Advantages of New MPEG4 Upgrade...

GTPBoy

Active SatelliteGuys Member
Original poster
Jan 23, 2005
17
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I would just like to start off by thanking Scott, Sean and all the Satelliteguys Staff Members for giving us so an excellent site to rant, rave, discuss and argue about everything Satellite.

Now I have a quick question about the upgrades that were completed today. From what I understand is that the new harmonic encoders are now in place and active. I also understand that MPEG4 streams are most likely not too far in the future, and this will enable more streams in the current allocated bandwidth. My biggest concern or question is regarding the quality of MPEG4 to MPEG2. From what I understand, MPEG4 looks great at a standard bitrate, but what about high action scenes? My experience with MPEG4 is that any real time encoding of the stream using a constant bitrate can result is excess bandwidth being wasted in low action scenes and insuffucient bandwidth for high actions scenes, causing pixelation. The usualy solution is that you can do multipass/bidirectional encoding of the stream and allocate the data where it is needed. But from what I understand the stream is being converted and distributed on the fly. Typical variable bitrates I use for MPEG4 are usually around ~1200Kb/s, some scenes will be 400 and others 1600, assuming they want no pixelation, they would choose the highest possbile bitrate, am I right or wrong? These bitrates I refer to are usually at a much lower resolution than HD, typically 640x240 or so. I would imagine that HD would be alot higher, maybe even as high as 2500 to 3000Kb/s. Is that bitrate much lower than they currently broadcast HD at? Im not sure how high HDTV is, or if the encoders are pre-emptively scanning ahead and anticipating larger bandwidth allocation and dynamically borrowing it. I'm just hearing some people complain about PQ loss and i know that all DBS providers will be going this route eventually, I just want justification that we wont be sacrificing the thing that we love most about our favorite DBS solution, Voom. :)


Im not making a statement, but just looking for clarification...

Thanks again,

Brendon
 
Not sure about MPEG-4. Some say it is good others say it is not. However, we are not there yet. I am told that they will be tweaking to give us the best PQ. Right now, there are pixelation on some channels. We are keeping track of these in this thread: http://www.satelliteguys.us/showthread.php?t=55293 I am in contact with the engineers and they have asked for our feedback to improve the PQ so it will be helpful to post as much detail as possible in that thread so that the PQ could be improved.
 
MPEG-4 AVC HP (I am not sure if the Harmonic's encoder is AVC HP or AVC MP) will be able to match MPEG-2 with 60~70% of the bitrate, assuming the sources to both encoders are the same high bitrate (as in 45 Mbps MPEG-2 or better) ones.

My guess is that most MPEG-4 AVC HP broadcaster will choose anywhere between 8 to 15 Mbps...

If MPEG-4 AVC HP is trancoded from low-bitrate (that is what's on right now < 19 Mbps) MPEG-2, it may look worse since transcoding can only be as good as the source.

Hong.
 
hongcho said:
If MPEG-4 AVC HP is trancoded from low-bitrate (that is what's on right now < 19 Mbps) MPEG-2, it may look worse since transcoding can only be as good as the source.

Hong.

Or in more simple terms... the more times you encode/decode the worse the result. :)
 
Hongcho, thanks for your reply. Isnt alot of the content going to be transcoded across from an inferior source? My biggest concern is going to be massive pixelation on a 70" sony when watching COPS on CourTV and have to move about 50 feet from the tv for it to bearable. I guess eventually when the source material is all digital and superior quality all will be good, its just that technological hump until we get there...

Thanks,

Brendon
 
HookedOnTV said:
Have they mentioned which model encoders they are using? Would be interesting to look at the spec's.

sean posted a link to a thread about the encoders in the 2nd message in this thread.
 
Sean, why don't you put the engineers in direct contact with me? If they want a critic, I am probably your best option here. I would love to help them out, I can see the tiniest flaw in any picture and believe me, I see them and they bug the Hell out of me. Right now, I am not at all pleased with the new results.
 

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