what is safe max bitrate for AVC (mp4) BD

[Marius Boruch]

The template says 15MBs but what is safe max bitrate for AVC (mp4) BD so the BD will not freeze or stutter? Can we compress using more than 15Mbs???
I had some problems with 25Mbs MPEG2 BD discs - they were freezing.

[Danny O'Neill]

15mbps AVC is far superior to any bitrate of MPEG2. The default 15 is perfect, no need to go higher.

However AVC and DVD architect have issues and you will no doubt get an error when preparing the blu-ray, you need to re-compress the vid in DVDA due to this 'feature'. Sony are aware and have been fixing it for the past year.

[Marius Boruch]

so what do you suggest? edit in Vegas compress to (what???) and then export the file to DVDA to compress to AVC.

[Randall Leong]

Originally Posted by Danny O'Neill

15mbps AVC is far superior to any bitrate of MPEG2. The default 15 is perfect, no need to go higher.

However AVC and DVD architect have issues and you will no doubt get an error when preparing the blu-ray, you need to re-compress the vid in DVDA due to this 'feature'. Sony are aware and have been fixing it for the past year.

Actually, this happens only if you render the AVC in Vegas with any chapter markers in the Vegas project. Rendering to AVC in Vegas will embed the chapter markers inside the actual video file - and those chapter markers turned out to be incompatible with the smart renderer in DVDA. There are two workarounds to this problem: One is the recompress method in DVDA as other posters mentioned; the second would be to re-render the AVC file in Vegas without any chapter markers, and then add the chapter markers after you add the AVC footage to your DVDA project.

One more thing: In order for the second workaround to work properly, the Sony AVC encoder must be used (using either the AVCHD or Blu-Ray AVC presets; the former renders embedded audio which itself must be recompressed even if the video doesn't get recompressed while the latter requires the rendering of a separate audio stream). Any AVC video rendered with the MainConcept AVC encoder that's included in Vegas will require recompression since the resulting files would be neither AVCHD nor Blu-Ray compliant. MainConcept does sell an AVC reference encoder which is Blu-Ray compliant, but Vegas still includes an older version of the MainConcept encoder which is really meant to produce low-definition AVC files for portable media devices.

All of the above assumes that you have the most recent release of Vegas Pro, 9.0c and DVDA 5.0b.

By the way, although the MainConcept MPEG-2 encoder included in Vegas produces Blu-Ray compliant streams, MPEG-2 itself is relatively ill-suited for HD footage because it requires relatively high bitrates to minimize the loss of image quality. In fact, it really requires bitrates well above 30 Mbps in order to minimize such losses with anything above standard definition. This is why MPEG-2 HD at a given overall video bitrate only equals Blu-Ray AVC at about 40% of the overall video bitrate in terms of image quality (or put it this way, 25 Mbps Blu-Ray MPEG2 roughly equals 10 Mbps Blu-Ray AVC).

To Marius:

You probably might not know this, but have you ever considered the possibility that the quality of the discs that you use to burn the videos onto for yourself and your clients might be suspect (which brand, speed rating and type of discs were you using?) or burned at too high of a speed or their standalone players might be either very picky or not fully compatible with burned BD media? Not all Blu-Ray players can play back burned media. And if you were using the relatively new and cheaper LTH BD discs, even fewer players and burners support this type unless their firmware is updated. (These are the exact same questions I would ask if I receive burned BD discs which stutter or freeze on my standalone Sony Blu-Ray player even at modest bitrates.)

And the biggest reason why I asked which brand of BD-Rs that you were using is because there are some brands which purchase media from suspect manufacturers or sources.

[Marius Boruch]

thanks Randall,
The reason I asked is because I noticed quite a bit loss of quality btwn. original footage and then distributed on BD in mpeg4 (14-16Mbs). Is this normal??
I use mostly VErbatim's and Memorex; any suggestions based on your experience with media brands and "good" retailers???

For Randall: I am in Chicagoland too.

[Randall Leong]

Marius,

The Verbatims are reasonably good - but chances are that you might have simply burnt them at MAX speed when that speed is two or four times as fast as the rated speed of the media itself.

The Memorex BD-Rs, on the other hand, are mostly rebranded Ritek (RiData) BD-Rs. Ritek's BD-Rs, especially its 2x rated ones, have had extremely erratic quality control: The good ones are reasonably reliable, while the bad ones deteriorate at a much faster rate than normal in storage.

In addition, the built-in burning engine in DVDA is simply not very good at writing to Blu-Ray or AVCHD disc. That's no surprise since DVDA was originally an SD DVD authoring program which has had BD authoring capabilities slapped on. I would use it only to create disc images on the hard drive so that another burning software program which supports writing from ISO images such as ImgBurn (a free download) can perform the actual burn to disc.

Finally, the quality loss is, indeed, due to the multiple transcodes and recompression. Your EX1 originals were in HDV to begin with, then transcoded to AVC in Vegas, and then recompressed again in DVDA. All that degrades image quality. I would instead render your HDV originals out to a lossless AVI codec such as Lagarith before transcoding to AVC to minimize this loss. The Sony YUV codec is also workable, but it's merely a "mostly lossless" codec operating in a 4:2:2 color space (unlike Lagarith which operates in a 4:4:4 RGB color space by default).

[Bruce Phung]

Randall, I got a question for you. Do you recommand deinterlace the video first before render and burn avchd/bd dis? or don't matter.


PS. just leave it UFF?

[Marius Boruch]

how to install and use Logarith???

[Randall Leong]

Originally Posted by Bruce Phung

Randall, I got a question for you. Do you recommand deinterlace the video first before render and burn avchd/bd dis? or don't matter.


PS. just leave it UFF?

If you're not going to resize (change the resolution) of the video, it's best to leave native 1080/60i footage as interlaced. Always leave 1080/60i footage as UFF (or TFF); any 1080/60i footage that's LFF/BFF is considered "nonstandard" and should be converted to UFF/TFF using the "Field Delay" filter in VirtualDub or something similar. Interpolating this footage to 1080/24p will reduce image quality. However, if your "1080/60i" video is really 1080/24p encoded inside a 1080/60i stream, you will need to inverse telecine (IVTC) this footage to bring the footage back to 1080/24p.

As for 1080/60i video deinterlaced to 1080/30p, I would not currently recommend this. This is because neither Blu-Ray nor AVCHD DVD officially supports 1080-line progressive video at frame rates higher than 25 fps. If you deinterlace to 1080/30p, you would have to convert it back to 1080/60i before you author this video onto BD or AVCHD DVD, and then you would lose temporal resolution in the process.

[Randall Leong]

Originally Posted by Marius Boruch

how to install and use Logarith???

I think you download an already compiled installer (yes, the Lagarith home page provides a link to already compiled Lagarith installers for 32- and 64-bit Windows) and then run the setup program of that installer. The choice between the 32-bit and the 64-bit installer depends on whether you are running a 32-bit or a 64-bit edition of Windows. The two alternatives are the manual installation option (which requires you to be familiar with finding the correct folders to copy the correct DLLs to) and the "source code" version (which requires a special compiler such as Microsoft Visual Studio; the Express version is a free download from Microsoft, while the full-featured version is only available for purchase).