Archive for the ‘mac’ Category

Solving Snow Leopard Crashes on a 24″ iMac

February 3, 2011

My 24″ iMac (early 2008, Core2 Duo 2.8GHz) came with MacOS 10.5 Leopard and worked great with it. When 10.6 Snow Leopard came out, I upgraded to it, and thereafter the iMac started crashing 1-3 times a week. The screen would turn black, or gray, or striped. It wasn’t totally dead, which would suggest a power supply failure. It wasn’t a kernel panic (with the multi-lingual “You need to restart your computer” message), which would suggest bad RAM. But it was hung and couldn’t be reached over the network. To recover, I had to hold down the power switch to force a shutdown, then turn it back on.

It happened sometimes while the machine was idling, other times while I was in the middle of doing something. This persisted through the 10.6.4 update, at which point I decided MacOS updates weren’t going to fix it.

I tried a clean install of Snow Leopard, but that didn’t fix it. I replaced the RAM with a different brand, but that didn’t fix it. I had the main logic board replaced under AppleCare, but that didn’t fix it. After some searching of the web, I found the solution. It confirmed my hunch that the video chip was overheating. The video chip (GPU) in mine is an ATI Radeon HD 2600 Pro. Apparently Snow Leopard drives the GPU harder than Leopard does, but runs the iMac’s fans at the same barely-audible speeds. The problem is more likely to occur on iMacs that are left on all the time, as mine is.

The solution is to install a third-party fan control program to force the fans to run faster and keep the inside of the Mac cooler. I installed iMac Fan Control. The iMac’s fans are now audible, but not too objectionable, and it hasn’t crashed in the two months or so since I installed iMac Fan Control. The temperatures are significantly lower than before. Here is a picture of my iMac Fan Control System Preferences panel.

Update: A year after installing iMac Fan Control, the iMac hasn’t crashed even once from the video chip problem. It’s currently running MacOS 10.6.7 plus the Snow Leopard Font Update.

Making DVD File Systems

December 30, 2010

If you have a VIDEO_TS folder, which is the files to make a video DVD, and you’re using a Mac, how can you create a playable DVD? There are a couple of free programs I like for this.

Both iDVD and DVD Studio Pro, among other programs, can create video DVD title set files (VIDEO_TS folders), but those need to be burned to DVD in a special format (called UDF 1.02). To make a playable video DVD, you can burn a VIDEO_TS folder to DVD using the program LiquidCD. Or you can create an ISO image file with the program AquaISO. Later you can burn the ISO file to a DVD using LiquidCD, Disk Utility, SimplyBurns, or other programs (including a bunch on Windows).

Why would you want to save a VIDEO_TS folder or ISO file on a hard drive instead of burning a DVD directly from iDVD or DVD Studio Pro? Several reasons. It’s a convenient way to burn multiple copies. It’s a way to keep an archive copy in a compact format. You might need to copy or send it to other people so they can burn it to DVD. You might need to make changes to the files before burning them to DVD, using a program such as MyDVDEdit (such as to work around iDVD bugs in handling 16:9 videos). You might have created the VIDEO_TS folder using some other software or gotten it from someone else. You might want more control over the burning process, such as burning at a lower speed for higher quality (DVD Studio Pro doesn’t let you control the burning speed).

From Flash to MP4

May 25, 2010

I’ve been thinking about saving some Flash videos from YouTube, Vimeo (videos without a download link), and other sites for playing on iPods and other platforms that don’t support Flash video. Since most Flash video these days uses the h.264 codec, it should be possible to de-multiplex the .flv file to extract the video and audio streams, then re-multiplex them into an MP4 container, with no re-encoding.

On a Mac with Perian and QuickTime Pro installed, just open the .flv file in QuickTime Player 7, do “Save As,” choose “self-contained movie,” and after a few seconds, you’ll get a copy of the video in a QuickTime .mov file.

There’s also a more roundabout way to do it on Windows, if you really want a .mp4 container file.

  1. Download the Flash video file (.flv extension). The Firefox add-on DownloadHelper is one way to do this. You should probably download the highest-resolution version available.
  2. Run FLV Extract and drop the .flv file onto it to create .264 and .aac files, which contain the video and audio respectively. If it produces files with different extensions, your Flash video file isn’t encoded in h.264 so the next step won’t work, sorry.
  3. Run YAMB and add the .264 and .aac files to re-multiplex them into a .mp4 file.
  4. Play the .mp4 file and check that audio and video stay in sync before you delete the .flv file.

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