Resolution: 72x72
    
  Print size: 13.6111x1.38889
    
  Units: PixelsPerInch
    
  Type: Palette
    
  Endianess: Undefined
    
  Colorspace: sRGB
    
  Depth: 8-bit
    
  Channel depth:
    
    red: 8-bit
    
    green: 8-bit
    
    blue: 8-bit
    
  Channel statistics:
    
    Red:
    
      min: 186 (0.729412)
    
      max: 254 (0.996078)
    
      mean: 242.844 (0.952329)
    
      standard deviation: 11.0845 (0.0434688)
    
      kurtosis: 4.24417
    
      skewness: -2.17102
    
    Green:
    
      min: 186 (0.729412)
    
      max: 254 (0.996078)
    
      mean: 242.844 (0.952329)
    
      standard deviation: 11.0845 (0.0434688)
    
      kurtosis: 4.24417
    
      skewness: -2.17102
    
    Blue:
    
      min: 186 (0.729412)
    
      max: 254 (0.996078)
    
      mean: 242.842 (0.952323)
    
      standard deviation: 11.0886 (0.0434848)
    
      kurtosis: 4.24235
    
      skewness: -2.17103
    
  Image statistics:
    
    Overall:
    
      min: 186 (0.729412)
    
      max: 254 (0.996078)
    
      mean: 242.843 (0.952327)
    
      standard deviation: 11.0859 (0.0434741)
    
      kurtosis: 4.24356
    
      skewness: -2.17102
    
  Colors: 91
    
  Histogram:
    
         2: (186,186,186) #BABABA grey73
    
         2: (187,187,187) #BBBBBB srgb(187,187,187)
    
         1: (189,189,189) #BDBDBD grey74
    
         5: (190,190,190) #BEBEBE grey
    
         2: (191,191,191) #BFBFBF grey75
    
        20: (192,192,192) #C0C0C0 silver
    
        28: (193,193,193) #C1C1C1 srgb(193,193,193)
    
        37: (194,194,194) #C2C2C2 grey76
    
        46: (195,195,195) #C3C3C3 srgb(195,195,195)
    
        59: (196,196,196) #C4C4C4 grey77
    
       108: (197,197,197) #C5C5C5 srgb(197,197,197)
    
       134: (198,198,198) #C6C6C6 srgb(198,198,198)
    
       145: (199,199,199) #C7C7C7 grey78
    
       188: (200,200,200) #C8C8C8 srgb(200,200,200)
    
       230: (201,201,201) #C9C9C9 grey79
    
       241: (202,202,202) #CACACA srgb(202,202,202)
    
       236: (203,203,203) #CBCBCB srgb(203,203,203)
    
       252: (204,204,204) #CCCCCC grey80
    
       240: (205,205,205) #CDCDCD srgb(205,205,205)
    
       243: (206,206,206) #CECECE srgb(206,206,206)
    
         1: (207,207,205) #CFCFCD srgb(207,207,205)
    
       250: (207,207,207) #CFCFCF grey81
    
         1: (208,208,206) #D0D0CE srgb(208,208,206)
    
       267: (208,208,208) #D0D0D0 srgb(208,208,208)
    
         2: (209,209,207) #D1D1CF srgb(209,209,207)
    
       226: (209,209,209) #D1D1D1 grey82
    
         3: (210,210,208) #D2D2D0 srgb(210,210,208)
    
       193: (210,210,210) #D2D2D2 srgb(210,210,210)
    
         5: (211,211,209) #D3D3D1 srgb(211,211,209)
    
       215: (211,211,211) #D3D3D3 LightGray
    
         7: (212,212,210) #D4D4D2 srgb(212,212,210)
    
       227: (212,212,212) #D4D4D4 grey83
    
        11: (213,213,211) #D5D5D3 srgb(213,213,211)
    
       250: (213,213,213) #D5D5D5 srgb(213,213,213)
    
         4: (214,214,212) #D6D6D4 srgb(214,214,212)
    
       291: (214,214,214) #D6D6D6 grey84
    
        16: (215,215,213) #D7D7D5 srgb(215,215,213)
    
       307: (215,215,215) #D7D7D7 srgb(215,215,215)
    
         1: (216,216,214) #D8D8D6 srgb(216,216,214)
    
