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h.264 data rate question for SD video

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Allan Hughes
h.264 data rate question for SD video
on Jun 12, 2012 at 3:03:24 pm

I'm exporting SD video for exhibition on media player. The media player can handle rates of 25Mbits/s. I made an export out of FCP via Quicktime Conversion to mpeg-4 (h.264 option) and set my data rate to 24000 kbits/sec. The conversion ran through but came out with only 9.3 Mbit/s data rate. Does QT cap the data rate for SD? I'd like to get the best possible quality export for the player (Roku Brightsign).


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Brad Elliott
Re: h.264 data rate question for SD video
on Jun 14, 2012 at 8:59:57 pm

If you select automatic for data rate and best/2 pass you will get the highest possible quality/data rate for an H264 file.

I believe QT is limiting the data rate for the SD file as 24MB for a SD file seems like a lot of overkill to me and turning up the data rate after a certain point cannot improve SD.

The suggested 25MB rate for the box is most likely for HD H264 files. I would be surprised if someone could tell the difference between an HD H264 at 12MB or 18MB in QT. Possibly the Roku is doing something to the file for playback but it seems unlikely.



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Allan Hughes
Re: h.264 data rate question for SD video
on Jun 18, 2012 at 11:14:35 am

OK that's good to know. I made another export through Compressor to h.264 QT and using similar rates came out with an average of 14MB/s.
Think the Roku will oversample, but only in certain circumstances depending on the cable and device it's connected to.


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