[CALUG] MPEG / DVD Tools

[Craig Younkins]

I have some experience encoding video, although not on linux. I have a few
tidbits to add:

* Try out multiple compression settings for a small, designated length of
video. Keep it to maybe 1-2 mins long with some action. Make a table and
note the settings, resultant file size, and the time it took to transcode
it.

* Keep in mind video and audio are separate encodings.

* If you are encoding to burn to a DVD to play on a DVD player, you need to
conform to DVD standards. Double check, but I believe this means MPEG2 video
and MP3/AAC/AC-3 audio.

* If you are encoding to watch on a PC, you can achieve much higher
compression rates using one of the best codecs available: x264. x264 is a
FOSS encoder for H.264/MPEG4-AVC. I know the number of acronyms in this
email may get newbies confused, but don't worry too much. x264 is very very
good, although it may take a while to encode. You can play it with a good
player like mplayer or VLC.

* Know and understand the following things:
constant bit rate (CBR)
variable bit rate (VBR)
average bit rate (ABR)
two-pass encoding
codec vs container

* Know what approximate bitrate you need. If you want 60 mins of video to
come out to be 4.6 GB (0.1 GB buffer).....
4.6 GB = 37683.2 megabits
60 min = 3600 sec
megabits/sec = 10.4675556 Mbps (megabits per second) for video AND audio.
Check my math. I had surgery last week and am still on painkillers.

* Dave is right: Getting the right compression settings is practically an
art form, and difficult to perfect. *Run tests* Run tests so you don't end
up with crappy video after 12 hours of encoding, and so you don't end up
with a filesize 100 MB too big.

I hope this helped! Feel free to ask more specific questions. I can't tell
you about the settings on ffmpeg though. You might also look at
*mencoder*as an alternative to ffmpeg. Good luck!!!

Helpful links:

http://www.doom9.org/
http://www.videolan.org/developers/x264.html
http://en.wikipedia.org
http://www.mplayerhq.hu/design7/news.html

Craig Younkins

On Sun, Jul 27, 2008 at 8:36 AM, Dave Dodge <dododge at dododge.net> wrote:

> On Sun, Jul 27, 2008 at 07:47:25AM -0400, Rajiv Gunja wrote:
> > I would like to know if there is a batch processing software which
> > can export these .DV files to mpeg or anything that is high quality
> > and a manageable size (DVD R5).
>
> For batch-mode file conversions, see:
>
>  mjpegtools
>  http://mjpeg.sourceforge.net/
>
>  ffmpeg
>  http://ffmpeg.mplayerhq.hu/
>
> > Also after converting, it seems to be of much lower quality than the
> > raw .DV file.
>
> Most likely due to the compression settings.  I suspect getting really
> good results while significantly dropping the bitrate is something of
> an art form.  It may take lots of test runs to figure out which
> settings and processing steps work best for your video content.
>
>                                                  -Dave Dodge
>
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