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• More Cinepak Madness

  20 octobre 2011, par Multimedia Mike — Codec Technology

  Fellow digital archaeologist Clone2727 found a possible fifth variant of the Cinepak video codec. He asked me if I cared to investigate the sample. I assured him I wouldn’t be able to die a happy multimedia nerd unless I have cataloged all possible Cinepak variants known to exist in the wild. I’m sure there are chemistry nerds out there who are ecstatic when another element is added to the periodic table. Well, that’s me, except with weird multimedia formats.

  Background
  Cinepak is a video codec that saw widespread use in the early days of digital multimedia. To date, we have cataloged 4 variants of Cinepak in the wild. This distinction is useful when trying to write and maintain an all-in-one decoder. The variants are :

  1. The standard type : Most Cinepak data falls into this category. It decodes to a modified/simplified YUV 4:2:0 planar colorspace and is often seen in AVI and QuickTime/MOV files.
  2. 8-bit greyscale : Essentially the same as the standard type but with only a Y plane. This has only been identified in AVI files and is distinguished by the file header’s video bits/pixel field being set to 8 instead of 24.
  3. 8-bit paletted : Again, this is identified by the video header specifying 8 bits/pixel for a Cinepak stream. There is essentially only a Y plane in the data, however, each 8-bit value is a palette index. The palette is transported along with the video header. To date, only one known sample of this format has even been spotted in the wild, and it’s classified as NSFW. It is also a QuickTime/MOV file.
  4. Sega/FILM CPK data : Sega Saturn games often used CPK files which stored a variant of Cinepak that, while very close the standard Cinepak, couldn’t be decoded with standard decoder components.

  So, a flexible Cinepak decoder has to identify if the file’s video header specified 8 bits/pixel. How does it distinguish between greyscale and paletted ? If a file is paletted, a custom palette should have been included with the video header. Thus, if video bits/pixel is 8 and a palette is present, use paletted ; else, use greyscale. Beyond that, the Cinepak decoder has a heuristic to determine how to handle the standard type of data, which might deviate slightly if it comes from a Sega CPK file.

  The Fifth Variant ?
  Now, regarding this fifth variant– the reason this issue came up is because of that aforementioned heuristic. Basically, a Cinepak chunk is supposed to store the length of the entire chunk in its header. The data from a Sega CPK file plays fast and loose with this chunk size and the discrepancy makes it easy to determine if the data requires special handling. However, a handful of files discovered on a Macintosh game called “The Journeyman Project : Pegasus Prime” have chunk lengths which are sometimes in disagreement with the lengths reported in the containing QuickTime file’s stsz atom. This trips the heuristic and tries to apply the CPK rules against Cinepak data which, aside from the weird chunk length, is perfectly compliant.

  Here are the first few chunk sizes, as reported by the file header (stsz atom) and the chunk :

  size from stsz = 7880 (0x1EC8) ; from header = 3940 (0xF64)
  size from stsz = 3940 (0xF64) ; from header = 3940 (0xF64)
  size from stsz = 15792 (0x3DB0) ; from header = 3948 (0xF6C)
  size from stsz = 11844 (0x2E44) ; from header = 3948 (0xF6C)
  

  Hey, there’s a pattern here. If they don’t match, then the stsz size is an even multiple of the chunk size (2x, 3x, or 4x in my observation). I suppose I could revise the heuristic to state that if the stsz size is 2x, 3x, 4x, or equal to the chunk header, qualify it as compliant Cinepak data.

  Of course it feels impure, but software engineering is rarely about programmatic purity. A decade of special cases in the FFmpeg / Libav codebases are a testament to that.

  What’s A Variant ?
  Suddenly, I find myself contemplating what truly constitutes a variant. Maybe this was just a broken encoder program making these files ? And for that, I assign it the designation of distinct variation, like some sort of special, unique showflake ?

  Then again, I documented Magic Carpet FLIC as being a distinct variant of the broader FLIC format (which has an enormous number of variants as well).

