H.264 / VC-1 codec questions at DVinfo.net

Mark Donnell · May 17th, 2006, 06:11 PM

I was hoping someone could tell me if the amount of compression applied by the H.264 or the VC-1 codec is adjustable. My thinking behind this is that when we eventually begin encoding high-def DVDs (either HD or Blu-ray), standard DV at 25 Mbs is well within the 36 Mbs maximum data rate spec for high-def DVDs and would require no compression, just format conversion, to play on these DVDs. On the other hand, DVCPRO-HD from the Panasonic HVX-200 at 100 Mbs would require at least 3:1 compression to fit within the DVD spec. If the amount of compression in the H.264 and VC-1 codecs is fixed, does someone know what those compression ratios are ?

Giroud Francois · May 18th, 2006, 02:16 AM

VC-1 is in fact wmv9 so same specifications apply (variable bandwith)
H264 like all mpeg compressions is also variable bandwith.
almost all codecs i know offers more or less at least a "quality" setting allowing to change the compression used.
The only one is DV, since DV is fixed to 25MB/s.
For sure, the goal of a high compression codec, like VC-1 or H264 is to produce small files while keeping good quality, so using them with very high bandwith is counter productive since it should not increase a lot the quality, just the file size.

Mark Donnell · May 24th, 2006, 02:07 PM

Thanks for the response, Giroud. I have another question for the group. What is likely to be the best way to encode standard DV onto HD-DVD discs ? Obviously, no extra compression is needed since a 25 Mbs data stream is within the capacity of the disc, so the ideal codec would do as little compression as possible.

Laurence Currie-Clark · May 24th, 2006, 07:07 PM

I did many tests about getting DV quality with H.264. At 9mbit the quality was equal and at 3 the quality was still excellent but lost a bit of sharpness.

Kevin Shaw · May 24th, 2006, 10:44 PM

Quote:

Originally Posted by Mark Donnell

What is likely to be the best way to encode standard DV onto HD-DVD discs ? Obviously, no extra compression is needed since a 25 Mbs data stream is within the capacity of the disc, so the ideal codec would do as little compression as possible.

The easiest thing to do for now would be to convert to MPEG2-TS at the highest data rate which work on the disc for SD content, or upsample to HD resolution so it will definitely work at the full 25 Mbps data rate. It will be nice to finally be able to deliver to customers something close to the quality of what we record in our cameras!

May 17th, 2006, 06:11 PM	#1
Mark Donnell Major Player Join Date: Nov 2005 Location: Silver City, NM Posts: 385	H.264 / VC-1 codec questions I was hoping someone could tell me if the amount of compression applied by the H.264 or the VC-1 codec is adjustable. My thinking behind this is that when we eventually begin encoding high-def DVDs (either HD or Blu-ray), standard DV at 25 Mbs is well within the 36 Mbs maximum data rate spec for high-def DVDs and would require no compression, just format conversion, to play on these DVDs. On the other hand, DVCPRO-HD from the Panasonic HVX-200 at 100 Mbs would require at least 3:1 compression to fit within the DVD spec. If the amount of compression in the H.264 and VC-1 codecs is fixed, does someone know what those compression ratios are ?

May 24th, 2006, 02:07 PM	#3
Mark Donnell Major Player Join Date: Nov 2005 Location: Silver City, NM Posts: 385	DV on HD-DVD Thanks for the response, Giroud. I have another question for the group. What is likely to be the best way to encode standard DV onto HD-DVD discs ? Obviously, no extra compression is needed since a 25 Mbs data stream is within the capacity of the disc, so the ideal codec would do as little compression as possible.

May 18th, 2006, 02:16 AM	#2
Giroud Francois Inner Circle Join Date: Feb 2004 Location: switzerland Posts: 2,133	VC-1 is in fact wmv9 so same specifications apply (variable bandwith) H264 like all mpeg compressions is also variable bandwith. almost all codecs i know offers more or less at least a "quality" setting allowing to change the compression used. The only one is DV, since DV is fixed to 25MB/s. For sure, the goal of a high compression codec, like VC-1 or H264 is to produce small files while keeping good quality, so using them with very high bandwith is counter productive since it should not increase a lot the quality, just the file size.

May 24th, 2006, 07:07 PM	#4
Laurence Currie-Clark New Boot Join Date: Jun 2005 Location: Nivelles, Belgium Posts: 22	I did many tests about getting DV quality with H.264. At 9mbit the quality was equal and at 3 the quality was still excellent but lost a bit of sharpness.