LWN: Comments on "Transmageddon and Arista pursue simple transcoding"

Scale while transcoding?

bmur — Thu, 11 Jun 2009 09:44:54 +0000

The "commands" link the article hits close to home for me.

I need to take screen capture videos from projector screen size (AVI 1024x768) down to something that will work on a standard def DVD (h.264 640x480??).

If it were a photo, I would scale it with gimp and get some nice interpolation so that the picture doesn't go blurry.

Will either of these programs help me get my lecture video captures into a television sized format so that I can drop it into a video editor for voice-over?

In the past I tried pointing a video camera at the projection screen and the end result didn't look too good. I'm hoping capturing it at the source (in the computer) will yield better results.

Transmageddon and Arista pursue simple transcoding

hozelda — Mon, 08 Jun 2009 15:34:07 +0000

I haven't used dbus very much, but I get the impression it's just another means to expose interfaces except that you will have a daemon running ready to answer the call. The main benefit I see here is that you might keep certain initialized context in memory (if the calls are not spaced out too far apart in time) instead of saved to disk as any cli interface tool could do to maintain state across calls. For some uses, having a way to keep info in memory across multiple process calls (avoiding read/write to disk and temp file management/cleanup) could provide a great reduction in latency.

I could be way off about what dbus provides. As usual, I'm always excited to be clued in and learn more about anything related to Linux.

Transmageddon and Arista pursue simple transcoding

debacle — Mon, 25 May 2009 16:29:18 +0000

I would like to see two features:

rotate/recode for videos from the photo camera
grab from DVD with selection of language(s) and subtitle(s)

(Btw. I built an Arista .deb for Debian sid, but I needed the "really-bad" gstreamer plugins from debian-multimedia.org. The "good, bad and ugly" from main are not enough.)

Transmageddon and Arista pursue simple transcoding

n8willis — Fri, 22 May 2009 19:04:29 +0000

As ssam already mentioned, Conduit has been discussed by the actual projects (don't have the link on hand right now, though) -- I can also think of other useful apps like Miro or Elisa that would benefit from having access to a transcoder. But, to answer the question, "just call Gstreamer" won't actually do anything; for you to perform the transcoding _using_ GStreamer you'll have to duplicate all of the steps that Arista abstracts; eliminating the need to do that is exactly the point.

Nate

Transmageddon and Arista pursue simple transcoding

Uraeus — Fri, 22 May 2009 08:38:09 +0000

@shredwheat
I am the author of Transmageddon, if you file a bug attaching a small video or explain what you need I could probably add it quickly. I assume what you need is a way to rotate the video around and we got a plugin called videoflip in GStreamer I can use for that.

Transmageddon and Arista pursue simple transcoding

pr1268 — Fri, 22 May 2009 05:19:14 +0000

Well, I was thinking more of the ./configure && make && make install variety of dependency issues (usually tripped when running the configure script). I use Slackware, and my preferred way of getting non-distro software is via source tarballs. But, thanks for your info!

Switches

eru — Fri, 22 May 2009 04:43:17 +0000

>...demand that every codec switch...

That is close to true about mencoder, but I have found ffmpeg usually does the right thing for common target formats with very few switches (mainly to set the bit rate).

...who regularly recycles a script...

me too, and that is the nice thing about a command-line tool: once you have tweaked the settings to your satisfaction, you can reuse it easily.

Transmageddon and Arista pursue simple transcoding

shredwheat — Fri, 22 May 2009 01:02:30 +0000

What I'm really looking for is a simple tool to clean up the videos I get from my digital camera. They are encoded with mjpeg which makes them mighty large compared to simple formats. Along with that I frequently need to reorient videos from my camera.

Just want something with an orientation switch and a "Go" button. Going to check out these two apps.

