Blu-ray bitrates?

Yep wrote on 2/22/2015, 5:41 PM

Using Sony Vegas Pro 13 I created a Sony AVC/MVC file for a DVD Architect blu-ray project.

The original footage had a bitrate of 29 Mbps, so in Vegas Pro I output to the AVC file at the same bitrate.

I imported the file to DVD Architect and set the Blu-ray bitrate in the properties dialog to 30 Mbps. When I examined the resulting Blu-ray stream for that clip I discovered DVD Architect had reduced the bitrate to just a tad over 22 Mbps.

That surprised me - I had thought the Blu-ray stream would be the full 29 Mbps. So I'm just wondering if I'm doing something wrong or if that is the way it should be.

Comments would be appreciated.

Comments

PeterDuke wrote on 2/22/2015, 8:41 PM

If you choose a Blu-ray template in Vegas and export the video, and then choose the AC3 Pro template and export the audio (same file name stem), then DVDA will not re-encode either your video or audio.

Yep wrote on 2/23/2015, 12:36 AM

Thanks for the reply Peter. I just made a small test clip to try that out.

The render templates I used were:

Audio: Dolby Digital AC-3 Pro, =Stereo DVD
Video: Sony AVC/MVC (*.mp4;*m2ts;*avc), Bluray 1920x1080-60i, 29 Mbps video stream

In DVD Architect I made the following settings:

Video format - AVC
Bitrate Mbps - 40.00
Resolution - 1920x1080
Frame Rate - 29.97 Interlaced

Audio ormat - AC-3 Stereo
Bit rate (Kbps) - 448

Using those settings I get the same results that I got before. A Blu-ray stream with a bit rate of total bitrate of 22.387 Mbps.

PeterDuke wrote on 2/23/2015, 2:32 AM

The Sony AVC/MVC encoder in Vegas is limited to 21,999,616 bps. You can set it higher but it resets itself to that value before rendering.

Yep wrote on 2/23/2015, 4:08 AM

Ah-hahhh!!! OK - ran the test again using Main Concept AVC and the Blu-ray stream came out at just over 30 Mbps.

It seems a bit ridiculous that Sony AVC/MVC allows you to set a higher bitrate if it's going to reset itself regardless.

Not to worry - worse things happen at sea :)

Many thanks Peter for taking the time to educate me.

PeterDuke wrote on 2/23/2015, 7:06 AM

We learn from each other. :)

videoITguy wrote on 2/23/2015, 7:32 PM

Yep - the AVC encoder is meant to be more bit-rate efficient - but you get the best quality from the best of sources with a higher bit rate encoder. Choose your weapon and go forth.