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writing a new proxy encode script - patent free.

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Sun, 09/02/2012 - 23:11
#1
gingerling
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Joined: 07/10/2012
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writing a new proxy encode script - patent free.

Hi,

I would like to use ogg/theora etc for my proxies, however, currently I have only one option which is an mpeg.

As discussed here http://www.kdenlive.org/forum/finding-best-profile-proxy-encoding there are some problems with this.

Can someone help me to write a new script to allow for non-patended proxies? This is really the last piece of my free software video workflow manual, but totally beyonde my current skills to write.

So far I tried just pasting the theora render script into the make new proxy script editor thing, but that didnt work. I tried to research how to write one from scratch but found very little info.

Best

Anna

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Mon, 09/03/2012 - 20:13
#2
TiKaey
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Joined: 05/24/2008
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Re: writing a new proxy encode script - patent free.

I've just play with it...
You may try this one:

-f ogg -acodec libvorbis -ab 128k -ar 48000 -vcodec libtheora -vb 2000 -deinterlace -s 480x270 -vb 400k

File extension: ogv

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Tue, 09/04/2012 - 10:07
#3
gingerling
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Re: writing a new proxy encode script - patent free.

hum, well its doing something - but taking a long long time to create the proxies. The file video I am editing is lossless and very large, however, the mpeg proxy encode is quite quick. How would I work on speeding this up? It looks quite similar "numerically" to the mpeg one, so can't guess what the difference is.

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Tue, 09/04/2012 - 10:39
#4
TiKaey
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Re: writing a new proxy encode script - patent free.

try another options ... another bitrate or so. Play with it.
That options i've used are only copied from mpeg-options. :o)

I don't try it for long, just for this posting. Maybe it need more time for encoding ogv than mpeg. Don't know.
Maybe "man ffmpeg" show you options, you want to use.

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Tue, 09/04/2012 - 16:57
#5
Marko
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Joined: 10/22/2009
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Re: writing a new proxy encode script - patent free.

Matroska is a free format. AFAIK MJPEG is not patent encumbered, and it is intraframe (I only), therefore fast to encode/decode and edit, so I suggest this:

-f matroska -acodec pcm_s16le -vcodec mjpeg -deinterlace -s 640x360 -vb 6000k

I call this proxy profile MJPEG6000 and the file extension is mkv

This gives cca 5x smaller files than SD DV, but the quality is good enough at least for the "story telling" part of the editing process, and probably for color adjustment too. For adjusting things like color key edges, sharpening and denoising, one should work with the original files anyway.
Another advantage of MJPEG is, that even the oldest FFMPEG, compiled without any extras, should be able to process it.

Audio is uncompressed and consumes cca 1/5 of the file size. I tried -acodec vorbis, but FFMPEG moaned something about it being experimental, so I did not use it, to reduce the probabilty of any problems - the price of less than 20% file size increase, to avoid both technical and legal patent problems, seems low enough to me. Especially since proxies are only temporary files, I think one should not loose time agonizing about audio codecs, and just use raw uncompressed audio.

For those working on a really weak hardware, maybe the "thumbnail sized" MJPEG3500 profile will work:

-f matroska -acodec pcm_s16le -ac 1 -ar 24000 -vcodec mjpeg -deinterlace -s 384x216 -vb 3500k

Audio is still uncompressed, but reduced to mono at half the sample rate, so it still consumes less than 20% of the output file.

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Wed, 09/05/2012 - 20:06
#6
gingerling
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Joined: 07/10/2012
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Re: writing a new proxy encode script - patent free.

hi, thanks - will try this one too! Have been having issues all day with proxies, not sure if it is the profile or not (TiKaeys one) - problems are thus

Playback from start of clip: struggles to get going, keeps stuttering out images from later on in the clip, a specific point, not the start, but always the same point. a little twiddling, rewind and start again etc, stops this.

Playback from new cut point: starts video fine, but audio is from a set point, usually earlier/the beginning of the clip, then skips ahead a few times till audio is in sync again. If I am trying to work with a clip of say 5 seconds, its impossible to do anything with, because the audio hasn't caught up by the time the video ends.

Does anyone think this could be down to the proxy settings directly? If I wasn't using proxies I would have assumed it was lack of ram causing issue indirectly, however isn't the point of proxies to avoid this?

Thanks for all the help, this is going to be fab when its all together :)

A
x

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Thu, 09/06/2012 - 10:32
#7
Marko
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Joined: 10/22/2009
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Re: writing a new proxy encode script - patent free.

I'm not very familiar with Kdenlive's inards, but I guess the editing engine shouldn't even be avare whether it's working with "originals" or "proxies"?

Try editing some "original" files of smaller resolution. The "supported camcorders" part of these pages is a good source of test videos.

I suggest you try the DV (SD) format (works very well on my setup), first without and then with proxies, to see where the problem lies.

NOTE: To get proxies from SD videos, you will have to set the "convert videos bigger than..." in the project/proxy setings window to 600 or so (less than the width of your source material, which is 720 for DV).

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Fri, 09/07/2012 - 11:37
#8
gingerling
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Re: writing a new proxy encode script - patent free.

hi, marko's encode profile solved the problem, so it must have been an issue with the first profile I tried - things have been working fine since, excepting a bug with transitions between parts of the same clip :S

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