AVCHD 720p/60 a problem?

Started Feb 18, 2009 | Discussions thread
gweedo Regular Member • Posts: 350
Re: Go read the AVCHD specs

hazydave wrote:

Regardless, the MPEG-2 transport stream is designed for anything that
benefits from small packet writes. It's used on DVD, true, and on
tape, and in satellite transmissions, and a variety of other places.
It's also the format used on Blu-Ray.

Ok, right so far. What do these all have in common? They are formats where you get a fixed bandwidth stream of data. You can "Random access" a DVD or blue ray disk, but they are extremely slow at doing so, and much more efficient when the data is streamed off of them.

The MPEG2 transport stream lets you intermix different tracks, eg: a track for left audio, a track for right audio and a video track, in the same packet. This is important when your streaming, because you have to send all the data in realtime.

Sure, you COULD use Quicktime,
or the closely related MPEG-4 file structure, on flash or HDD media,
but there's little point.

On the contrary, because the MPEG2 transport stream interleaves the data, there is a big point. You spend a lot of time reassembling these packets when using AVCHD while using MPEG4 doesn't have that problem.

With a truly random access device like Flash or HDD, there is no reason to use a stream protocol. You have to with a stream oriented device, but its just a waste of time when you've got a random access device. Better to store the audio as audio and the video as vide than mix it all into packets.

But the real point is that this is for consumers. The AVCHD format is
the annointed successor to DV, HDV, and all of the various and
slightly incompatible MP4 formats used on some of the existing third
tier camcorders (Sanyo for one).

Actually, you have it backwards. AVCHD uses H.264 video and it makes it incompatible by puting it in an MPEG2 stream.

MPEG4 is a standard. There are not variations of it. The standard supports video in a variety of formats and bitrates. But the standard means any editor that conforms to the standard can playback the video.

With an MPEG4 file you can just play it back in quicktime, realplayer or windows wmv player-- as all three of them support the standard. AVCHD you have to find a special program to play it back natively.

Same way with editors. MPEG4 is a standard.

It is only the "annointed successor" to those other stream formats because the camera makers keep advertising it, and people who don't understand the technology keep claiming that its somehow superior.

It offers nothing over MPEG4 on random access media, and all camcorders are going to random access media. This is also why MPEG4 is becoming more popular with Canon choosing it for the 5D, JVC choosing it for their professional camcorders, etc.

old consumers will do, if they edit at all), you can take AVC
directly into your NLE.

Do you realize that AVC and AVCHD are two very different things?

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