• Embed Image into video - FFMPEG or JW player ?

  18 avril 2013, par Sri Kumar

  So I thought to embed the image as part of video content while converting the m4a to mp4. The output file has the image as video content and it plays as expected in VLC but when the same was streamed from my CDN using JW player, I do not see the image as video content, still it is black and audio is heard. Not sure what is the issue with embeding. I used the FFMPEG to embed image as video content.

  On the other hand is there any posibility with JW player to overlay an image as video content while audio can be heard in back end ?

• No audio encoded with ffmpeg using webm/libvorbis

  15 mars 2013, par Craig Lillard

  Having issues getting audio to encode to webm. Tried many different methods and it just ain't happenin. The commands are printed below before each pass.

  I have tried moving the audio commands around, trying different bitrates, different audio commands and have tried it on a couple of different files as well that both have audio.

  Encoding these files to MP4 using x264 causes no problems and works just fine and the audio plays, so it appears to be an issue just with webm. As you can see below, it is a 2-pass encode.

  Thanks for any help you can provide !

  Craig

  Webm LG PASS 1...........................
  
  
  
  
  
  
  
  
  
      webm_pass1: /usr/bin/ffmpeg -i /home/thedirectory/video613268.mov  -codec:v libvpx -quality good -vf 'scale=640:360 [scaled];movie=/home/thedirectory/watermarks/w640X360.png [logo];[scaled][logo] overlay' -cpu-used 0 -b:v 500k -aspect 16:9 -qmin 10 -qmax 42 -maxrate:v 500k -bufsize:v 1000k -r:v 25/1 -force_fps -threads 0 -an -acodec libvorbis -ac 2 -ab 96k -ar 44100 -pass 1 -f webm -y /dev/null
  
  
  
  
  
  
  
      ffmpeg version 0.10.2 Copyright (c) 2000-2012 the FFmpeg developers
  
        built on Mar 11 2013 14:48:26 with gcc 4.6.2 20111027 (Red Hat 4.6.2-2)
  
        configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man --incdir=/usr/include --disable-avisynth --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC' --enable-avfilter --enable-libfaac --enable-libgsm --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264 --enable-gpl --enable-nonfree --enable-postproc --enable-pthreads --enable-shared --enable-swscale --enable-vdpau --enable-version3 --enable-x11grab --enable-libvorbis --enable-libvpx
  
        libavutil      51. 35.100 / 51. 35.100
  
        libavcodec     53. 61.100 / 53. 61.100
  
        libavformat    53. 32.100 / 53. 32.100
  
        libavdevice    53.  4.100 / 53.  4.100
  
        libavfilter     2. 61.100 /  2. 61.100
  
        libswscale      2.  1.100 /  2.  1.100
  
        libswresample   0.  6.100 /  0.  6.100
  
        libpostproc    52.  0.100 / 52.  0.100
  
      Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/thedirectory/video613268.mov':
  
        Metadata:
  
          major_brand     : qt  
  
          minor_version   : 537199360
  
          compatible_brands: qt  
  
          creation_time   : 2013-02-23 20:04:32
  
        Duration: 00:00:21.02, start: 0.000000, bitrate: 114326 kb/s
  
          Stream #0:0(eng): Video: mjpeg (jpeg / 0x6765706A), yuvj422p, 1920x1080 [SAR 72:72 DAR 16:9], 112786 kb/s, 29.97 fps, 29.97 tbr, 2997 tbn, 2997 tbc
  
          Metadata:
  
            creation_time   : 2013-02-23 20:04:32
  
            handler_name    : ?Gestionnaire d?alias Apple
  
          Stream #0:1(eng): Audio: pcm_s16be (twos / 0x736F7774), 48000 Hz, 2 channels, s16, 1536 kb/s
  
