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Since I'm planning to finish my encoding tests that Ralph asked me to
do a while ago after I return to the US (God-willing!), I thought I'd
throw out a request to other more-experienced video folks. Please
recommend to me any good sources (freely and/or legally available)
that I can use for my testing of the encode/decode speeds as well as
quality comparisons between libtheora 1.0 and the latest SVN trunk at
the time of testing.
The kinds of sources I have available of my own include the following:
1. Lots of videos of varying quality produced by my Canon PowerShot
A550 camera. These are all in MJPEG format, VGA (640x480)
resolution, and have 30 frames per second. Despite the high
bitrate (sometimes approaching 40kb/s) of some of these videos
(with the help of CHDK), they quality is quite low, as MJPEG is
a very inefficient intra-only encoding format. Still, I think
this is a typical end-user case of video encoding, and would be
in the class of videos people might upload to video sharing
sites like *tube's.
2. Lots of videos I create from series of time-lapse iequences I've
taken myself. These originate from high-resolution (3072x2304)
stills which I resample and/or crop to more useful sizes
(640x480, 1280x720, and 1920x1080). I tend to make the
sequences run at 15, 24, or 30 frames per second. I still have
all these stills, so I can make almost any type of video from
these sequences. The results tend to be the highest-quality
amongst the videos I am capable of creating myself.
Recommendations are welcome. ;)
3. DVD video files from the Planet Earth series (from my own set).
These are reasonably high quality and I think they would be good
representation of a typical transcoding usage case for Theora.
They will have to be deinterlaced first, though, as Theora does
not support interlacing, right? I don't own many other DVDs, as
I tend to not watch movies.
4. Some computer generated videos that can be created from Fyre and
other free software tools. These tend to be very high quality
but of limited complexity and/or scope. For example, the images
produced by Fyre are usually limited to a single color or range
of colors in abstract shapes & arrangement.
5. Miscellaneous videos downloadable via the web. These can
include anything from game trailers to the fascinating
CC-licensed Dimensions series. Naturally, these are all already
compressed using various codecs (MPEG-4 ASP, WMV3, H.264/AVC,
etc.), so they would be tests of transcoding rather than
absolute quality. Still, that is yet another usage case that is
important, especially in the realm of a free-as-in-freedom video
sharing website, such as theorasea.org and whatnot.
6. NTSC-DV clips. My father owns a DV (technically Digital8)
camcorder and I've taken one set of videos and captured another
that my father recorded. The quality tends to be good, but not
great. Also, the video is interlaced. Finally, the pixel
format is 4:1:1 planar, which means we have to go from one lossy
colorspace to another. But, this is yet another case that many
people might do (albeit to less and less degrees as time passes,
as the DV standard is fading from common usage).
So, with that in mind, I would like to augment what I have above (I
may choose not to use some of them for whatever reasons) with what
others with more experience than me might recommend. I know there are
some common defacto standard clips that tend to pop-up from
time-to-time in codec-related postings and/or articles, such as the
clip of the foreman on the construction site. However, I have not
found these clips anywhere. I'm not sure if it's all that important,
but I thought a familiar reference might be useful for absolute
comparisons.
Anyway, that's about it. I'll be continuing to prepare for our move
from Malaysia back to the US over the next couple of days, but I am
looking forward to doing more comparisons and tests after my arrival,
especially as I'll have a full desktop available to me rather than my
aging 4-year-old+ laptop.
Thanks!
- --
Basil Mohamed Gohar
abu_hurayrah at hidayahonline.org
http://www.basilgohar.com/blog
basilgohar on irc.freenode.net
GPG Key Fingerprint: 5AF4B362
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