How much time on Blu-ray 25GB

[Scott Brooks]

I've been to a couple of Blu-ray sites and sales sites, but I can't find the answer. I would like to offer some of my stage events on Blu-ray was well as DVD, but I can't find any information as to how many hours of HD footage I can get on a 25GB disk.

I've seen a couple of sites that simply say, over two hours of HD video on a 25GB disk and up to 9 hours on a 50GB.

"Over two hours" doesn't tell me as much as I need to know. Many of my productions run 2 1/2 hours ... some a little more and some just a bit longer than two hours.

The price difference between 25gb and 50gb seems to be substantial, so I need to make sure I know what I'm getting in to.

Thanks -

Scott

[Monday Isa]

My phone app is saying 2hrs 30mins at 22mbs compression. Image attached.

[Dave Partington]

Take a sample of one of your videos and compress it for H264 and see how low a bit rate you need to make it fit. BD isn't actually 25GB, it's really 23.9GB or something like that - I don't remember exactly.

So, once you've figured out how low you need to go on the bit rate, make yourself an H264 sample file (it doesn't have to be 2.5 hours - just export a couple of minutes) and play back on your screen to see how you like it.

I've made a BD with a bit rate as low at 15mbit to fit more on (sorry, can't remember the length now) and it looked fine - still 10 times better than DVDs!

[Scott Brooks]

That sounds good. I don't even have a burner yet. I just figured that I'd pick one up in the next couple of weeks to see what I could reasonably provide.

[Dave Blackhurst]

Keep in mind that frame rate (24p files will be smaller than 60i files from my experience), and bitrates will affect the total file size (I used to burn BR format onto DVD rendered @ 17Mbps which was the max bitrate for that format IIRC... BR can go up to 25Mbps IIRC...). Don't quote me on those numbers, as I don't keep them "handy", but I think they are correct!


As the other Dave said, you can experiment with bitrates to balance quality and file size, meaning the question of "how much time" can vary greatly - high bitrate/high quality means larger files and shorter total "time" that can be stored on a disk... Keep that in mind as you fiddle with whether you can "fit" the desired files onto the burned disk or not, and try to strike a balance between quality and file size.

Hopefully that muddies the waters sufficiently for you <wink>! Keep in mind that when a manufacturer uses the phrase "up to" or "over"... they are probably NOT quoting max quality images/files, so take those sorts of marketing terms with a bit of skepticism!

[Tim Bakland]

When clients have asked for all the "running footage" (full ceremony as well as highlights), I've sometimes pushed 2:45:00 and then pulled the bitrate down to 18mbps and found that it still looked great (and fit).

And when you're more around the 2hour range, you can be up in the 20's for mbps.

I bought a spool of 50GBs once, and just didn't find the investment worth it. I rarely go much beyond 2hours and, when I did, found the lower bitrate totally respectable for event videography.

[Jeff Pulera]

Hi Scott,

Here's a link to a bitrate calculator - DVD-HQ : Bitrate & GOP calculator

I believe the default audio bitrate for Blu-ray is 384 for purposes of plugging into the calc, don't have access to my encoder right now to look.

As an example, 2.5 hours (150 minutes) comes up with a recommendation of 20700. Usually a good idea to go a bit lower for safety, to allow for menu overhead and such. Motion menus will further lower the number since they take up additional space. If I have 5 minutes of motion menus (5 menus of 1 minute each), then I add 5 minutes to the video length when calculating.

So maybe use 19700 or 20000 (19.7 or 20) for instance. What you don't want to have happen is that you spend hours encoding only to end up with a file just a tiny bit too big for the disc and then you have to start all over!

What software do you use? From Adobe Premiere, Dynamic Link to Encore will automatically adjust the encoding to fit, but many users don't like DL, myself included, and will use Adobe Media Encoder to manually create the assets for DVD and Blu-ray.

For Blu-ray, you will have a choice of MPEG-2 or H.264 encoding. For short projects (at high data rate) an MPEG-2 file can look as good as H.264, but for longer videos at lower bitrates, then H.264 has the definite advantage since it is a much more efficient codec.

Thanks

[Scott Brooks]

I really appreciate the responses here. When it comes to bit rates and things like that ... I'm LOST ... really lost.

I edit with FCPX and right now I'm shooting at 1080 60i with a Sony ax2000 and Canon xa10. I'm seriously considering getting rid of the Sony and going with an xa20 (even though I don't like the menu system).

I can use the "share" feature in FCPX to go to h.264 within the system, but if I need to change settings then I think I have to take it to Compressor.

As long as I've been shooting video, no one has ever asked for anything in HD. This is more than likely nothing more than a vanity thing ... wanting to finally see what my work looks like in better quality from something other than my computer. On the other hand, if I offer it then maybe someone will bite.

[Dave Partington]

Originally Posted by Scott Brooks

I edit with FCPX and right now I'm shooting at 1080 60i with a Sony ax2000 and Canon xa10. I'm seriously considering getting rid of the Sony and going with an xa20 (even though I don't like the menu system).

I can use the "share" feature in FCPX to go to h.264 within the system, but if I need to change settings then I think I have to take it to Compressor.

Making the required presets in compressor and having them available in FCPX is trivial, and hopefully you know that you can easily set the bit rate and easily see the file size it's going to produce.

BTW - I always export a ProRes file from FCPX first as my master file and 'then' retarget that to what ever I need in other codecs in Compressor or Media Encoder. YMMV.