          Metadata:
  
            creation_time   : 2013-02-23 20:04:32
  
            handler_name    : ?Gestionnaire d?alias Apple
  
      Incompatible pixel format 'yuvj422p' for codec 'libvpx', auto-selecting format 'yuv420p'
  
      [buffer @ 0x1f675a0] w:1920 h:1080 pixfmt:yuvj422p tb:1/1000000 sar:1/1 sws_param:
  
      [movie @ 0x1f799c0] seek_point:0 format_name:(null) file_name:/home/thedirectory/watermarks/w640X360.png stream_index:0
  
      [overlay @ 0x1f7c2c0] auto-inserting filter 'auto-inserted scale 0' between the filter 'Parsed_movie_1' and the filter 'Parsed_overlay_2'
  
      [scale @ 0x1f78d40] w:1920 h:1080 fmt:yuvj422p -> w:640 h:360 fmt:yuv420p flags:0x4
  
      [scale @ 0x1f7cde0] w:640 h:360 fmt:rgba -> w:640 h:360 fmt:yuva420p flags:0x4
  
      [overlay @ 0x1f7c2c0] main w:640 h:360 fmt:yuv420p overlay x:0 y:0 w:640 h:360 fmt:yuva420p
  
      [overlay @ 0x1f7c2c0] main_tb:1/1000000 overlay_tb:1/25 -> tb:1/1000000 exact:1
  
      [libvpx @ 0x1f77ce0] v1.0.0
  
      Output #0, webm, to '/dev/null':
  
        Metadata:
  
          major_brand     : qt  
  
          minor_version   : 537199360
  
          compatible_brands: qt  
  
          creation_time   : 2013-02-23 20:04:32
  
          encoder         : Lavf53.32.100
  
          Stream #0:0(eng): Video: vp8, yuv420p, 640x360 [SAR 1:1 DAR 16:9], q=10-42, pass 1, 500 kb/s, 1k tbn, 25 tbc
  
          Metadata:
  
            creation_time   : 2013-02-23 20:04:32
  
            handler_name    : ?Gestionnaire d?alias Apple
  
      Stream mapping:
  
        Stream #0:0 -> #0:0 (mjpeg -> libvpx)
  
      Press [q] to stop, [?] for help
  
      frame=  527 fps= 21 q=0.0 Lsize=       0kB time=00:00:00.00 bitrate=   0.0kbits/s dup=0 drop=103    
  
      video:0kB audio:0kB global headers:0kB muxing overhead -nan%
  
      Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)
  
      Webm LG PASS 2.......................
  
  
  
  
  
  
  
  
  
      webm_pass2: /usr/bin/ffmpeg -i /home/thedirectory/video613268.mov -codec:v libvpx -quality good -vf 'scale=640:360 [scaled];movie=/home/thedirectory/watermarks/w640X360.png [logo];[scaled][logo] overlay' -cpu-used 0 -b:v 500k  -aspect 16:9  -qmin 10 -qmax 42 -maxrate:v 500k -bufsize:v 1000k -r:v 24/1 -force_fps -threads 0 -an -acodec libvorbis -ac 2 -ab 96k -ar 44100 -pass 2 -f webm -y /media/amazons3/webmlg/video613268.mov.webm
  
  
  
  
  
  
  
      ffmpeg version 0.10.2 Copyright (c) 2000-2012 the FFmpeg developers
  
        built on Mar 11 2013 14:48:26 with gcc 4.6.2 20111027 (Red Hat 4.6.2-2)
  
        configuration: --prefix=/usr --libdir=/usr/lib64 --shlibdir=/usr/lib64 --mandir=/usr/share/man --incdir=/usr/include --disable-avisynth --extra-cflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC' --enable-avfilter --enable-libfaac --enable-libgsm --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264 --enable-gpl --enable-nonfree --enable-postproc --enable-pthreads --enable-shared --enable-swscale --enable-vdpau --enable-version3 --enable-x11grab --enable-libvorbis --enable-libvpx
  
        libavutil      51. 35.100 / 51. 35.100
  
        libavcodec     53. 61.100 / 53. 61.100
  
        libavformat    53. 32.100 / 53. 32.100
  
        libavdevice    53.  4.100 / 53.  4.100
  
        libavfilter     2. 61.100 /  2. 61.100
  
        libswscale      2.  1.100 /  2.  1.100
  
        libswresample   0.  6.100 /  0.  6.100
  
        libpostproc    52.  0.100 / 52.  0.100
  
      Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/thedirectory/video613268.mov':
  
