Mbs to Mbps in H.264

[Ken S.]

A local TV station requires HD H.264 in 50Mbs. How does that translate to Mbps in media encoder, exporting with premiere pro? The H.264 has a max setting of 20Mbps.

[Ivan Myles]

Increase the Level and change the Profile as required. Max bitrate for [email protected] is 300mbps. I recommended getting a full list of specs from the station with all their requirements.

[Ryan Holmes]

Do you mean 50MB or 50Mb? Mbs and Mbps (or Mb/s) are really the same thing.

MB = Megabyte
Mb = Megabit

50Mb/s = 6.25 MB/s
50MB/s = 400Mb/s

So we need to be clear what you are looking for here. I’d guess 50Mb/s (megabits) is what you’re looking for. In order to encode higher data rates using h.264 you have to increase the “level” you’re encoding at. It’s a drop down menu beneath “Profile.” To go over 20 Mb/s you need to start at level 4.1. Level 5.1 can encode at data rates up to 240 Mb/s. This Wikipedia chart is a handy reference: https://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Levels

You need to use level 4.1, 4.2, 5, or 5.1 in order to achieve the data rates necessary.

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost

[Ken S.]

Thanks for the info guys. Ryan this is what they sent me. This is recommended and not necessarily a fixed requirement.

For HD (High Definition) files:
Bit Rate: 50Mbs
Resolution: 1920x1080i, Interlaced
Frame Rate: 29.97fps (constant)
Recommended Codec: H.264
Audio: Stereo/48Khz

This is a small project and I will be shooting AVCHD 24mbps. I am not sure if it makes sense to output at twice the bit rate of what I am recording! Will there be any quality difference, or should I just output at 24mbps, which is what the camera records.

[Ryan Holmes]

If that is the station’s requirement you give them exactly what they request. You won’t be increasing quality at all since you shot 24Mbps, but you will be conforming to their requirements. If you do something other than what they’ve specified, they’ll likely reject your content for failure to adhere to standards.

So in this case, it’s best to follow their guidelines and give them what they’re requesting. And it’s very easy using Media Encoder.

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost

[Ken S.]

will do, thanks.