AVCHD (1080i) ve Motion JPEG (HD)

[pemongillo]

I have a Panasonic Lumic DMC GH-2 camera. My knowledge of video is still minimal. Can anyone offer an explaination of the difference between these two formats and what I should be using each for? A link to a good explainiation would be good as well.

Thanks
Paul

[edDV]

Motion JPeg is a parade of JPeg stills making a video stream.

>Advantage: you get all the frames

>Disadvantage: no motion compression so either files are larger or quality is less.

AVCHD is MPeg H.264 AVC.

>Advantage: More compression efficiency (i.e. better image quality for a given bit rate)

>Disadvantage: More difficult to edit since there is only one full frame every 15 followed by difference frames. In order to edit to frame accuracy, h.264 has to be decoded to a frame stream. This is lossy.

[pemongillo]

Thanks edDV. So let me get this straight. I am not likely to see any difference in quality, but AVCHD is compressed more so takes less storage. It is however more difficult to edit. Does PowerDirector 9 decode to a frame stream to make editing eaisier in AVCHD?

Bottom line, shoot Motion JPEG if you have the space. I assume the sound quality would be the same?

The U-Tube comparisons I have watched leave me unsatisfied. I am skeptical of methods and doubtfull that U-Tube would be the place to do a comparison.

Thanks Again

[poisondeathray]

GH2's MJPEG mode only shoots 720p30 (1280x720) - smaller frame size

The 24p mode shoots AVCHD @ 1920x1080 24Mb/s , but the other AVCHD modes bitrate drops to 17Mb/s

But 24p in general can be difficult to shoot properly (movements have to be slow and controlled)

Youtube comparisons can be misleading becaues Youtube re-encodes everything

Now 60i vs. 24p - you're going to have to do some reading on interlaced vs. progressive. It's a big topic and many disucssions and articles on it here and other sites

[pemongillo]

Thanks Mr Deathray.

[edDV]

Thanks edDV. So let me get this straight. I am not likely to see any difference in quality, but AVCHD is compressed more so takes less storage. It is however more difficult to edit. Does PowerDirector 9 decode to a frame stream to make editing eaisier in AVCHD?

Not the same. Every camera has a unique design based on the chipset running the camera. Most early digital cameras tacked on MJPEG video because the chipset already was doing JPEG for stills. To fit into SD flash media serious bitrate compromise was used and I mean compression on the order of 60-120x which is very poor video. Audio compression wasn't supported by these early chipsets so uncompressed 8 bit mono at very low bitrate was used (ie lower than telephone quality).

Now if you did MJPEG compression on a computer, you could choose the quality you want, but with a camera you have no choice other than read the specs before purchase. Note that DVD quality MJPEG video would require about 8-16 MB/s (64-128 Mbps) which would fill a 8 GB flash card in 12-24 minutes. Camera designers didn't think that would fly so reduced quality about 75%.

As for h.264, read the user reviews. Most users don't have the computer horsepower for h.264.

Bottom line, shoot Motion JPEG if you have the space. I assume the sound quality would be the same?

The U-Tube comparisons I have watched leave me unsatisfied. I am skeptical of methods and doubtfull that U-Tube would be the place to do a comparison.

No not the same. Each camera is a separate design although some share the same chipset.

Youtube compresses again so I agree they are a poor standard of comparison.