Why does DVD Architect want to recompress everything?

[Tom Roper]

Originally Posted by Randall Leong

That's a bit strange. I get a similar warning--but it specifies that the bitrate ceiling mainly applies if I'm using a red-laser disc..

The warning is there for BD25/50 as well. Again, DVDA even if you stay below the recommended ceiling, will peak at up to 40 mbps. You've got plenty of bit rate headroom, especially considering that Blu-ray is 4:2:0, with AVC you don't need more. You can probably get by with a whole bunch less, but I know...you want to see the big numbers that the commercial disks have. You will, at 25 mbps.

One of the things I've found, is I can let DVDA recompress to AVC at 18 mbps, with peaks to 30-34 mbps, ON red laser DVD media, and have it play back without skipping and stuttering on many Blu-ray players. I've seen these DVD disks playback smoothly on Samsung, Panasonic and Sony players to name a few. You can't remotely get away with that using mpeg-2. For all but the PS3 which can 2x double spin a DVD for a higher read rate, high bit rate mpeg-2 (even 25mbps) chokes most any of the standalone Blu-ray players I have tried. But not AVC 18mbps VBR, and you get a nice peak headroom much higher.

[Bill Sepaniak]

Here are the steps I have been using to get DVDA not to recompress using an MPEG2 workflow:

1. The Source files were quicktime 24p;
2. Source files are encoded in Main Concept Reference using the following settings (not the template settings):

A. MPEG-2 : 2 Pass
B Blue Ray(HD) / NTSC
C. Bit rate: variable : target: 20mbs - max: 27mbs
D. Frame rate: 24 progressive
E. Audio: MPEG audio: 224kbps

3. Main Concept will convert the quicktime into a .mpv (video file) and a .mpa (audio file). It may take some time to render this out. I just finished an 1:53 show. The quicktime master file was 66 gigs, and it was an overnight render.

4. Right click on the .mpv file and rename the file to change the extension to .mpg. DVDA doesn't like .mpv.

5. Open the .mpa (audio file) in Sound Forge and save it as an AC-3 and put it in the same folder where your re-named .mpg file resides.

6. When you launch DVDA, open the preferences, and make sure that all of Blueray video settings match the settings that were used when you compressed the source file in Main Concept. Since your .mpg file was compressed with a variable bitrate, use the maximum bitrate setting for that file. For the show that I just did with the 20-27mbs variable bitrate, I used 27mbs as the DVDA bitrate. The same with the audio: make sure it is AC-3 Dolby and it matches what you converted in Sound Forge. If any of the settings don't match, DVDA will want to recompress.

7. Drop the .mpg and the AC-3 files on the time line, select Make Blueray Disc, and just follow the steps in the Blueray burning wizard. If all the video and audio settings in the files match what you selected in the preferences, there should be no recompression.

I have done 5 projects over the last 10 days using the above workflow, and they have all come out without a hitch with no recompression.

However, as with most things in life, " ... your mileage may vary ..."

[Chris Gotzinger]

Thanks for the info, Tom. I've found a program that does what I want for $100. It's called TMPGEnc Authoring Works, it accepts my high bit rate MPEGs without recompression. It also accepts 5.1 Dolby or PCM. That's all I need.

Originally Posted by Tom Roper

I have never seen 40 mbps CBR mpeg encodes on commercial disks, they are always variable, but I suppose it's possible.

There are few. If you look at the list in this thread (starting at post #2), you'll find a bunch of IMAX discs use 40 Mbit CBR:
NEW Unofficial Blu-ray Audio and Video Specifications Thread - AVS Forum

There are other MPEG discs with very high average bit rates, for example:
Click (2006) = 35.71 MBit
The Crow (1994) = 34.43 MBit

IMAX movies are short, so there's no reason to use VBR and try to save space. The same is true for my film. It fits on 25GB at a maxed out bit rate, so why not go for the least compression possible.

