Saturday, October 26, 2013

Convert M4V to AVI Using ffmpeg

I tried numerous ffmpeg settings to convert some M4V (MP4) files into AVI. Most either didn't work or crashed with a segmentation fault.

The only one I found that worked was this answer at StackOverflow. However, the quality of the file produced using the settings in the answer wasn't great, so this is what I ended up using:

ffmpeg -i input.m4v -f avi -b 2048k -ab 160k -ar 44100 output.avi

The output files are about twice the size of the input file, unfortunately, but they look decent.

Sunday, October 20, 2013

AMD GPU on Linux, Revisited

It's been almost a year since I first tried to run an AMD graphics card on Linux. After some success with an AMD A-CPU build a few weeks back, I picked up a 2nd hand HD7770 yesterday to try out and see if things have improved.

There were a number of tests I was interested in doing. I didn't have a convenient dual-monitor setup available, so everything is on a single screen (dual screen was one of my major problems last time, so I might get around to this at some point). The tests were:

  • Dragging a window around, looking for tearing
  • Scrolling in a web browser, looking for tearing again
  • Playing a HD video
  • Playing a game

I installed the card on my old Intel Q6600 system, and ran off the onboard graphics to start with, to get a baseline. I installed a fresh Kubuntu 13.04 as the test platform. These are the results, discussion at the end:

Test 1: Intel i915 (onboard) Graphics
Drag windowXNoticeable glitches
Browser scrollXOccasional glitches
GameXUnplayable (took a few minutes and hadn't even made it through the intro to the title screen)

Test 2: Open Source (Radeon) Drivers
Drag windowXNoticeable glitches
Browser scrollXOccasional glitches, similar in appearance to the onboard performance
GameXGame ran, going from 20 FPS sometimes down to 5. Some major glitching, and eventually a black screen. Not playable.

Example of the in-game glitching with the open source drivers

Test 3: AMD Catalyst 13.4
Drag window:)Looks nice, but need to ensure "Tear Free" option is selected in AMD Control Centre
Browser scroll:)Again, need to ensure "Tear Free" option is selected
Movie:)And again
Game:DVery good results (eventually), no noticeable lag on full-screen.

I intended to use 13.10, but the current version of Catalyst wouldn't install properly, so I dropped back to 13.04.

Installing the driver is still fraught with difficulties. The first couple of attempts failed -- even using the ubuntu libraries with apt-get install fglrx fglrx-amdccle wouldn't work. In the end, the way I got it going was by following the instructions in this askubuntu answer. In particular, I think getting all the dependencies is critical.

The proprietary driver may have an unfair advantage in my tests drag/scroll tests, since I found the "Tear Free" switch. I'm not sure if such an option exists for the open source drivers.

So, I had better luck than last time round, but the installation process is still daunting, and dual-screen support would be good to try out.

Thursday, October 17, 2013

Fixing KDE Games Menu Crash

After installing the game "A Virus Named Tom" from the Humble Bundle 9, trying to view the "Games" menu in KDE started crashing.

The problem is due to the file avirusnamedtom_com-avirusnamedtom_1.desktop in ~/.local/share/applications. It contains a reference to an image where either a) the reference is invalid because it contains spaces, or b) the image is unreadable.

To fix the problem, I edited the Icon line from:

  VirusNamedTom/A Virus Named TOM.bmp


  VirusNamedTom/A Virus Named TOM.bmp"

(Line break above is for clarity -- there is no line break in the file).

After logging out and logging back in, the Games menu should work again (although the icon for AVNT still doesn't appear properly, and I can't open the file in the default image viewer, which makes me think it's broken in some way. GIMP can open it without any problem, so I'm not sure what the issue is).

An alternative solution is to rename or delete the .desktop file, but then you lose the AVNT menu entry.

Also note this should fix a crash when clicking on the menu and selecting "Edit Applications..." -- which also occurred until I made this fix.

Hat tip to abelthorne, who posted the clue that led me to track this down.

Update 17/10/2013:
After a bit more experimentation, I found that the image can be made to work in the Games menu by saving as it as .PNG in GIMP, removing the spaces in the filename, and removing the quotes in the Icon entry in the .desktop file. There are some weirdnesses or limitations in the .desktop format it seems, and also something strange with the .BMP that comes with AVNT.