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What Can I Do With a dtvstream *.m2t File?
PostPosted: Fri Dec 10, 2004 7:28 am Reply with quote
k7ar
 
Joined: 14 Nov 2004
Posts: 12




Hi all, what exactly is a .m2t file as recorded by dtvstream? Is it the same format as a .ts file from getatsc? How would one edit such a file, or burn to DVD?

I get a size of approx 8 GB for an hour of 1080i programming, or 4 GB for an hour of SD programming. So clearly some compression scheme would be needed to burn to DVD.

Appreciate any pointers,
Al Rovner, K7AR
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Re: What Can I Do With a dtvstream *.m2t File?
PostPosted: Fri Dec 10, 2004 11:05 am Reply with quote
spitfire
 
Joined: 09 Nov 2004
Posts: 11
Location: Utah




k7ar wrote:
Hi all, what exactly is a .m2t file as recorded by dtvstream? Is it the same format as a .ts file from getatsc? How would one edit such a file, or burn to DVD?

I get a size of approx 8 GB for an hour of 1080i programming, or 4 GB for an hour of SD programming. So clearly some compression scheme would be needed to burn to DVD.

Appreciate any pointers,
Al Rovner, K7AR


A .m2t from dtvstream is just an mpeg2 transport stream, so yes, it's the same as a .ts file. I don't think the .m2t extension is really all that relevant except to whatever application you use to play it back so feel free to name it whatever you want.

As far as editing goes, www.avsforum.com would be a good place to search. In particular, search for HDTVtoMPEG2. It's Windows only at the moment, I believe, but it will let you edit your transport streams to remove unneeded content such as commercials and subchannels. I've found that a typical 45 minute 720p program (with commercials removed) takes up about 4GB of space and a 1080i show uses about 5GB of space. www.doom9.org would be a good place to look for techniques on reducing the size of 1080i content. If you need something for Linux, I think ProjectX, which is written in Java, does similar things as HDTVtoMPEG2, but I'm not very familiar with it and it certainly isn't as user friendly. Also you might consider WM9. Yes, it's an evil Microsoft codec, but it would allow you to compress and fit four, 45 minute 720p shows on one 4GB DVD with virtually no loss in quality. Until something equivalent comes along, Microsoft is it for file size vs quality compression.
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Use mencoder
PostPosted: Fri Dec 10, 2004 12:52 pm Reply with quote
haynals
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Search this forum for mencoder.
Re: What Can I Do With a dtvstream *.m2t File?
PostPosted: Mon Dec 13, 2004 3:20 pm Reply with quote
pdicamillo
 
Joined: 09 Mar 2004
Posts: 68
Location: Needham, MA




k7ar wrote:
Hi all, what exactly is a .m2t file as recorded by dtvstream? Is it the same format as a .ts file from getatsc? How would one edit such a file, or burn to DVD?

I get a size of approx 8 GB for an hour of 1080i programming, or 4 GB for an hour of SD programming. So clearly some compression scheme would be needed to burn to DVD.

Appreciate any pointers,
Al Rovner, K7AR


If you use dtvstream with the "-p all" option (for all packets), the file it creates is the same as what getasc creates. If you use dtvstream to select a particular program, then the .m2t file includes only the packets necessary for that program. It omits packets for other programs, and non-program packets, such as null packets and guide information. Besides saving space, the file is likely to be more compatible with programs which expect a basic MPEG-2 transport stream rather than a stream with mutiple programs and the extra packet types added for DTV.

I have a Samsung SIR-T165 which includes a FireWire input. Using a program I have, I can send the .m2t files to the Samsung through FireWire and view them that way. I've found that usually doesn't work unless I've used dtvstream to make stream file with just the program I want.

Apart from the problem of file sizes, the DVD standard doesn't allow for high-resolution video. It's limited to 640 x 480, and the maximum data rate is 9 mb/sec (for video + audio). Also, it doesn't use MPEG-2 transport streams, so you definitely need to use something like mencoder if you want a DVD that you can play on a DVD player. I save my recordings as data files on DVDs and play them back on my computer or over Firewire. For an hour-long show, I'd use dtvstream to split the 8GB file and store it on two DVDs. I don't mind doing this for a while, since it won't be a problem when the new HD DVDs are available. There's no problem with splitting a stream and watching it from the point where it was split, since MPEG-2 transport streams are designed to be usable starting at any point.
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PostPosted: Tue Dec 14, 2004 10:04 am Reply with quote
Scott Larson
 
Joined: 15 Oct 2003
Posts: 713
Location: Portland, OR




The NTSC DVD standards allow a couple of slightly larger resolutions: 720x480 and 704x480. These aren't 16:9 either but if you flag them as anamorphic, your DVD player will stretch them to 854x480 (or letterbox them).
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What Can I Do With a dtvstream *.m2t File?
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