[PD] Re: [GEM-dev] Codecs in Gem (again!) & ffmpeg

B. Bogart ben at ekran.org
Wed Aug 31 05:05:25 CEST 2005

Thanks for the suggestions.

I'm not sure about using a mpeg for the following reasons:

#1. was does the interframe compression thing work, in other words how
does it compare when seeking to a quicktime with photo-jpg codec?

#2. I'm damn confused about the seeking (see below)

So I have mpeg1 and mpeg3 on my machine,

% "open alea.mpg 4" gives me a seekable file.
GEM: pix_film: Loaded file:
/home/bbogart/pd-stuff/Gem/examples/data/alea.mpg with 31 frames (320x240)
% file alea.mpg
alea.mpg: MPEG sequence, v1, progressive Y'CbCr 4:2:0 video, 320x240,
4:3, 30 fps

% "open test.mpg 4" gives me a unseekable file.
GEM: pix_film: Loaded file: /raid0/membrane/test.mpg with 0 frames (640x480)
% file test.mpg
test.mpg: MPEG sequence, v1, system multiplex

test.mpg was created with ffmpeg.

So if an mpeg performs as well as a quicktime with photo-jpeg than can
someone give me an example of how to create an mov that will be seekable
in Gem using mjpegtools or transcode? Since obviously its not difficult
to make an unseekable one...

Aside: What id the different between mjpeg and photojpeg as a video
codec? ffmpeg reports my sequence of jpegs as "mjpeg"...

Ok, I'm installing mjpegtools and netpbm.


IOhannes m zmoelnig wrote:
> B. Bogart wrote:
>> Hello all, sorry for the cross-posting,
>> So my final questions are:
>> 1. What codec should I use for 300,000 frames (14GB or so) and is well
>> suited to build from jpg frames? What container?
> as marc has pointed out: mjpegtools
> you can also use ppmtompeg (on debian this is part of netpbm) to create
> an mpeg out of a series of images (despite of the "ppm" in the name they
> can also be jpegs)

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