Recherche avancée

Sur d’autres sites (6882)

• Compressed SWF format not supported/cws2fws issue

  16 septembre 2011, par CodedMonkey

  I am trying to convert .swf to a .flv file using ffmpeg. When I got that error, I searched around and found that I should use cws2fws to somehow decompress the .swf file so that it can be converted by ffmpeg. However, apparently I need to compile the cws2fws.c myself, but it requires so many other libs and files and none of them are located on any 1 site. Is there a precompiled version of cws2fws available somewhere for download, or can I solved my initial error some other way ?

• Dreamcast Operating Systems

  16 septembre 2010, par Multimedia Mike — Sega Dreamcast

  The Sega Dreamcast was famously emblazoned with a logo proudly announcing that it was compatible with Windows CE :

  
  
  

  It’s quite confusing. The console certainly doesn’t boot into some version of Windows to launch games. Apparently, there was a special version of CE developed for the DC and game companies had the option to leverage it. I do recall that some game startup screens would similarly advertise Windows CE.

  Once the homebrew community got ahold of the device, the sky was the limit. I think NetBSD was the first alternative OS to support the Dreamcast. Meanwhile, I have recollections of DC Linux and LinuxDC projects along with more generic Linux-SH and SH-Linux projects.

  
  
  

  DC Evolution hosts a disc image available for download with an unofficial version of DC Linux, assembled by one Adrian O’Grady. I figured out how to burn the disc (burning DC discs is a blog post of its own) and got it working in the console.

  It’s possible to log in directly via the physical keyboard or through a serial terminal provided that you have a coder’s cable. That reminds me– my local Fry’s had a selection of USB-to-serial cables. I think this is another area that is sufficiently commoditized that just about any cable ought to work with Linux out of the box. Or maybe I’m just extrapolating from the experience of having the cheapest cable in the selection (made by io connect) plug and play with Linux.

  
  
  

  Look ! No messy converter box in the middle as in the Belkin case. The reason I went with this cable is that the packaging claimed it was capable of up to 500 Kbits/sec. Most of the cables advertised a max of 115200 bps. I distinctly recall being able to use the DC coder’s cable at 230400 bps a long time ago. Alas, 115200 seems to be the speed limit, even with this new USB cable.

  Anyway, the distribution is based on a 2.4.5 kernel circa 2001. I tried to make PPP work over the serial cable but the kernel doesn’t have support. If you’re interested, here is some basic information about the machine from Linux’s perspective, gleaned from some simple commands. This helps remind us of a simpler time when Linux was able to run comfortably on a computer with 16 MB of RAM.

  Debian GNU/Linux testing/unstable dreamcast ttsc/1
  dreamcast login : root
  
  Linux dreamcast 2.4.5 #27 Thu May 31 07:06:51 JST 2001 sh4 unknown
  Most of the programs included with the Debian GNU/Linux system are
  
  freely redistributable ; the exact distribution terms for each program
  
  are described in the individual files in /usr/share/doc/*/copyright
  Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
  
  permitted by applicable law.
  dreamcast : # uname -a
  
  Linux dreamcast 2.4.5 #27 Thu May 31 07:06:51 JST 2001 sh4 unknown
  dreamcast : # cat /proc/cpuinfo 
  
  cpu family : SH-4
  
  cache size : 8K-byte/16K-byte
  
  bogomips : 199.47
  Machine : dreamcast
  
  CPU clock : 200.00MHz
  
  Bus clock : 100.00MHz
  
  Peripheral module clock : 50.00MHz
  dreamcast : # top -b
   09:14:54 up 14 min,  1 user,  load average : 0.04, 0.03, 0.03
  
  15 processes : 14 sleeping, 1 running, 0 zombie, 0 stopped
  
  CPU states :   1.1% user,   5.8% system,   0.0% nice,  93.1% idle
  
  Mem :     14616K total,    11316K used,     3300K free,     2296K buffers
  
  Swap :        0K total,        0K used,        0K free,     5556K cached
    PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
  
