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| Codec overview http://forum.linhes.org/viewtopic.php?f=17&t=13841 |
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| Author: | myth@chakobsa.net [ Thu Jan 25, 2007 8:43 pm ] |
| Post subject: | Codec overview |
Does anybody here have a good clear understanding of all about codecs and the ability to write a general intro/overview? I couldn't find anything like that in searching the forum and the wiki. I've got Linux, Windows, and OS X machines at home so I'm very concerned about portability and platform independence. I've had very hit or miss results in moving video files back and forth between Knoppmyth and the other machines. Sometimes no video, sometimes no audio, sometimes the file won't play at all. What tools are available to analyze video files to determine what software is required to play it? How can I determine what codecs a Linux, Windows, or OS X box can play? I think we need a good primer on this subject. |
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| Author: | marc.aronson [ Thu Feb 01, 2007 9:28 am ] |
| Post subject: | |
There is a lot published on the web about various codecs. The very first intro I read was called "Codec central" -- http://www.siggraph.org/education/mater ... efault.htm. You may also find this useful - http://www.videolan.org/vlc/features.html There are many other pages if you google around. A common cause for not being able to play a video file on a machine is that that the requried codec isn't install. One of the better multi-platform players is VLC -- you can find it at www.videolan.org. The nice thing about this player is that it comes bundled with a wide range of codecs. My experience is with Linux and Windows -- can't comment about OS X as I don't use it: 1. mpeg2 records in a program sream ("PS") contains are very portable. 2. A year ago I was having quite a few problems with mpeg2 recordings in a transport stream ("TS") container, but these days the new versions of the players seem to handle them well. 3. xvid in an AVI contains seems to work well on both windows & Linux. Good luck! Marc |
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| Author: | psicard [ Thu Feb 01, 2007 1:49 pm ] |
| Post subject: | |
Quote: What tools are available to analyze video files to determine what software is required to play it?
You can use GSpot on Windows to determine what codec you need to have installed to play a video file http://www.headbands.com/gspot/ If you have problems, it's not probably software per se that you need to install, but the proper codecs. Usually any video player can access any of the codecs you have installed. Uncompressed video files are HUGE and unwieldy. So, all video files use some sort of compression to get the file size down. The compression methodology is called a codec (COmpressor/DECompressor). Codecs vary wildly in their efficiency (how small the compressed file is), quality (artifacts, black levels, color reproduction, etc.) and ownership (proprietary, open source, open standard). Once the file is compressed, you need to store information about the file (what codec, etc.) somehow. This is where the difference between a WMV, AVI and Quicktime (MOV) comes in. Each of these file formats has different rules about how to store this additional info. So, what does this mean in a practical sense? Well, if you were to set MythTV to automatically transcode your recordings to something like an xvid avi, install the xvid codec on all of your various platforms, then you should have no portability problems (though you may have to install Windows Media Player on the Mac if it can't handle an avi). |
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