dvd-hq.info

[Tafflad]

Hi ... trying to get VideoRate correct for creation of a DVD, and was referred to the calculator on http://dvd-hq.info/bitrate_calculator.php and it said post any Q's here.

I input my basic figures .... 80 min duration.
Audio set at 320 Kb as it will be AC3 and rate is fixed at that in my render template.
For VBR gave me 9200 peak, 7100 average and 2800 minimum

I put theses VBR rate numbers into Sony Movie Studio and Rendered MainConcept PAL DVD - single movie no menus .... render files produced, but when I load into DVD architect to create .. it tells me files are 109% over size at 5.18GB? ... yet had put standard 4.7GB media into calculator ?

Do I need to select something other than 4.7GB

This is 'warning screen' I get when I try to burn DVD:

[img]http://tinyurl.com/nt47fty[/img]

[RMN]

As you can check by doing the maths:

80 min. x 60 = 4800 seconds

4800 sec. x 320 kb/s = 1536000 kb = 192 MB (183 MiB)
4800 sec. x 7100 kb/s = 34080000 kb = 4.26 GB (3.967 GiB)

Total: 4.452 GB (4.15 GiB)

The calculator actually gives you a slightly higher value for the video (4160 MiB) because it already includes a small safety margin due to some encoders not respecting the user-selected average.

So if your authoring programs says it adds up to 5.18 GB, either it's adding some files to the encoder's output, or the encoder itself didn't respect the bitrates you selected.

I know that some authoring programs include their default menus on the disc even if you say you don't want them, but the difference seems kind of big for that, so my guess would be that the encoder is not respecting your average.

If you can, try creating two separate files, one just with the audio and the other just with the video. Compare their sizes with the sizes predicted by the calculator. If they match, it means your authoring program is adding extra files (ex., menus). If one of them doesn't match (ex., the video file is larger than predicted), that means the encoder is not respecting the bitrates you selected. Note that Windows shows file sizes in GiB / MiB (factor of 1024), not in "real" GB / MB (factor of 1000).

You have two ways to deal with that:

a) Calculate the ratio of the error (by dividing the predicted file size by the file size produced by your encoder) and multiply that by the bitrate recommended by the calculator (i.e., if the predicted file size is 10% lower than your encoder's actual output, multiply the suggested average bitrate by 0.9 before entering it into your encoder).

b) Enter the difference between the disc size and the resulting project size into the "other assets" field of the calculator. This will make the calculator reduce the video bitrate(s), and hopefully that will be enough to balance the error in the encoder's average.

RMN
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[Tafflad]

I took a slightly alternate approach.

I used same Render template .. but chose 'video' only and set for Elementary Streams.
Used the VBR settings in the calculator.
Then a separate Render using Dolby AC3 template for audio

The again tried DVD Architect and it worked fine .... so something amiss somewhere, but at least I have a solution.

[RMN]

So when you render the audio and video separately, the file sizes match the expected sizes?

What was your compressor rendering in your first attempt? A single MPEG-2 file with embedded AC3 audio?

RMN
~~~

[Tafflad]

[RMN]

Ah, that was probably the problem, then. You effectively had two audio steams, one in MPA (that came with the video) and one in AC3 (in the separate file), and the authoring program was probably trying to keep both.

RMN
~~~