MPEG-4 and Drive space

[LASooner]

I have a question that someone might know the answer to. I was wondering if the programs that are saved on the hard drive keep their encoding or are they saved as MPEG 2 files? Because you would have to believe that shows recorded in MPEG 4 would take up less hard drive space than MPEG 2. And the 30 hours of HD space on the 622 would actually hold more HD than that.

I realize that most of the current MPEG 4 is just MPEG-2 with a MP4 header

 

[drjdan]

I understand that the programs are stored in a raw form that is sent by the sat.

 

[pdxsam]

Correct data is stored as it's received from the satellite.

The true Mpeg-4 streams do in fact take up less space than Mpeg2 counterparts.

Not much less right now but as the encoders get better.. the amount of compression with get better with it.

Sam

 

[Kirby Baker]

Right now the MPEG4 streams (at least the captures I have from StarzHD) are no smaller than an MPEG2 movie. StarzHD is coming through at around 15mbit/sec. If they ever get the MPEG4 encoders working fully, I would expect that the bitrate will take a significant drop, then you might see some space savings, but for now, no savings are being realized unless its coming from the CBS/NBC HD locals, which I highly doubt are running below 14-15 mbit/sec.

 

[shanewalker]

As to why the new channels footprint is the same as MPEG-2 content...Isn't that because none of the purported MPEG-4 channels are really MPEG-4, but rather MPEG-2 w/ header information that precludes them from being 'seen' on older receivers (as mentioned above)? Or has this changed--is StarzHD now truly MPEG-4?

 

[Kirby Baker]

No. StarzHD, NFL HD, and the HD locals (outside of NYC) are true MPEG4. And StarzHD and NFL HD have been 100% true MPEG4 since they went live a while back.

 

[Smith P.]

More info you could see there : http://www.satelliteguys.us/showpost.php?p=609801&postcount=43

 

[shanewalker]

Interesting...things you learn. Thanks for the link.

Is the MPEG-4 transcoding the reason for the HD locals softness relative to OTA? I noticed immediately the difference in the PQ and made a point to maintain diplexed connections on all my new recievers to my roof antenna because of this (and as a safety against rain fade).

 

[Kirby Baker]

Thats part of the problem I would imagine, especially on the 1080i channels. Not sure how they 720p (ABC and FOX) channels are, since I only receive locals in MPEG2 right now.