        Metadata:
  
          major_brand     : qt  
  
          minor_version   : 537199360
  
          compatible_brands: qt  
  
          creation_time   : 2013-02-23 20:04:32
  
        Duration: 00:00:21.02, start: 0.000000, bitrate: 114326 kb/s
  
          Stream #0:0(eng): Video: mjpeg (jpeg / 0x6765706A), yuvj422p, 1920x1080 [SAR 72:72 DAR 16:9], 112786 kb/s, 29.97 fps, 29.97 tbr, 2997 tbn, 2997 tbc
  
          Metadata:
  
            creation_time   : 2013-02-23 20:04:32
  
            handler_name    : ?Gestionnaire d?alias Apple
  
          Stream #0:1(eng): Audio: pcm_s16be (twos / 0x736F7774), 48000 Hz, 2 channels, s16, 1536 kb/s
  
          Metadata:
  
            creation_time   : 2013-02-23 20:04:32
  
            handler_name    : ?Gestionnaire d?alias Apple
  
      Incompatible pixel format 'yuvj422p' for codec 'libvpx', auto-selecting format 'yuv420p'
  
      [buffer @ 0x1f2a5a0] w:1920 h:1080 pixfmt:yuvj422p tb:1/1000000 sar:1/1 sws_param:
  
      [movie @ 0x1f3bec0] seek_point:0 format_name:(null) file_name:/home/thedirectory/watermarks/w640X360.png stream_index:0
  
      [overlay @ 0x1f3f2c0] auto-inserting filter 'auto-inserted scale 0' between the filter 'Parsed_movie_1' and the filter 'Parsed_overlay_2'
  
      [scale @ 0x1f3c8a0] w:1920 h:1080 fmt:yuvj422p -> w:640 h:360 fmt:yuv420p flags:0x4
  
      [scale @ 0x1f3fde0] w:640 h:360 fmt:rgba -> w:640 h:360 fmt:yuva420p flags:0x4
  
      [overlay @ 0x1f3f2c0] main w:640 h:360 fmt:yuv420p overlay x:0 y:0 w:640 h:360 fmt:yuva420p
  
      [overlay @ 0x1f3f2c0] main_tb:1/1000000 overlay_tb:1/25 -> tb:1/1000000 exact:1
  
      [libvpx @ 0x1f3ace0] v1.0.0
  
      Output #0, webm, to '/media/amazons3/webmlg/video613268.mov.webm':
  
        Metadata:
  
          major_brand     : qt  
  
          minor_version   : 537199360
  
          compatible_brands: qt  
  
          creation_time   : 2013-02-23 20:04:32
  
          encoder         : Lavf53.32.100
  
          Stream #0:0(eng): Video: vp8, yuv420p, 640x360 [SAR 1:1 DAR 16:9], q=10-42, pass 2, 500 kb/s, 1k tbn, 24 tbc
  
          Metadata:
  
            creation_time   : 2013-02-23 20:04:32
  
            handler_name    : ?Gestionnaire d?alias Apple
  
      Stream mapping:
  
        Stream #0:0 -> #0:0 (mjpeg -> libvpx)
  
      Press [q] to stop, [?] for help
  
      frame=  506 fps=  7 q=0.0 Lsize=    1610kB time=00:00:21.08 bitrate= 625.8kbits/s dup=0 drop=124    
  
      video:1389kB audio:0kB global headers:0kB muxing overhead 15.952140%