Gentoo Archives: gentoo-user

From: "Boyd Stephen Smith Jr." <bss03@××××××××××.net>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] ot - video encoding
Date: Sat, 24 Feb 2007 11:23:04
Message-Id: 200702240517.02818.bss03@volumehost.net
1 On Saturday 24 February 2007, Kellystewart00@×××××××××.au wrote
2 about '[gentoo-user] ot - video encoding':
3 > Hi List im looking for a program to encode from avi to divx does anyone
4 > know of a program to do this?
5
6 Short answer: mencoder
7
8 Longer answer:
9 (1) Avi is not a format -- or at least it's not a video format. It's
10 a "wrapper" format that can hold various video formats with various audio
11 formats interleaved. AVI = Audio/Video Interleave
12
13 (2) Mplayer and Xine are the big a/v decoders, with ffmpeg being used by
14 both projects (IIRC); vlc is a very useful third place, and gstreamer does
15 have some "native" codecs although it can (and IIRC, still generally does)
16 call out to the xine, mplayer, or ffmpeg libraries for some formats.
17
18 (3) Encoders are much more fragmented, although ffmpeg provides many
19 encoders, and mplayer can use the ffmpeg encoders as well as any native
20 ones it might have, plus it understands the libraries (or interfaces via
21 system() calls) with some others. Xine, vlc, and gstreamer are, AFAIK not
22 oriented towards encoding.
23
24 (4) Divx is just an video format and if you intend to combine it with
25 audio, you'll have to choose a format for that. I prefer vorbis; with
26 speex for those cases where is audio is literally just a voice-over.
27 However, vorbis and speex decoders generally aren't shipped with
28 proprietary OSes such as OS X or Windows and are playable on relatively
29 few portable devices. MP3 is fine for mono or stereo audio, but AFAIK it
30 doesn't support more channels. AC3 is IME larger for the same quality,
31 but does support 5.1 and other formats with more channels.
32
33 (5) Again, divx is just a video format, so you'll need a container format
34 if you want to combine it with other media, like subtitles or audio. I
35 prefer Matroska or ogg. Neither is shipped with proprietary OSes and both
36 have poor support on portables, although ogg has marginally better support
37 than Matroska. I don't believe divx is can be shipped in the standard mp4
38 container, but I could be wrong. It's normally shipped in, oddly enough
39 in your case, AVI format.
40
41 So, you have a couple more high-level decisions to make before you
42 transcode. Once you decide on them, you'll still need to determine
43 encoder-specific parameters, bitrates, and whotnot, although sane defaults
44 are generally provided by most tools when possible. However, the shear
45 number of options may be a little bit overwhelming. Tip: doesn't change
46 any settings you don't have to the first time, you can play with all
47 the "knobs" once you get base functionality.
48
49 Mencoder is probably is most featureful transcoding tool, but you may be
50 able to find a GUI that the features you need and is user-friendly. I
51 don't do enough transcoding to have any recommendations other than
52 mencoder, because I got familiar enough with it to do what I needed and
53 stopped looking for anything else.
54
55 --
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