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Question about bitrate when exporting

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Melanie Easton
Question about bitrate when exporting
on Mar 30, 2016 at 11:19:17 pm


Quick question about bitrate when exporting in Premiere Pro.

I'm submitting a one minute film to a competition that has the following specifications:

Codecs: Apple Pro Res 422/4444 H.264 MOV
Resolution 1920 x 1080
Frame: 25p or 50i
Data Rate: up to 150Mbits/s.
Audio is stereo or surround sound 5.1.

This is all fine, but the "data rate up to 150Mbps" part kind of confused me.

I originally exported in H.264 using "Match sequence - high bitrate" and it gave me a bitrate of about 10Mbps. File size was about 72MB. This looked perfectly fine playing back on my computer, and a test run on a small cinema screen (maybe 2m high) also looked fine.

10Mbps seemed kind of small compared to "up to 150Mbps" so I did another export in H.264 using the "1080p HD 25p" setting, which gave me a bitrate of about 30Mbps and a file size of 228MB. Playback on my computer looked identical to the 10Mbps version.

Since this is for a competition, I'd like it to have the highest possible quality, but at the same time, the judges will be downloading the file to view it and 228MB might be a bit big for a one minute video? (We're in Australia and everyone has like, 1Mbps internet speeds so downloads can take forever.)

Do I go with the higher bitrate or will it not really make a difference in quality? When would you ever have a 150Mbps bitrate? That seems really high if the standard for 1080p HD is only around 10-20Mbps (according to my Google search)?

If anyone can clarify, that would be greatly appreciated.

Thank you!!

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Vince Becquiot
Re: Question about bitrate when exporting
on Mar 31, 2016 at 2:03:15 am

Hi Melanie,

There really is no standard when it comes to bitrates. With H.264 can get away with lower rates. BluRay, for example, is usually around 40Mb/s (H.264), so that's a good reference point for "Hollywood" HD quality. If you have a lot of noise in your movie, then it will require a higher bit rate or you will start seeing artifacts. Lots of motion, rushes, shaky cameras all require more data to look good since compression depends on changing pixels from frame to frame. Raise the brightness on your monitor and look at your backgrounds/dark areas, that's usually where artifacts will pop up.

Prores varies between 70 and 150 Mb/s depending on the format you pick, you won't have control over the bit rate.

Vince Becquiot

Indigo Live | Kaptis Media

San Francisco Bay Area

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Chris Wright
Re: Question about bitrate when exporting
on Mar 31, 2016 at 3:46:28 am

if its being judged, are they downloading it first or or are streaming it? you better find that out. if its a simple streaming link, your video may go viral a lot easier than if you have a hidden download link somewhere on a ftp server.

just a thought if they are all being streamed. (i don't know)
every second it takes downloading actually looks less professional in the streaming universe. in youtube, you can instantly stream 720 HD -1080p video for example. h.264 is your friend and can look quite nice as you've seen. " test run on a small cinema screen (maybe 2m high) also looked fine. " that says its all to me. you've already tested it, you're way above your peers in that regard. the colors should look good on a similar playback device.

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Melanie Easton
Re: Question about bitrate when exporting
on Mar 31, 2016 at 6:41:45 am

Thanks so much for the advice!

The competition has requested it be submitted via "a downloadable secure private link to a file sharing service. Must be password protected." so I figured I'll Dropbox it to them. (In which case they could also stream it if they wanted to, but I'm assuming they're planning to download it so they can watch all the entries at once.)

It's a documentary so there is a lot of movement and shaky camera work in certain sections - would probably be worth it to go for the higher bitrate in that case.

If I post it online for public viewing after the competition ends, I'll export in a lower bitrate for Vimeo/Youtube purposes.

Thanks again!! :)

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