Tag Archives: AVCHD

Transcoding MTS/M2TS AVCHD Video Into AVI Files with Free Software

dscn1233.JPGThis holiday season, I was an extremely lucky recipient of a Sony HDR-SR5 video camera with a whopping 40GB hard drive inside.

When I opened it, the first question in my head was not atypical of a Linux users’ train of thought:

“Is it compatible with Linux?”

The answer was a tiny bit more complicated than I imagined, and immersed me into the otherwise unknown world of video transcoding, which is something millions of people do every day but probably never think about it. The best example is on YouTube, where it happens behind the scenes in the Google computing cloud, and everything “just works.”

I’ve read a few things about the format the camera uses, called AVCHD. Even in Windows (or OSX for that matter) many people have headaches with the AVCHD format, so I figure that Linux users are probably going to be having a helluva time trying to get it to work.

The files the camera generates are compressed at an incredible 15:1 ratio. I’ve seen it mentioned that a Standard Definition compressed clip of is actually larger in file size than an HD clip in AVCHD format.

The compression is where a majority of the AVCHD format complaints come originate from, since there is not much out there in terms of being able to edit video stored in the format without uncompressing it first. It takes some rather respectable computing horsepower to actually convert the files into an uncompressed format that can be played with in a video editing software package. Using the method detailed here, it takes about 5-6 minutes to uncompress and transcode a minute of video, on an Intel Core2Duo running at 3.2GHz with 4GB of RAM and a 10,000RPM hard drive – OUCH!

When plugging in the Sony HDR-SR5, it functions as a USB Mass Storage Device. Copying files from the camera to the computer is a simple drag n’ drop affair. This would be a familiar process to anyone who has used a digital camera and imports pictures to their computer.

It would certainly be faster to playback the videos in real-time and capture them using the component outputs from the camera… but that wouldn’t be a challenge. I’ve never actually installed the software that came with the Sony Handycam, so I’m not sure what I’m missing out on, but it doesn’t seem like all that much, to be honest. I wouldn’t be surprised if it was the typical Sony software suite that is about as useless as the media it is distributed on.

Let’s get down to the meaty bits, shall we?

The first thing I searched for was “AVCHD Linux” and found a post over at AVS Forum. On a side note, my Google-Fu is really spot on lately.

That post is a gold mine. It literally contains everything we need to transcode the video into formats of our choosing that are usable in non-linear video editing programs such as Avidemux or Cinelerra.

m2tstoavi is the best information I have found (so far!) to uncompress the AVCHD video files on my camcorder and convert them into a .AVI file in Linux.

Installation is very simple, all it requires in Ubuntu is a quick apt-get install:

sudo apt-get install mplayer ffmpeg x264 faad2 faac a52dec mencoder faad libfaad2-0 libfaad2-dev subversion csh

Then edit the install script as noted in the README to grab the newest version of ldecod. Everything else is completely automated – nice job Axel!

I did need to modify the settings a tiny bit to actually get audio synchronized as well as fix a possible issue with the script itself. I had problems until I commented out the echo ffmpeg yadda yadda part. When modified, it runs the following commands:

xporthdmv -hn $file 1 1 1 && mv bits0001.mpa $audiofile
ldecod -i bits0001.mpv -o $videofifo &
ffmpeg -r 29.97 -s 1440x1080 -i $videofifo -i $audiofile -vcodec mpeg4 -sameq -acodec copy -aspect 16:9 -b 15000k

I’m using the m2tstoavi.fifo script that uses named pipes (denoted above with dollar signs) to stream the output of one command into another. It is efficient with disk space and does not fill up the drive as the regular m2tstoavi script does, not sure why the fifo version is not the default. Ah well, nothing is perfect.

Once installed, I just run this command to convert every MTS video in the current directory to .AVI files:

./m2tstoavi.fifo *

It turns this proprietary format mess:

source-mts.png

Into precious memories:

output-mts.png

All in all, I’m glad I don’t need proprietary software for this conversion. I really wish it were faster – but here’s the point of this exercise:

I never used Windows software, so I don’t know what I’m missing. I’m happy with the solution I have, and if 20 people comment on this post and say they can edit HD video in realtime, good for them.

If they do, then I would have a better reason to upgrade to a quad-core CPU.

Here’s a (VERY unpolished!) video talking about the process in a little bit more detail, and showing the actual encoding process and the finished result. I’m not responsible for anybody tripping out at the end on my extremely crazily bad camera skills in the rendered video.

Oh yeah, and for those of you who were wondering, I also received quite possibly one of the best books I’ve read in a long time… it’s all about how cool Eric S. Raymond is ninjas are.

ninja.png