Originally Posted by Bill Sepaniak

C. Bit rate: variable : target: 20mbs - max: 27mbs

Thanks for your workflow, Bill.
I added grain to my film, and MPEG @ 20 Mbit avg, 27 Mbit max would be too compromising for that kind of footage. I do understand that this would work though, because it stays below the 28 Mbit that DVDA hates so much.

[Tom Roper]

I've always liked TMPGEnc and other simple to use (Pegasys) products, and have used DVD Author, the predecessor to Authoring Works, but in the end, it's a consumer product that doesn't grant a Dolby license for commercial use. That and the BDMV output is mpeg-2 only.

Also the reason to not go for an always-maxed CBR bit rate is that not all Blu-ray players can avoid choking, since a number of Blu-ray standalone players can't read BD-R/RE media (if at all) at the same speed as BD-ROM. It may just come down to who you are targetting your collaboration toward. For compliancy with the masses and widespread distribution, compatibility will not be assured, but that's an unfortunate truth for all BD-R/RE disks anyway. Where we just want a disk for our own personal playback, it matters not of course, but the whole reason I use Blu-ray is for distribution, since for most home users, it's simpler and probably preferable to use one of the media players like the WD TV or Popcorn Hour, and the ever growing list of media players being spawned by the abysmal failure of Blu-ray to attract enthusiasts outside of people just using them to watch Hollywood commercial titles.

[Randall Leong]

Originally Posted by Chris Gotzinger

Okay, I checked again.

The warning reads:
"The overall bit rate for "video1" is greater than 28 Mbps. The overall bit rate is too high for burning Blu-ray onto a DVD."

It does sound a bit strange, but right below it leaves no question as to what media type I've selected:
"Estimated project size: 1923 MB (8.0% of 25,000 GB media)"

And I cannot click NEXT or FINISH because they're greyed out.

I re-checked this again, and discovered that the total size of your video file(s) is simply too small in size to be burnt onto a compliant Blu-Ray disc even with the higher 39 Mbps MPEG-2 bitrate. In my experience with DVDA I needed my videos to occupy at least 8.0 GB in post-authoring size in order to create a compliant Blu-Ray disc on single-layer 25GB media. Your total video files took up less than 2.0 GB, which is much too small for a compliant BD.

In other words, DVDA will not let you author a Blu-Ray disc whose total actual data size is less than the next-smaller project size (8.5GB, in this case). Sony just does not want you to leave 22GB worth of blank, unusable space on a BD-R. Therefore, the Blu-Ray project size should be set to the size that's closest to your particular video (in this case, 4.7GB--note that the "disc sizes" are the project sizes, not the type or capacity of the discs). Only after the disc creation is complete may you burn the image onto BD-R.

[Randall Leong]

Originally Posted by Tom Roper

I also found through trial and error, that the DVDA5 AVC video rendering although painfully slow and with not too many parameters to choose from, actually rendered with incredible quality, better than the encoders in Vegas, either the Mainconcept or Sony AVC. Although it is slow, and not too many adjustable parameters, there is one parameter that it does give you control over, the bit rate! It lets you choose whatever rate you want! I eventually settled for 18mbps, which meant AVCHD disks could play from regular DVD media in quite a few standalone blu-ray players.

{snip}

This was the best quality AVCHD method, better than mpeg-2, and better quality than the faster but poor quality low bitrate encoders in Vegas, (Mainconcept and Sony AVC).

Hope that helps. It's slow, but if you have the time for quality renders, it's better.

Tom,

I have used this encoder on several of my personal BD-R discs. I found that it works best if the videos to be (re)compressed were lossless or uncompressed AVI files or AVC/AVCHD videos. Transcoding an MPEG-2/HDV file to AVC using this encoder isn't quite as good as going from lossless/uncompressed or AVCHD to AVC, but still better than recompressing (as opposed to smart rendering) an MPEG-2/HDV file into another MPEG-2/HDV file.