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• Play video files online sequentially without delay/buffering between videos

  26 février 2015, par Marko

  Is it possible to play video online that’s made of two or more video files ?

  Since my original post wasn’t clear enough, here’s expanded explanation and question.

  My site is hosted on Linux/Apache/PHP server. I have video files in FLV/F4V format. I can also convert them to other available formats if necessary. All videos have same aspect ratio and other parameters.

  What I want is to build (or use if exist) online video player that plays video composed of multiple video files concatenated together in real-time, i.e. when user clicks to see a video.

  For example, visitor comes to my site and sees video titled "Welcome" available to play. When he/she clicks to play that video, I take video files "Opening.f4v", "Welcome.f4v" and "Ending.f4v" and join/merge/concatenate them one after another to create one continuous video on the fly.

  Resulting video looks like one video, with no visual clues, lags or even smallest observable delay between video parts. Basically what is done is some form of on-the-fly editing or pre-editing, and user sees the result. This resulting video is not saved on the server, it’s just composed and played that way real-time.

  Also, if possible, user shouldn’t be made to wait for this merging to be over before he/she sees resulting video, but to be able to get first part of the video playing immediately, while merging is done simultaneously.

  Is this possible with flash/actionscript, ffmpeg, html5 or some other online technology ? I don’t need explanation how it’s possible, just a nod that it’s possible and some links to further investigate.

  Also, if one option is to use flash, what are alternatives for making this work when site is visited from iphone/ipad ?

• Dreamcast Track Sizes

  1er mars 2015, par Multimedia Mike — Sega Dreamcast

  I’ve been playing around with Sega Dreamcast discs lately. Not playing the games on the DC discs, of course, just studying their structure. To review, the Sega Dreamcast game console used special optical discs named GD-ROMs, where the GD stands for “gigadisc”. They are capable of holding about 1 gigabyte of data.

  You know what’s weird about these discs ? Each one manages to actually store a gigabyte of data. Each disc has a CD portion and a GD portion. The CD portion occupies the first 45000 sectors and can be read in any standard CD drive. This area is divided between a brief data track and a brief (usually) audio track.

  The GD region starts at sector 45000. Sometimes, it’s just one humongous data track that consumes the entire GD region. More often, however, the data track is split between the first track and the last track in the region and there are 1 or more audio tracks in between. But the weird thing is, the GD region is always full. I made a study of it (click for a larger, interactive graph) :

  
  
  

  Some discs put special data or audio bonuses in the CD region for players to discover. But every disc manages to fill out the GD region. I checked up on a lot of those audio tracks that divide the GD data and they’re legitimate music tracks. So what’s the motivation ? Why would the data track be split in 2 pieces like that ?

  I eventually realized that I probably answered this question in this blog post from 4 years ago. The read speed from the outside of an optical disc is higher than the inside of the same disc. When I inspect the outer data tracks of some of these discs, sure enough, there seem to be timing-sensitive multimedia FMV files living on the outer stretches.

  One day, I’ll write a utility to take apart the split ISO-9660 filesystem offset from a weird sector.

• Using Python script to cut long videos into chunks in FFMPEG

  23 février 2016, par Michael Hamilton

  Starting off by saying I’m not a programmer, but I really need the application this Python script I found says it can do.

  Auto-Splitting Script by Antarctic Nest of Icephoenix

  Basically I have a directory of long .MP4s that need to be cut into equal parts based on a total running time of 3 hours 15 minutes. For example, I would have an 8 hour video that needs to be cut into smaller parts each under 3:15:00.

  We’ve been manually crating FFMPEG codes to do this, but I found the Python script above that seems like it will do what we are needing. The issue is that I have no Python experience. I don’t know where in the script to enter in the folder path with the videos, or where to specify my codecs, or where to tell the program that the max time for each video chunk is 3:15:00.

  I’m on a 64-bit windows system working in command prompt

  Here’s what I have done :

  • Installed python 3
  • downloaded the script
  • I can click on the script to see the cmd window flash to indicate it’s running
  • I enter "C :\Python34\python.exe V :\ffmpeg\ffmpeg-split.py" into cmd

  • output is

    File "V :\ffmpeg\ffmpeg-split.py", line 16
    print "Split length can’t be 0"

      SyntaxError: Missing parentheses in call to 'print'

  I have no idea where to go from here. It seems like the script is loading properly, but I haven’t entered my variables. Any help with where to put the information would be appreciated.

  Here is the FFMPEG code we usually use :

  ffmpeg -i V :\ffmpeg\88518_63c392af.mp4 -vcodec libx264 -acodec copy -vf fps=fps=30000/1001 -ss 00:05:01.000 -t 02:43:49.000 V :\events\88518.mp4

  The ffmpeg codes we use :

  -i is a .mp4

  -vcodec h.264 codec

  -acodec should be “copy” or can be “libvo_aacenc”

  -vf fps=30000/1000 a forced fps of 29.97

  -ss is start time (we would use this to manually cut into parts along with -t)

  -t is duration (we would calculate the duration for each part as the total run time divided by the equal time under 3:15:00 be it two, three, or four parts)

  Thank you a million dollars