    219 root      18   0  1072 1068   868 R     5.6  7.3   0:00 top
  
      1 root       9   0   596  596   512 S     0.0  4.0   0:01 init
  
      2 root       9   0     0    0     0 SW    0.0  0.0   0:00 keventd
  
      3 root       9   0     0    0     0 SW    0.0  0.0   0:00 kswapd
  
      4 root       9   0     0    0     0 SW    0.0  0.0   0:00 kreclaimd
  
      5 root       9   0     0    0     0 SW    0.0  0.0   0:00 bdflush
  
      6 root       9   0     0    0     0 SW    0.0  0.0   0:00 kupdated
  
      7 root       9   0     0    0     0 SW    0.0  0.0   0:00 kmapled
  
     39 root       9   0   900  900   668 S     0.0  6.1   0:00 devfsd
  
     91 root       8   0   652  652   556 S     0.0  4.4   0:00 pump
  
     96 daemon     9   0   524  524   420 S     0.0  3.5   0:00 portmap
  
    149 root       9   0   944  944   796 S     0.0  6.4   0:00 syslogd
  
    152 root       9   0   604  604   456 S     0.0  4.1   0:00 klogd
  
    187 root       9   0   540  540   456 S     0.0  3.6   0:00 getty
  
    201 root       9   0  1380 1376  1112 S     0.0  9.4   0:01 bash
  

  Note that at this point I had shutdown both gpm and inetd. The rest of the processes, save for bash, are default. The above stats only report about 14 MB of RAM ; where are the other 2 MB ?

  dreamcast : # df -h
  Filesystem            Size  Used Avail Use% Mounted on
  /dev/rd/1             2.0M  560k  1.4M  28% /
  

• VP8 for Real-time Video Applications

  15 février 2011, par noreply@blogger.com (John Luther)

  With the growing interest in videoconferencing on the web platform, it’s a good time to explore the features of VP8 that make it an exceptionally good codec for real-time applications like videoconferencing.

  VP8 Design History & Features

  Real-time applications were a primary use case when VP8 was designed. The VP8 encoder has features specifically engineered to overcome the challenges inherent in compressing and transmitting real-time video data.
  

  • Processor-adaptive encoding. 16 encoder complexity levels automatically (or manually) adjust encoder features such as motion search strategy, quantizer optimizations, and loop filtering strength.
  • Encoder can be configured to use a target percentage of the host CPU.
    Ability to measure the time taken to encode each frame and adjust encoder complexity dynamically to keep the encoding time per frame constant
  • Robust error recovery (packet retransmission, forward error correction, recovery frame/new keyframe requests)
  • Temporal scalability (i.e., a single video bitstream that can degrade as needed depending on a participant’s available bandwidth)
  • Highly efficient decoding performance on low-power devices. Conventional video technology has grown to a state of complexity where dedicated hardware chips are needed to make it work well. With VP8, software-based solutions have proven to meet customer needs without requiring specialized hardware.

  For a more information about real-time video features in VP8, see the slide presentation by WebM Project engineer Paul Wilkins (PDF file).

  Commercially Available Products

  Millions of people around the world have been using VP7/8 for video chat for years. VP8 is deployed in some of today’s most popular consumer videoconferencing applications, including Skype (group video calling), Sightspeed, ooVoo and Logitech Vid. All of these vendors are active WebM project supporters. VP8’s predecessor, VP7, has been used in Skype video calling since 2005 and is supported in the new Skype app for iPhone. Other real-time VP8 implementations are coming soon, including ooVoo, and VP8 will play a leading role in Google’s plans for real-time applications on the web platform.

  Real-time applications will be extremely important as the web platform matures. The WebM community has made significant improvements in VP8 for real-time use cases since our launch and will continue to do so in the future.

  John Luther is Product Manager of the WebM Project.