GNU / Linux

Convert, Join, re encode AVCHD .MTS files in Ubuntu Linux

convert, encode and join avchd files in linux

One of our audio and video archive customers has a large collection of AVCHD video files that are stored in 1.9GB ‘chunks’ as xxxxx.MTS files. All these files are of 60 minute and longer duration and must be joined, deinterlaced, re encoded to a suitable size and bitrate then uploaded for online access.

This is quite a task in computer time and file handling. These small domestic cameras produce good HD movies for a low cost but the compression to achieve this is very high and does not give you a file that is easily edited. The .MTS files are MPEG transport stream containers for H264 encoded video.

There are some proprietary solutions for MacOS X and Windows that will repackage the .MTS files into .MOV Quicktime containers that can be accessed by MacOS X or re-encoded to a less compressed format for editing with Final Cut Pro or Premiere. We didn’t need this though, just a reliable and  quick open source workflow.

  1. The first and most important issue is to rejoin the camera split files.
    These cameras use FAT32 file systems which cannot handle individual files larger than 2GB so they split the .MTS video file into chunks. As each chunk in a continuous sequence references the other chunks these must be joined in the correct order. This is easily achieved with the cat command.
  2. The rejoined .MTS files can now be reencoded to a more manageable size using open source software such as Handbrake. We also needed to deinterlace our footage as it was shot interlaced and it would be accessed on progressive displays. This will increase the encoding time but without it any movement will look odd with visible artifacts.
  3. Finding the ‘sweet spot’ for encoding can be time consuming but in this case was important as projected text needed to be legible but the file sizes kept manageable for reasonable upload times!

 

Posted by greatbear in Video Tape, 0 comments

Focusrite Saffire LE SPDIF problems

Focusrite Saffire LE

Focusrite Saffire LE

I’ve owned one of these Saffire LE firewire interfaces for a few years now and it’s very useful as a backup to my RME interfaces especially when I need to record and transfer audio at another location as it’s small, light and portable. It’s a very good sounding interface and  it even is reported to work under Linux which I’ve tried but unfortunately not with Audacity as this that doesn’t use the Jack server.

I’ve had an ongoing issue with the SPDIF inputs though. Under Windows XP and MacOS X it refuses to record more than a few mninutes if locked to another digital unit such as DAT machine and the Saffire software reports the firewire interface has lost it’s connection. This has rendered all SPDIF transfers impossible to do correctly.

The support at Focusrite is very good, you can actually speak to someone! We tried using an external power supply unit (PSU), different firewire cables, checking the type of firewire interface in the Windows machine and upgrading the firmware under MacOS X but all to no avail. This is a repeatable issue under several different computers and OS’s.

Posted by greatbear in Audio Tape, Information Technology, 0 comments

Advent 7055 laptop overheating repair

Advent 7055 running Ubuntu 8.04Just recently I’d been asked to repair what seems to be a common problem with PC type laptops over a couple of years old. Dust gets trapped in the copper fins and the fan of the CPU heatsink and reduces the efficiency of the cooling resulting in regular power off’s by the laptop as it gets over it’s upper temperature setting.

The fix is relatively easy, remove the heatsink unit, blow it clean with compressed air, clean the old CPU heatsink paste off with isopropyl alcohol (IPA) and spread a thin but even film of good quality heatsink paste on the CPU. Put it all back together, keep your fingers crossed and it should be fine!

This has fixed several laptops permanently and with this Advent I could go ahead and wipe the old Windows XP Home from it and install Ubuntu 8.04 that’s fantastic and  installs perfectly without any ‘geeking around’ necessary. My only problem is the fan control from linux, but that’s another story……

Posted by greatbear in Information Technology, 3 comments