       371: (216,216,216) #D8D8D8 srgb(216,216,216)
    
         4: (217,217,215) #D9D9D7 srgb(217,217,215)
    
       355: (217,217,217) #D9D9D9 grey85
    
         3: (218,218,216) #DADAD8 srgb(218,218,216)
    
       398: (218,218,218) #DADADA srgb(218,218,218)
    
         3: (219,219,217) #DBDBD9 srgb(219,219,217)
    
       404: (219,219,219) #DBDBDB grey86
    
         5: (220,220,218) #DCDCDA srgb(220,220,218)
    
       435: (220,220,220) #DCDCDC gainsboro
    
         1: (221,221,219) #DDDDDB srgb(221,221,219)
    
       489: (221,221,221) #DDDDDD srgb(221,221,221)
    
         2: (222,222,220) #DEDEDC srgb(222,222,220)
    
       569: (222,222,222) #DEDEDE grey87
    
         1: (223,223,221) #DFDFDD srgb(223,223,221)
    
       552: (223,223,223) #DFDFDF srgb(223,223,223)
    
         2: (224,224,222) #E0E0DE srgb(224,224,222)
    
       595: (224,224,224) #E0E0E0 grey88
    
         2: (225,225,223) #E1E1DF srgb(225,225,223)
    
       645: (225,225,225) #E1E1E1 srgb(225,225,225)
    
       736: (226,226,226) #E2E2E2 srgb(226,226,226)
    
         3: (227,227,225) #E3E3E1 srgb(227,227,225)
    
       646: (227,227,227) #E3E3E3 grey89
    
         1: (228,228,226) #E4E4E2 srgb(228,228,226)
    
       707: (228,228,228) #E4E4E4 srgb(228,228,228)
    
         1: (229,229,227) #E5E5E3 srgb(229,229,227)
    
       667: (229,229,229) #E5E5E5 grey90
    
         1: (230,230,228) #E6E6E4 srgb(230,230,228)
    
       759: (230,230,230) #E6E6E6 srgb(230,230,230)
    
       767: (231,231,231) #E7E7E7 srgb(231,231,231)
    
       788: (232,232,232) #E8E8E8 grey91
    
       862: (233,233,233) #E9E9E9 srgb(233,233,233)
    
       880: (234,234,234) #EAEAEA srgb(234,234,234)
    
       889: (235,235,235) #EBEBEB grey92
    
       863: (236,236,236) #ECECEC srgb(236,236,236)
    
       868: (237,237,237) #EDEDED grey93
    
      1032: (238,238,238) #EEEEEE srgb(238,238,238)
    
       878: (239,239,239) #EFEFEF srgb(239,239,239)
    
      1083: (240,240,240) #F0F0F0 grey94
    
      1035: (241,241,241) #F1F1F1 srgb(241,241,241)
    
      1247: (242,242,242) #F2F2F2 grey95
    
      1610: (243,243,243) #F3F3F3 srgb(243,243,243)
    
      2084: (244,244,244) #F4F4F4 srgb(244,244,244)
    
      3473: (245,245,245) #F5F5F5 grey96
    
      6350: (246,246,246) #F6F6F6 srgb(246,246,246)
    
      9152: (247,247,247) #F7F7F7 grey97
    
     14755: (248,248,248) #F8F8F8 srgb(248,248,248)
    
     21183: (249,249,249) #F9F9F9 srgb(249,249,249)
    
     12507: (250,250,250) #FAFAFA grey98
    
      2516: (251,251,251) #FBFBFB srgb(251,251,251)
    
       305: (252,252,252) #FCFCFC grey99
    
        16: (253,253,253) #FDFDFD srgb(253,253,253)
    
         4: (254,254,254) #FEFEFE srgb(254,254,254)
    
  Rendering intent: Perceptual
    
  Gamma: 0.454545
    
  Chromaticity:
    
    red primary: (0.64,0.33)
    
    green primary: (0.3,0.6)
    
    blue primary: (0.15,0.06)
    
    white point: (0.3127,0.329)
    
  Background color: white
    
  Border color: srgb(223,223,223)
    
  Matte color: grey74
    
  Transparent color: black
    
  Interlace: None
    
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  Page geometry: 980x100+0+0
    
