Finding the best profile for proxy encoding

Dear all,

the current standard profile for proxy encoding seems to be not optimal in my eys – at least for ubuntu users: Encoding audio in mp3 is not enabled by default in a standard ubuntu installation, even if installed by sunab's ppa.

Therefor I would like to start a search for a better (or alternative) profile.
Who is willing to help me?

My first attempt would be to encode video to M-JPEG in an AVI container with PCM as audio:

-f avi -acodec pcm_s16le -ac 2 -ab 128k -ar 48000 -vcodec mjpeg -deinterlace -s 480x270 -vb 400k

What are your thoughts?

Regards

Jonathan Haug

mp3 is indeed patent encumbered, but why not using mp2 sound by using using twolame (libtwolame0), based on toolame, which is free and a standard component of Ubuntu.

I indeed promote the use of another audio codec as well but I would prefer mp2.

Yes, MP2 could do. I can't find any information that MP2 has any licence fees tied to it. Is it a compleatly free format? Given away to the public for free?
http://en.wikipedia.org/wiki/MPEG-1_Audio_Layer_II

Otherwise I'd say OGG Vorbis would be a good MP3 replacement! And OGG and Vorbis is free software.
http://en.wikipedia.org/wiki/Vorbis
http://en.wikipedia.org/wiki/Ogg

Hi, I would like an encode script for proxies which uses theora/ogg etc. Can someone help me write one?? I am createing a patent-free free-software video workflow and this is the very last missing link for me now x

Hi there.

Here's my next approach for a proxy profile:

-f matroska -vcodec mjpeg -qscale:v 15 -sn -vf scale=-1:288 -acodec pcm_s16le -ac 1

In detail:

-f matroska
-vcodec mjpeg
patent free container and codec, see discussion
http://www.kdenlive.org/forum/writing-new-proxy-encode-script-patent-free
mjpeg is an intraframe codec - > good for editing.
instead of mjpeg you could use any codec and add "-g 0" --> every frame will be a keyframe – as far as I do understand

-qscale:v 15
instead of setting a fixed bitrate I would prefer to set a specific quality (and a variable bitrate)
The range goes from 1 (best) to 31 (worst quality)
note: "qscale" (without ":v") is deprecated

-sn
disable subtitles
encoding proxies would keep chrashing for me without this, at least when using AVCHD/MTS clips from a Panasonic cam

-vf scale=-1:288
Instead of using "s= ..." I would prefer to use "scale=-1, ..." to keep the pixel aspect ratio.
288 pixel height seems enough for me, and it suits mod 16 = 0.
The next higher resolution would be "scale=-1:432"

-acodec pcm_s16le
-ac 1
uncompressed audio, mono
note: no "-ab" --> leaving audio bitrate unchanged to avoid issues with audio sync

Additionally you could use the videofilter "yadif" to deinterlace, but be sure to add it before(!) the scale filter:
-vf yadif,scale=-1:288
(Note: "-deinterlace" is deprecated in ffmpeg/avconv)

What are your thoughts?

Greetings

Jonathan

Hi all,

could some of you give the above proxy profile a try?
I would like to file a bug to propose this profile (or a better one ...) as default in kdenlive and it would be great to have some more tests before.

Thanks in advance

Jonathan

Will try it when i'm back at home next week.

Edit: Tried out. So far it worked, but for me the image-quality is to bad. Because when i'm editing clips, i want to see more specific, how it changes with effects or so. So "qscale" must be '1' to use it for a good looking material.

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