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• FFMPEG - Moving text to appear every 'X' Seconds

  23 septembre 2015, par Kevin

  This is a ffmpeg command for moving text (left to right)

  ffmpeg -i input.mp4 -vf drawtext="fontfile=/path/to/fonts/FreeSans.ttf:text='Hello World':fontcolor=white@1.0:fontsize=16:y=h-line_h-100:x=(2*n)-tw" -codec:v libx264 -codec:a copy output.mp4

  And I would like to know how to make the moving text to start after ’X’ seconds and appear every ’X’ seconds ?

• PC Video Conferencing in the Year 1999

  21 juin 2011, par Multimedia Mike — General

  Remember Intel’s custom flavor of H.263 cleverly named I.263 ? I think I have finally found an application that used it thanks to a recent thrift shop raid— Intel Video Phone :

  
  
  

  The root directory of the disc has 2 copies of an intro.avi video. One copy uses Intel Indeo 3 video and PCM audio. The other uses I.263 video and an undetermined (presumably Intel-proprietary) audio codec — RIFF id 0x0402 at a bitrate of 88 kbits/sec for stereo, 22 kHz audio. The latter video looks awful but is significantly smaller (like 4 MB vs. 25 MB).

  This is the disc marked as "Send it to a friend...". Here’s the way this concept was supposed to operate :

  • You buy an Intel Video Phone Camera Pack (forgotten page courtesy of the Internet Archive) which includes a camera and 2 CDs.
  • You install the camera and video phone software on your computer.
  • You send the other CD to the person whom you want to be able to see your face when you’re teleconferencing with them.
  • The other party installs the software.
  • The 2 of you may make an internet phone call presumably using commodity PC microphones for the voice component ; the person who doesn’t have a camera is able to see the person who does have a camera.
  • In a cunning viral/network marketing strategy, Intel encourages the other party to buy the physical hardware as well so that they may broadcast their own visage back to the other person.

  If you need further explanation, the intro lady does a great job :

  
  
  

  I suspect I.263 was the video codec driving this since Indeo 3 would probably be inappropriate for real time video applications due to its vector quantizing algorithm.

• Dreamcast Archival

  24 mai 2011, par Multimedia Mike — Sega Dreamcast

  Console homebrew communities have always had a precarious relationship with console pirates. The same knowledge and skills useful for creating homebrew programs can usually be parlayed into ripping games and cajoling a console into honoring ripped copies. For this reason, the Dreamcast homebrew community tried hard to distance itself from pirates, rippers, and other unsavory characters.

  
  
  

  Funny how times change. While I toed the same line while I was marginally a part of the community back in the day, now I think I’m performing a service for video game archivists and historians by openly publishing the same information. I know of at least one solution already. But I think it’s possible to do much better.

  Pre-existing Art
  Famed Japanese game hacker BERO (FFmpeg contributors should recognize his name from a number of Dreamcast-related multimedia contributions including CRI ADX and SH-4 optimizations) crafted a program called dreamrip based on KOS’s precursor called libdream. This is the program I used to extract 4XM multimedia files from Alone in the Dark : The New Nightmare.

  Fun facts : The Sega Dreamcast used special optical discs called GD-ROMs. The GD stands for ‘GigaDisc’ which implied that they could hold roughly a gigabyte of data. How long do you think it takes to transfer that much data over a serial cable operating at 115,200 bits/second (on the order of 11 Kbytes/sec) ? I seem to recall entire discs requiring on the order of 27-28 hours to archive.

  If only I possessed some expertise in data compression which might expedite this process.

  KallistiOS’ Unwitting Help
  The KallistiOS (KOS) console-oriented RTOS provides all the software infrastructure necessary for archiving (that’s what we’ll call it in this post) Dreamcast games. KOS exposes the optical disc’s filesystem via the /cd mount point on the VFS. From there, KOS provides functions for communicating with a host computer via ethernet (broadband adapter) or serial line (DC coder’s cable). To this end, KOS exposes another mount point on the VFS named /pc which allows direct access to the host PC’s filesystem.

  Thus, it’s pretty straightforward to use KOS to access the files (or raw sectors) of the Dreamcast disc and then send them over the communication line to the host PC. Simple.

  Compressing Before Transfer
  Right away, I wonder about compiling 3 different compression libraries : libz, libbz2, and liblzma. The latter 2 are exceptionally CPU-intensive to compress. Then again, it doesn’t really matter how long the compressor takes to do its job as long as it can average better than 11 Kbytes/sec on a 200MHz Hitachi SH-4 CPU. KOS can be set up in a preemptive threading mode which means it should be possible to read sectors and compress them while keeping the UART operating at full tilt.

  A 4th compression algorithm should be in play here as well : FLAC. Since some of these discs contain red book CD audio tracks that need archival, lossless audio compression should be useful.

  This post serves as a rough overview for possible future experiments. Readers might have further brainstorms.