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HD MPEG-2 vs. AVC
I believe that a number of members prefer rendering to (Sony) AVC over Mainconcept MPEG-2 (M2V) when creating Blu-ray files. WHY??!! I ask this because in a real-world experience I have found that AVC requires more overhead to deal and work with. Take, for example, the 3 hour Conservative Bat Mitzvah service that I shot last Saturday morning. My Sony HDR-AX2000 HD Camcorder recorded the event in AVC at 21Mbps. I rendered it both with Sony AVC and MainConcept MPEG-2 M2V files. The Sony AVC was rendered at 18Mbps, took 4 hours 19 minutes to render, and is 22.83GB in size. Importing it in to DVD Architect 6, the disc space used is 24.2 GB. The MainConcept MPEG-2 file was rendered at 17.8Mbps CBR, took 2 hours 16 minutes to render, and is 22.75GB in size. Importing it in to DVD Architect 6, the disc space used ALSO is 24.2 GB. So why does anyone prefer AVC over MPEG-2? Have I just experienced an anomaly, or is this typical? The two resulting Bluy-ray ready files look identical to me as far as video quality, too. I thought that AVC compresses more efficiently for a given quality, but in this case it’s a tie! Can anyone explain this, please, as for future reference I would like to know if it’s maybe just the length of the video that created these differences, as well as similarities, or if others, too have experienced HD MPEG-2 to render soooo much quicker than AVC files, have them take up the same space and look just as good as the other? Was it also maybe perhaps because I compressed the AVC from 21 to 18Mbps? Thank you in advance.
Rich Kutnick
VIDEO IMPRESSIONS -
3 Replies
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[Rich Kutnick] “I believe that a number of members prefer rendering to (Sony) AVC over Mainconcept MPEG-2 (M2V) when creating Blu-ray files. WHY??!!”
I can’t say why because I prefer MPEG-2 for my Blu-ray projects because it’s easier to work with and renders faster and time is money.
[Rich Kutnick] “I rendered it both with Sony AVC and MainConcept MPEG-2 M2V files. The Sony AVC was rendered at 18Mbps, took 4 hours 19 minutes to render, and is 22.83GB in size. Importing it in to DVD Architect 6, the disc space used is 24.2 GB. The MainConcept MPEG-2 file was rendered at 17.8Mbps CBR, took 2 hours 16 minutes to render, and is 22.75GB in size. Importing it in to DVD Architect 6, the disc space used ALSO is 24.2 GB. So why does anyone prefer AVC over MPEG-2?”
What you’re not realizing is the quality difference. You need 25Mbps MPEG-2 to equal the quality of 16Mbps AVCHD. So you can get higher quality AVCHD at a lower bit-rate which means you can put more AVCHD on a Blu-ray at the same quality as MPEG-2. You rendered at the same bit-rate so you got the same file size but you did not get the same quality even though you couldn’t tell the difference.
[Rich Kutnick] “The two resulting Bluy-ray ready files look identical to me as far as video quality, too. I thought that AVC compresses more efficiently for a given quality, but in this case it’s a tie!”
If you didn’t see any difference in quality that only means that the quality difference was imperceptible at that bit-rate but it was there. As the bit-rate drops, the difference in quality will show the AVCHD to hold up better at lower bit-rates.
Only you can decide if the quality is the same. If you place your render on the Vegas timeline above the original and place the track composite in Difference mode you will see the difference between the original video and the render. That is the true way to judge quality loss. A totally black frame means no difference and therefore no loss of quality. If your eyes can’t see the difference once it’s on Blu-ray, is there any difference? (that’s kind of a “if a tree falls in the forest and no one is there to hear it does it make a sound?” question) Some people are happy if they can’t see any quality difference, and that’s OK. It doesn’t mean that the difference isn’t there and that it can’t be measured. All that matters is if you are happy with the quality.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
That’s just it — AVC delivers better quality for the same bit budget, or roughly twice the content at the same quality. Obviously, you’re not going to render anything better than your original material no matter what the bitrate. That’s the limit Rich seems to have hit on his example.
When very well encoded, AVC delivers about twice the coding efficiency. It does this at the price of complexity.. it’s probably at least 3x-5x as difficult to encode AVC, and about the same to decode it, versus MPEG-2. And it’s taken the industry awhile to develop the technology to encode it well — first generation AVC camcorders didn’t match MPEG-2… they didn’t have the computational performance to encode better AVC.
Get used to it.. things do advance. There’s a new one on the horizon, HVEC (High Efficiency Video Coding), which was accepted by the ITU as H.265. This promises twice the coding efficiency of AVC. It’s going to be 4-5x as difficult to encode, and about 3x as difficult to decode.
And just when my PC was getting fast enough to edit AVC without a great deal of pain 🙂
-Dave
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Learning this myself. On two movies I am experimenting with: “Story of Ruth” and “Solomon” which are very old movies, each about 2 and half hours long, I used the Bitrate Calculator which gave me VBR 2-Pass Bitrate: Max 43,600 AVG 18,550, and MIN 7,400. I added 5 minutes to the total time for safety of margin. When I switched to DVDA 6.0, it showed with both, I only used 80% of the disc, but it wanted to recompress both videos and burned to the BD-RE which I tested on my television. Ruth played fine but Solomon would not play at all.
Reading various posts on AVC vs m2v, combined with Sony stating 9 hours can fit on a 50 Gig Blu-Ray disc, now trying the experiment on using Sony AVC to render both videos, but customized the template from 16,000,000 bits per second to the minimum from the Bitrate calculator of 7,400,000 bits per second. Did notice on the computer while rendering to avc the picture quality appears to be sharper than when I rendered in m2v format. However, will not know for sure until after I render both, import to DVDA 6.0 to place on a 50 Gig BD-RE and test on the television itself. If both will play, then I know the two I have created for the exposition should work as well as the time is the same as those old movies.
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