Bitrate - 18Mbps or 25Mbps for HDV?

[Nicholas de Kock]

I'm preparing my first Blu-ray disc with Sony DVDA 5, the default template sets the bitrate to 18Mbps, HDV is 25Mbps, will I encounter any playback problems if I use 25Mbps?

[Jeff Pulera]

Are you encoding to H.264 or MPEG-2 for Blu-ray? Bit for bit, H.264 is more efficient than MPEG-2, meaning that at the same data rate, H.264 offers superior quality. At lower data rates, the difference will be very noticeable, while at high data rates, MPEG-2 can look excellent and the H.264 advantage is somewhat lost (H.264 takes much longer to encode, so is it worth the time??).

The Blu-ray spec will handle up to 40Mbps, so don't be afraid to crank up the data rate if you have room (the program is not too long to fit the disc at the chosen data rate). Keep in mind the law of diminishing returns though, will anyone notice a quality difference between H.264 at 20Mbps vs. 30Mbps?

Back to the original question, no playback problems at 25Mbps, perfectly safe.

Get yourself a ReWritable Blu-ray blank and encode some short samples using both MPEG-2 and H.264 at various rates and make your own visual tests to see how you want to proceed.

Jeff Pulera
Safe Harbor Computers

Originally Posted by Nicholas de Kock

I'm preparing my first Blu-ray disc with Sony DVDA 5, the default template sets the bitrate to 18Mbps, HDV is 25Mbps, will I encounter any playback problems if I use 25Mbps?

[Nicholas de Kock]

Jeff thank you for response! I'm currently encoding to MPEG-2 (quite happy with reduced encoding time), that's why 18Mbps seemed rather low. I actually don't have a BD burner at the moment so can't do any of my own tests however have been editing/rendering/storing all my projects in HD for the last year, I want to prepair my projects for Blu-ray now so that when I get a burner and find some thermal printable discs that I can send them out.

[Taky Cheung]

Bluray burners are relative inexpensive these days.

Newegg.com - LG Black 6X BD-R 2X BD-RE 16X DVD+R 6X BD-ROM 4MB Cache SATA Internal Blu-ray Burner 6X Blu-ray Disc Burner & HD DVD-ROM Drive Model GGW-H20L - Blu-Ray Burners

I paid $340 for this thing a little over 1.5 yrs ago.

[Peter Axford]

At 18Mbps I would forget about MPEG2 and use AVC. Also note that if you are using HDV1080i it is 1440*1080 - a resolution that is only supported using AVC on BD. If you used MPEG2 you would have to upscale to 1920*1080 or go down to 1280*720. Have a look at Blu-ray Disc - Wikipedia, the free encyclopedia for supported formats. Hope this helps.

[Taky Cheung]

Originally Posted by Peter Axford

At 18Mbps I would forget about MPEG2 and use AVC. Also note that if you are using HDV1080i it is 1440*1080 - a resolution that is only supported using AVC on BD. If you used MPEG2 you would have to upscale to 1920*1080 or go down to 1280*720. Have a look at Blu-ray Disc - Wikipedia, the free encyclopedia for supported formats. Hope this helps.

That is incorrect. HDV is 1440x1080. You can author 1440x1080 Bluray with either MPEG-2 codec or H.264 codec.

[Prech Marton]

you CAN, just the disc wont be a STANDARD Blu-ray disc.
of course many player will read and display fine.

[Randall Leong]

Originally Posted by Nicholas de Kock

Jeff thank you for response! I'm currently encoding to MPEG-2 (quite happy with reduced encoding time), that's why 18Mbps seemed rather low. I actually don't have a BD burner at the moment so can't do any of my own tests however have been editing/rendering/storing all my projects in HD for the last year, I want to prepair my projects for Blu-ray now so that when I get a burner and find some thermal printable discs that I can send them out.

If you left DVDA5 Pro at the default Blu-Ray settings (MPEG2, 18 Mbps), and you left your HDV files at 25 Mbps, then what DVDA5 Pro does is render the menus at 18 Mbps while leaving your HDV video untouched. This is because DVDA does not recompress video that's already compliant with the disc format (this means MPEG2 HD video clips with an average video bitrate of up to 28 Mbps) unless you force it to. (And speaking of video recompression in DVD Architect, the program is not good at recompressing to MPEG2 while its AVC recompression is IMHO superior to either of the AVC encoders that are in Vegas itself.)

