Video compression on BD - Blu-ray Forum

torimusic · 03-30-2006, 09:27 PM

Will the high def video be compressed on BD in much the same way as it is compressed with MPEG-2 on DVD's ?

Marwin · 03-31-2006, 08:49 AM

Blu-ray will support playback of MPEG-2, MPEG-4 AVC, and VC-1 in all players and hardware. Which video codec is used to encode a movie is up to each individual studio to decide.

AV_Integrated · 03-31-2006, 02:43 PM

Yes, MPEG-2 is likely to be used on a lot of discs, but it should not be confused with DVD. I believe DVD MPEG2 is limited to 9Mbs data rate - Blu-ray operates at 45Mbs. Do the math - that's 5 times the data transfer rate within Blu-ray vs. DVD with the same audio/video codec.

I had heard several years ago something which seems to be playing out as truth. These older codecs, like MPEG2 are superior at higher bit rates than the newer ones, like MPEG4. In all cases? I'm not sure, but the Toshiba HD-DVD demo showed a bunch of trailers... they all looked fairly bad, except the King Kong trailer. Bit rate on all were supposed to be 36Mbs. The compression? For all movies EXCEPT King Kong, MPEG4 was used. For King Kong? MPEG2.

The concept is that these newer codecs are being designed for the highest possible quality at low bit rate delivery (Internet). These codecs do a phenomenal job throwing away the least amount of data as possible and preserving image quality when bandwidth is limited.

But, when bandwidth is wide open and quality really counts, those same codecs are already throwing critical image data away. MPEG2, which looks far worse at low bandwidth, starts looking a lot better, quickly, when it is given a better pipeline to run data through. The end result is that MPEG2, at higher bandwidths, outperforms the newer codecs because it is doing what MPEG2 was designed for. MPEG4 wasn't designed for high bandwidth video presentation, it was designed for low bandwidth video presentation.

How AVC and VC-1 look? Those will be determined down the road... and more will need to be looked at with MPEG4 before any final consensus is reached by the HD community.

thunderhawk · 04-01-2006, 10:44 AM

Quote:

The concept is that these newer codecs are being designed for the highest possible quality at low bit rate delivery (Internet). These codecs do a phenomenal job throwing away the least amount of data as possible and preserving image quality when bandwidth is limited.

That's why I think the H.264 (MPEG-4 Part 10) AVC has got several profiles. The ones I'm familiar with is the Main Profile (codec optimised for DVD quality) and the High Profile (codec optimised for HD quality) but then again it's a big question if the studio's use the best configuration of the codec since one configuration can't be used all the time (aspect ratio changes for example). Overview: http://en.wikipedia.org/wiki/H.264#Profiles
It's true that when you only consider the bitrate, MPEG-2 is surperior without optimising the codecs. What I fear is, that studio's will avoid all the troubles and just use one codec, always at the same configuration, therefor loosing discspace... However, not all discspace will always be used ofcourse (as with DVD).

AV_Integrated · 04-03-2006, 04:58 PM

I think that, as with the hardware, the software to create HD discs will need to go through a pretty steep learning curve. Video jumping from format to format and properly compressing the video for optimal video quality and maximizing data rates to fit onto a specified disc size will be tough to accomplish.

Already, this is an ongoing issue with DVDs as one disc may look fantastic while another looks horrible. With HD, any flaws are just pronounced that much more. I am unaware of how many tests have been run comparing the different CODECs to one another under controlled - and less than controlled circumstances with different video material.

But, once the software is in place that can 'do it all' then it ALL needs to be tested out to see what really will give us the best results. At some point it'll all be automatic. A 1080p master will be made and then the compressors will go to work and know exactly what to do to give you perfect results. I have zero belief that it is at this point yet.

03-30-2006, 09:27 PM	#1
torimusic New Member Member since:Mar 2006	Video compression on BD Will the high def video be compressed on BD in much the same way as it is compressed with MPEG-2 on DVD's ?

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03-31-2006, 08:49 AM	#2
Marwin Developer Top contributor Member since:May 2003 Blu-ray collection:10 DVD collection:5 iTunes collection:1	Blu-ray will support playback of MPEG-2, MPEG-4 AVC, and VC-1 in all players and hardware. Which video codec is used to encode a movie is up to each individual studio to decide.

03-31-2006, 02:43 PM	#3
AV_Integrated Senior Member Member since:Jan 2005	Yes, MPEG-2 is likely to be used on a lot of discs, but it should not be confused with DVD. I believe DVD MPEG2 is limited to 9Mbs data rate - Blu-ray operates at 45Mbs. Do the math - that's 5 times the data transfer rate within Blu-ray vs. DVD with the same audio/video codec. I had heard several years ago something which seems to be playing out as truth. These older codecs, like MPEG2 are superior at higher bit rates than the newer ones, like MPEG4. In all cases? I'm not sure, but the Toshiba HD-DVD demo showed a bunch of trailers... they all looked fairly bad, except the King Kong trailer. Bit rate on all were supposed to be 36Mbs. The compression? For all movies EXCEPT King Kong, MPEG4 was used. For King Kong? MPEG2. The concept is that these newer codecs are being designed for the highest possible quality at low bit rate delivery (Internet). These codecs do a phenomenal job throwing away the least amount of data as possible and preserving image quality when bandwidth is limited. But, when bandwidth is wide open and quality really counts, those same codecs are already throwing critical image data away. MPEG2, which looks far worse at low bandwidth, starts looking a lot better, quickly, when it is given a better pipeline to run data through. The end result is that MPEG2, at higher bandwidths, outperforms the newer codecs because it is doing what MPEG2 was designed for. MPEG4 wasn't designed for high bandwidth video presentation, it was designed for low bandwidth video presentation. How AVC and VC-1 look? Those will be determined down the road... and more will need to be looked at with MPEG4 before any final consensus is reached by the HD community.

04-03-2006, 04:58 PM	#5
AV_Integrated Senior Member Member since:Jan 2005	I think that, as with the hardware, the software to create HD discs will need to go through a pretty steep learning curve. Video jumping from format to format and properly compressing the video for optimal video quality and maximizing data rates to fit onto a specified disc size will be tough to accomplish. Already, this is an ongoing issue with DVDs as one disc may look fantastic while another looks horrible. With HD, any flaws are just pronounced that much more. I am unaware of how many tests have been run comparing the different CODECs to one another under controlled - and less than controlled circumstances with different video material. But, once the software is in place that can 'do it all' then it ALL needs to be tested out to see what really will give us the best results. At some point it'll all be automatic. A 1080p master will be made and then the compressors will go to work and know exactly what to do to give you perfect results. I have zero belief that it is at this point yet.

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