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  Iterations: 0
    
  Compression: JPEG
    
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    date:create: 2015-09-28T21:48:30+02:00
    
    date:modify: 2015-09-28T21:48:30+02:00
    
    jpeg:colorspace: 2
    
    jpeg:quality: 92
    
    jpeg:sampling-factor: 2x2,1x1,1x1
    
    signature: f718ab157fae4ff0395eaf07a0165897fd9de558eaed00586530690d39e5ed23
    
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    filename: f2.jpg
    
    verbose: true
    
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  Number pixels: 98K
    
  Pixels per second: 0B
    
  User time: 0.000u
    
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  Version: ImageMagick 6.8.7-0 2013-10-28 Q16 http://www.imagemagick.org

  • Giving Thanks For VP8

    25 novembre 2010, par Multimedia Mike — VP8

    It’s the Thanksgiving holiday here in the United States. I guess that’s as good a reason as any to release a first cut of my VP8 encoder. In order to remind people that they shouldn’t expect phenomenal quality from it — and to discourage inexperienced people from trying to create useful videos with it — I have hardcoded the quantizers to their maximum settings. For those not skilled in the art, this is the setting that yields maximum compression and worst quality. When compressing the Big Buck Bunny logo image, the resulting file is only 2839 bytes but observe the reconstructed quality :



    It really just looks like a particularly stormy day in the forest.

    First VP8 File From An Independent Encoder
    I found a happy medium on the quantizer scale and encoded the first 30 seconds of Big Buck Bunny for your inspection. I guess this makes it the first VP8/WebM file from an independent encoder (using FFmpeg’s Matroska muxer as well).

    Download : bbb-360p-30sec-q40.webm ( 13 MBytes)

    I think the quality makes it look like it was digitized from an old VHS tape.

    For fun, here’s the version with the quantizer cranked to the max : bbb-360p-30sec-q127.webm ( 1.3 MBytes)

    Aside : I was going to encapsulate the video in this post using a bare HTML5 <video> tag for the benefit of the small browsing population who could view that (indeed, it works fine in Chrome). But that would be insane due to the fact that supporting browsers preload the video with no easy (read : without the help of JavaScript) method for overriding this unacceptable default.

    The Code
    I’m still trying to get over my fear of git. To that end, I have posted the code on Github :

    https://github.com/multimediamike/ffvp8enc

    I still don’t like you, git. But I’m sure we’ll find some way to make this work.

    Other required code changes in the basic FFmpeg tree :

    • Of course, copy vp8enc.c into libavcodec/
    • In libavcodec/allcodecs.c, ’REGISTER_DECODER (VP8, vp8);’ turns into ’REGISTER_ENCDEC (VP8, vp8);’
    • Add ’OBJS-$(CONFIG_VP8_ENCODER) += vp8enc.o’ to libavcodec/Makefile

    Further Work
    About the limitations and work yet to do :

    • it’s still intra-only, no interframes (which is where a lot of compression occurs)
    • no rate control or distortion optimization, obviously
    • no intra 4x4 coding (that’s close to working but didn’t my little T-day deadline)
    • no quantization control ; this should really be hooked up to the FFmpeg command line but I’m not sure how
    • encoder writes into a static-sized, 1/2 MB memory buffer ; this can overflow
    • code is a mess (what did you expect at this stage of the game ?)
    • lots and lots of other things, surely

  • mov : Fix handling of zero-length metadata values

    15 décembre 2014, par Martin Storsjö
    mov : Fix handling of zero-length metadata values

    Since 3cec81f4d4, a zero-length metadata value would try to
    
allocate 2*0 bytes, where av_malloc() returns NULL.
    

    Always add one to the allocated length, to allow space for
    
a null terminator in the zero-length case.
    

    Incidentally, this fixes fate-alac on RVCT 4.0, where a compiler
    
bug seems to mess up the mov muxer to the point that it writes
    
the wrong sort of metadata. Previously this bug was undetected,
    
but since 3cec81f4d4 such mov files started returning
    
AVERROR(ENOMEM) in the mov demuxer.
    

    Signed-off-by : Martin Storsjö <martin@martin.st>
    • [DH] libavformat/mov.c

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