AVCHD Lite vs Motion JPEG - editing ease on the Mac
UPDATE: 11/05/10 – Thanks to your insightful comments, I have written a new article on AVCHD editing on OSX.
With the new camera come a whole slew of editing questions – which format is better, which format lends to easy editing, which format produces the best audio/video… To better educate myself on this topic, I have been trawling the web, finding resources, reviews, experiences of ZS3 users, as well as shooting sample videos using my ZS3 and editing the same on my Mac. It turns out that Motion JPEG is better overall, in terms of quality of audio/video and ease of editing – the two most important benchmarks in my opinion. Intrigued? Read on. Word of caution – this is aimed solely at the hobbyists – people who shoot videos for personal or family leisure. Professionals, well you are just way off base here.
AVCHD Lite is the 720p cousin of the more famed AVCHD format pushed by Sony and Panasonic. Recording at 30fps, at a variety of Mbps (9-17), it is a newer format being implemented by many Point and Shoot cameras. The main pro of shooting in this format is the smaller file size on the card. Everything else touted as a pro, is actually a con. AVCHD uses frame blending (the main reason why the file sizes are smaller) to capture video. It encodes one full frame every X second, the rest being all deltas, which is GREAT for file sizes, but is horrid for editing when converted to another format.
MJPEG or Motion JPEG was the first generation of video compression available to the users back in the day, and arguably is the least efficient way to compress video, but it is on the flip side, the fastest to decode and edit. This is due to the fact that each frame is encoded separately using JPEG compression. It takes the least amount of processing power to encode, edit or playback. It is indeed very wasteful in terms of space consumption. An eight minute sample will take 2GB of space in 720p setting.
Before we start, editing an AVCHD Lite video is NOT natively supported with any of the OS X based video editors. Some have pointed that Final Cut Pro (FCP) can edit the AVCHD files, but I can confirm that it actually converts the MTS video to ProRes 422.
Test Setup
I shot three sequences of videos in low light, out in the snow, and indoors – well lit. All shot in AVCHD Lite format, SuperHigh settings (17Mbps) with Dolby Digital stereo audio, with auto focus in manual settings. I used iMovie ’09 and Final Cut Pro. The former imported the MTS files as AIC (Apple Intermediate Codec) and the latter as ProRes 422 (HD) files. The time taken to convert the MTS files to AIC and ProRes 422 were nearly 80% of the length of the clip. For instance, a clip of a minute took 40 seconds to import to iMovie and FCP.
I repeated the same set of videos with MJPEG, auto-focus and manual settings. There was no conversion necessary and all clips were natively imported in iMovie ’09 and FCP.
The movies were then spliced together, and output as an HD MOV file with bitrate of 9100kbps and two pass encoding. I can post the other setup variables as well. The encoding took the same amount of time, since working with AIC and ProRes 422 is the same as working with MJPEG (native).
Initial Reaction
Video
The time taken for video conversion notwithstanding, the MJPEG format seemed to be a clear winner of the two. Not only was the video sharper, featuring more vibrant and true-life colors, and much less noise (especially compared to the AVCHD videos converted to ProRes and AIC), but also, the quality of the output encoded video was clearly much superior. I could already notice artifacts and loss of quality on the ProRes and AIC encoded videos but this got trebled (nearly) in the final product. The end result seemed to be shot with a normal non-HD camera.
Audio
There was no appreciable difference in terms of audio quality. Even though the AVCHD Lite format supports Dolby Digital audio input, after encoding and compression, there is no discernible difference between the AAC encoded audio from AVCHD Lite and the stereo 2-channel audio recorded with MJPEG.
Preliminary Conclusion
Clearly from an editing standpoint, on the Mac, MJPEG is the clear winner. The editing ease and persistence of quality and low level noise in day-to-day videos makes the benefits of AVCHD (eg. longer recording times) moot. Even though with MJPEG videos are limited to 8 minutes per recording, and translate to roughly 2 GB file (per 8 minutes of video) on the SD card, it more than offsets this lack of compression, with the ease and ability to edit and encode the video on one’s tools of choice be it basic trimming with Quicktime, or Timeline based editing on iMovie and FCP.
My recommendation is a resounding yes for MJPEG. Keep a couple of 16GB SDHC Class 6 cards handy though.