rendering full HD to mpeg2 or avchd?

[Adam Stanislav]

Originally Posted by Aaron Holmes

.mpg is just a more-recognized extension than .ts.

It is more than an extension. It is a different file format.

To be more precise, the MPEG-2 standard defines two types of streams: The program stream (PS) and the transport stream (TS).

The PS is for storing an MPEG video in a file, as used in computers, DVDs and such, where the entire file is available at all times. Because it is always available, it has a header which contains the information about the stream, such as the size of the image. Since it is always available, software, such as players and editors, can read it once and either remember it while they are interpreting the video (and audio, etc) data or can discard it knowing they can always go back to the header and read it there. The computer files with the .mpg extension are PS files.

The TS, as its name implies, is for audio-video data that is not within a file (though it can be saved in a file) but is being transported to the system from somewhere else. That is, it is used in live streaming (most notably by digital television). It has no defined beginning, since, for example, you can turn on your TV at any time, or you can switch to a different channel at any time. As such, it cannot have a header at the beginning. Instead, the TS splits the data into fixed-size packets, each packet starting with a special byte that informs the system it is the first byte of a packet. So, when you turn on your TV, it can start receiving anywhere within a packet. The first thing it does is look for that special byte, so it can know where each packet starts. Once or twice a second the TV station will transmit a special packet that contains the same information contained in the PS (.mpg file) header. Until your receiver gets that special packet, it cannot interpret the data inside all those packets that keep coming its way. And since anyone can tune in at any time, it is imperative for that special packet to be sent out often. You may have to wait for half a second or so but of course, to us humans that is a very short period of time, so we do not even notice the wait.

Why have two formats? The special packet the TS has to include regularly increases the size of the data. So, while TS is more flexible, it is a waste of disk (and disc) space, so file-based systems prefer PS.

That said, many MPEG decoders can handle both formats, so renaming a .ts file into a .mpg file may work. But there is no guarantee your decoder does understand the TS format. You would never burn a TS on a DVD because a DVD player is not guaranteed to understand it. Despite the fact a DVD has the video files in a VIDEO_TS directory, it expects PS, not TS.

Vegas understands both PS and TS, and also understands both the .mpg and the .ts extension.

[Stanley Szpala]

thanks guys, I have a decent quality mpg now (m2v encoded at 1920x1080, variable bit rate: max=30Mbps, min=20, mean=25; ts renamed into mpg).

I looked also at mov, but the quality wasn't good enough; maybe there is a way to make it better, but for now mpg is fine.

[Aaron Holmes]

Originally Posted by Adam Stanislav

It is more than an extension. It is a different file format.

To be more precise, the MPEG-2 standard defines two types of streams: The program stream (PS) and the transport stream (TS).

Thanks for the correction, Adam, and the detailed explanation. I suppose I have gotten a bit too comfortable renaming .mts and .m2ts to .mpg, although it has unblocked me many, many times, and continues to do so. Several apps and video hosting services that I use (Facebook is one example) reject all "ts" extensions, but will happily accept, process, and dish them out once they've been renamed as .mpg. Need to send a raw AVCHD clip to Facebook? There you go. Other apps, such as Corel VideoStudio, call every HD MPEG-2 render a .mpg, even when rendering for Blu-ray, which isn't just a TS, but a special hacked-up TS. That's a bit confusing.

Anyway, I'll retract my suggestion of renaming the file to .mpg in the interest of technical correctness (and just keep doing it myself until I hit the wall ;-))

Best,
Aaron

[Adam Stanislav]

Originally Posted by Aaron Holmes

I'll retract my suggestion of renaming the file to .mpg in the interest of technical correctness (and just keep doing it myself until I hit the wall ;-))

That was not my intention. As I said, if the decoder can handle it, why not renaming it if the application does not know it can handle TS. Just as long you are not surprised at those time it does not work.

[Edward Troxel]

In Movie Studio, can you click on the "Custom" button? I know that is limited in Movie Studio for some formats. If you can go to the Custom settings, just click on the Audio tab and you can turn the audio on or off there.