I have a film I'm trying to put on VHX but it calls for a maximum bit rate of 13000. I'm using a quick time file with the DNxHD codec , because H264 causes color banding when I use it. The DNXHD works but does not let me adjust bit rate. Does anyone know how to do this?

DNxHD is a constant bit rate in one of a few flavours.  Depending on your frame rate you'll have access to different bit rates but you cannot adjust them from the available ones.  Generally the number after the letters (DNxHD185 etc.) refers to the data rate - in this case 185mbit/s.  That can't be adjusted.  If you need a different bitrate you need to use a different codec, not DNxHD.

Andi

Do not take this as gospel, but I remember either eading a EVS manual or speaking with a EVS rep at NAB and learning that you could in fact set a custom DNX capture rate in their application and that that was part of the SDK.  But that was a while ago and memory is a dangerous thing.

Don't know how you would confirm or deny my hazy memory.

Jef

EDIT:  OK. Found an EVS doc which seems to support my memory:

http://www.evs.com/sites/default/files/download_area/package/compatible_08.04.33/Multicam_08.04.33/DNxHD_Tech_Note_BST_070803.pdf

From this doc:

Though Avid DNxHD® is standardized at specific bitrates (120/185Mbps in “PAL” and 145/220Mbps in “NTSC”), Avid products can seamlessly read DNxHD® files and streams at other bitrates.  To allow users to determine the best balance betw een picture quality, storage capacity, number of video channels per server, and network speed, EVS XT [2] servers can generate Avid DNxHD® files and streams at any given bitrate between 20Mbps and 185Mbps. These files and streams remain perfectly compatible with Avid production tools.

It's likely the DNx codec does support a range of datarates the question then is how can you have control over that datarate? Without your own custome encoder I suspect you can't.

So it's a mute point.

But is a frame based codec the answer? 13mbps is very low for a frame based codec. even DNX14 if you could make it woudl look very poor.

You have to use a long GOP codec and H264 should give good results. H265 would give better.

I'm surprised H264 at 13Mbps looks poor. What are you using to encode the H264?

I'm exporting out of Avid MC5, as a quicktime file with H264 as the codec. and 13000 Kbits. Looks great but the banding around the colors totally wrecks the film

I'm using Avid MC5 to export out a quicktime file and using h264 as the codec at 13000 kbits.

Indyreel:

Looks great but the banding around the colors totally wrecks the film

These can't both be true.

13000 Kbits should be more than adequate for a decent h.264 encode -- but not the way you're doing it.  Quicktime uses an older, less efficient version of h.264 and is lugubriously slow.

Export from Avid same as source, or QTRef, or as DNxHD175 (depending on what your sources will allow) and then encode to h.264 with a better encoder like Squeeze or even handbrake -- as has been suggested in your other thread.

Even if you manage to hack the code to make a DNxHD 13 export, it will look awful as it uses a completely different compression scheme than AVC.