Transmageddon and Arista pursue simple transcoding

jimparis — Thu, 21 May 2009 19:07:40 +0000

I'm tempted to try out either of Transmageddon or Arista, assuming I can wade through the dependency hell I'm facing

It always seems like video transcoding devolves into dependency hell -- not necessarily of the gnome/kde variety that you mention, but the fact that external tools and libraries are required to actually perform the transcoding. And these tools then get compiled with a variety of different options and enabled formats, so you can't just tell whether they will work from the version number. On one of my systems:

$ apt-cache policy ffmpeg
ffmpeg:
  Installed: 3:20080706-0.3lenny1
  Candidate: 3:20080706-0.3lenny1
  Version table:
     5:0.5+svn20090508-0.1 0
         80 http://www.debian-multimedia.org testing/main Packages
         50 http://www.debian-multimedia.org unstable/main Packages
     4:0.5+svn20090420-2 0
         50 http://debian.lcs.mit.edu unstable/main Packages
 *** 3:20080706-0.3lenny1 0
        990 http://www.debian-multimedia.org stable/main Packages
        100 /var/lib/dpkg/status
     3:0.svn20090303-1 0
         80 http://debian.lcs.mit.edu testing/main Packages
     0.svn20080206-17+lenny1 0
        990 http://security.debian.org stable/updates/main Packages
     0.svn20080206-17 0
        990 http://debian.lcs.mit.edu stable/main Packages

Now I understand that half the confusion here is from having the same package in debian-multimedia and Debian proper, but they're fundamentally different because the debian-multimedia one is often compiled against more non-free codecs.

I'd really, really love to see something like Arista as a standard package in Debian with properly vetted dependencies that make sure we're getting a known-good version of all the tools and libraries they use.

Transmageddon and Arista pursue simple transcoding

ssam — Thu, 21 May 2009 15:44:29 +0000

some possibilities:
* a youtube downloader could use it add an encode for your portable device button. then call Arista/Transmageddon with the path to the flv file.
* conduit, say you want to sync some videos between a folder on your hard disk, and a portable device. maybe conduit does not want to hold all the transcoding logic.

just wondering. for the device presets, will these programs query HAL/devicekit to ask what you currently have plugged in? i don't want to be hunting for my N800 in a huge list of PMPs, PDAs and whatever else.

subtitle support

alex — Thu, 21 May 2009 11:32:39 +0000

I've been using mencoder for a long time and I finally just fixed a script to encode for the one target I have (PS3). However I still haven't got a decent way of reliably generated synced subtitles. I have yet to find the one (or few!) clicks GUI to this nirvana.

Transmageddon and Arista pursue simple transcoding

pr1268 — Thu, 21 May 2009 01:03:36 +0000

I have an intuition that the D-Bus integration will be used for interfacing with tuner cards, video capture devices (IEEE-1394, etc.), Webcams, and similar.

Again, I'm going from intuition here, so I don't mind being corrected here if I'm wrong.

Transmageddon and Arista pursue simple transcoding

njs — Thu, 21 May 2009 00:42:57 +0000

Err, what is this D-Bus integration supposed to actually do, though? If I'm an app that just needs a video transcoded, surely I should just call gstreamer, rather than calling through D-Bus to a GUI wrapper around gstreamer...?

Transmageddon and Arista pursue simple transcoding

boerner — Thu, 21 May 2009 00:05:17 +0000

Very well done article. Does an excellent job of presenting the 'big picture', not just some posting about a new release of some app. More like this one please...

Transmageddon and Arista pursue simple transcoding

pr1268 — Wed, 20 May 2009 19:41:15 +0000

Command line encoders like FFmpeg and MEncoder can perform almost any conversion, but require the user to know exactly which options to enable, and, in most cases, demand that every codec switch be specified or else they fail to produce a usable result.

Don't I know it! (I'm a longtime MEncoder/MPlayer user who regularly recycles a script that contains a plethora of command-line switches whenever I'm transcoding video.)

Thanks for the article. I'm tempted to try out either of Transmageddon or Arista, assuming I can wade through the dependency hell I'm facing (I'm a KDE user and, if I understand correctly, these are GNOME/GTK apps).