ATSC mpg file sizes

[David]

OK, I have completely rebuilt my PVR system and my ATSC 110 is now recording through the intervideo mux on a fairly consistent basis. The two versions of the cyberlink mux files still do not work, and I don't want to mess around too much more.

I've noticed that the recorded files are much larger than those produced by my pvr-250. One hour from the PVR-250 is about 1.8 GB at medium level recording, whereas the ATSC-110 runs a little over 5 GB for the hour. I don't think that setting the recording level has any affect on the final file size. I thought the .dvr-ms files were marginally larger, but not 2.5 times larger.

Are these file sizes typical? Would a different mux produce smaller files? I understand that the demuxing simply removes the dvr-ms container, so I would expect the mpg file to be slightly smaller than the dvr-ms version. Could it be saving more than one stream?

[sub]

I think these are fairly normal file sizes for ATSC. With digital television, the quality setting is ignored since the digital stream has already been encoded by the broadcaster. You are dependent on the broadcaster as to how big the resulting file will be.

The extra overhead of DVR-MS is insignificant, so its not really worth looking into usin .mpg files just to save space over .dvr-ms.

I'm guessing the only way you'd be able to reduce these sizes is by transcoding the files to something like xvid/divx/wmv etc.

[David]

The dvr-ms files can't be played on my DSM-320 without transcoding. I think they need to be transcoded for the MVP as well?

I put all the effort into recording straight to mpg to avoid transcoding, either in postprocessing.bat or "on the fly" during playback. It also seemed cleaner for running comskip, etc.

The file sizes are also causing problems, so I may need to transcode anyway. Bummer!

Thanks Sub. Great software. I keep blabbing about it to everyone who's interested.

[sub]

The dvr-ms files can't be played on my DSM-320 without transcoding. I think they need to be transcoded for the MVP as well?

I put all the effort into recording straight to mpg to avoid transcoding, either in postprocessing.bat or "on the fly" during playback.

Ok, having a device that wont play .dvr-ms is a decent reason for wanting to convert to .mpg.

[-stattik-]

It's all about resolution and framerate. The PVR 250 records in 740x480@29.97 FPS (In your case)

An ATSC stream typically broadcasts in one of two formats:

1920x1080@29.97 FPS

1280x720@59.94 FPS

I get 4-8 GB an hour depending on the format.

[David]

Makes sense. I just didn't have a frame of reference for it yet. My playing around hadn't produced such large files.