And as the previous poster stated, it would be best to convert 1440x1080i HDV files to the 1920x1080i Blu-Ray MPEG2 format in the main Vegas program if you want self-mastered MPEG2 Blu-Ray discs that meet the official Blu-Ray standards. With the Blu-Ray template, only the video gets rendered, so you must also render the audio separately. Use the AC3 Pro encoder to render out the audio, using the "Default" template (with HDV-embedded audio, it's typically stereo, 48 kHz sampling rate and 384 Kbps--you should change the audio bitrate in the custom settings to 384 kbps since the default audio bitrate in stereo projects is only 192 kbps). If you forget this and used the AC3 Studio encoder, DVDA Pro will always recompress the audio if your project is a Blu-Ray project since the AC3 Studio encoder is meant to be used with DVD Architect Studio, whose most recent version still supports only standard-definition videos.

[Tom Roper]

Taky is correct. 1440x1080 is a supported resolution of Blu-ray, does not need nor benefit from upscaling to 1920x1080.

http://www.blu-raydisc.com/Assets/Do...2955-15269.pdf

[Randall Leong]

Originally Posted by Tom Roper

Taky is correct. 1440x1080 is a supported resolution of Blu-ray, does not need nor benefit from upscaling to 1920x1080.

http://www.blu-raydisc.com/Assets/Do...2955-15269.pdf

That's true, but only if that 1440x1080 video is encoded with the AVC or VC-1 codec. MPEG-2 video at 1440x1080 is not officially supported; it should be either transcoded to AVC or VC-1 or upconverted to 1920x1080 in order for the finished product to fully meet Blu-Ray Association specs.

In other words, unmodified 1440x1080 HDV (which uses the MPEG-2 codec) authored onto Blu-Ray disc is considered "nonstandard", which means that some Blu-Ray players will choke on such a disc even if they support BD-R or BD-RE media.

[Tom Roper]

Originally Posted by Randall Leong

That's true, but only if that 1440x1080 video is encoded with the AVC or VC-1 codec. MPEG-2 video at 1440x1080 is not officially supported; it should be either transcoded to AVC or VC-1 or upconverted to 1920x1080 in order for the finished product to fully meet Blu-Ray Association specs.

In other words, unmodified 1440x1080 HDV (which uses the MPEG-2 codec) authored onto Blu-Ray disc is considered "nonstandard", which means that some Blu-Ray players will choke on such a disc even if they support BD-R or BD-RE media.

Sorry but that is also wrong. The document I linked was old, dated 2005, but the Blu-ray spec was subsequently changed to include 1440x1080 mpeg-2. I don't have a more updated link, but it has been confirmed previously.

Some Blu-ray players will not play BD-R/RE, no matter it is encoded with. That's just a sad fact of Blu-ray.

[Randall Leong]

Oh, I see that the info has not been updated as frequently as I would have liked.

At one point, the official Blu-Ray spec also listed 1280x720p at 50 fps (PAL) or 59.94 fps (NTSC). If I went with the often-futzed-with info on Wikipedia, those frame rates would have been no longer supported--this would have limited all progressive-scan video frame rate support to a low 25 fps (PAL) or 23.976 fps (NTSC).

[Nick Hope]

Originally Posted by Tom Roper

Sorry but that is also wrong. The document I linked was old, dated 2005, but the Blu-ray spec was subsequently changed to include 1440x1080 mpeg-2. I don't have a more updated link, but it has been confirmed previously.

I was also going by the March 2005 un-finalized document, as summarised on the Wikipedia page, but I was puzzled why Sony DVDA and TMPGEnc Authoring Works are both letting me create Blu-rays of 1440x1080 MPEG-2 material (from HDV) without giving me any warnings about non-compliance (and incidentally I've sold a few and no complaints). So I did some digging and found this updated specification. On page 15 there is no restriction on this resolution, as there had been in the draft white paper.

I will change the Wikipedia page as I am sure it is confusing many people.

[Randall Leong]

Thanks for the update, Nick.

Still, it does not change the fact that 25p and 30p are still not supported in Blu-ray at any resolution. At present, for optimal playback results, 25p and 30p have to be converted to 50i and 59.94i (or 50p and 59.94p at 1280x720), respectively, before being authored onto disc.