Hi Friends,
For those interested in streaming of digital videos and music, here is a description of some of the frequently used terms. I quote this from a Videolan Document, although the description is general (BTW VLC was originally Videolan Client and VLS the Videolan Server. Now VLC combines both functions. MPEG is Motion Pictures Expert Group) :-
"What is a codec ?
To fully understand the VideoLAN solution, you must understand the
difference between a codec and a container format
* A codec is a compression algorithm, used to reduce the size of a
stream. There are audio codecs and video codecs. MPEG-1, MPEG-2,
MPEG-4, Vorbis, DivX, ... are codecs
* A container format contains one or several streams already encoded
by codecs. Very often, there is an audio stream and a video one.
AVI, Ogg, MOV, ASF, ... are container formats. The streams
contained can be encoded using different codecs. In a perfect
world, you could put any codec in any container format.
Unfortunately, there are some incompatibilities. You can find a
matrix of possible codecs and container formats on the
[13]features page
To decode a stream, VLC first demuxes it. This means that it reads the
container format and separates audio, video, and subtitles, if any.
Then, each of these are passed decoders that do the mathematical
processing to decompress the streams .
There is a particular thing about MPEG:
* MPEG is a codec. There are several versions of it, called MPEG-1,
MPEG-2, MPEG-4, ...
* MPEG is also a container format, sometimes refered to as MPEG
System. There are several types of MPEG: ES, PS, and TS
When you play an MPEG video from a DVD, for instance, the MPEG
stream is actually composed of several streams (called Elementary
Streams, ES): there is one stream for video, one for audio,
another for subtitles, and so on. These different streams are
mixed together into a single Program Stream (PS). So, the .VOB
files you can find in a DVD are actually MPEG-PS files. But this
PS format is not adapted for streaming video through a network or
by satellite, for instance. So, another format called Transport
Stream (TS) was designed for streaming MPEG videos through such
channels."
Finally, there are three procedures we are talking about in these threads. (1) How to watch tv programs on the pc. This is the simplest matter and there are good alternatives like webinterface, gemini tv, mgrab, mtuxvision etc. (2) How to record tv on the pc hard drive and playback on the pc monitor, on the tv or burn cd. The CIFS method seems to be the best for this. (3) The most problematic issue, how to playback dvd or files from the pc to the DB.
As Skydreamer says, the third method is only being looked at as a matter of finding out how to, since the simplest mehod is to use a dvd player or do what he says !
For anybody who wants to try the Vlc method follow Klona's guide for playing Divx, it will either work or not work depending on your computer and lan capacity. I have only managed by reducing video size, but still with occasional glitches.
Regards, pcd.
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