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H.264 settings for TV Broadcast

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Sarah Kali
H.264 settings for TV Broadcast
on May 17, 2008 at 5:32:44 am

Hello,

I am sending over the internet a 30sec TVC to a company that will distribute it to the TV networks. They have asked for H.264.

I have made the highest quality H.264 file I could in compressor (I am running the latest compressor)

The file ended up having a data rate of 8mbs, and being about 60 mb in size (the TVC is a mixture of Full screen talking heads filmed against a fairly plain backgrop dissolving with 12 frame dissolves to titles on a solid background - so not a lot of movement etc to compress in the footage)

I was surprised by the small file size and data rate. Am I missing something in the settings?

Resolution is Anamorphic 16:9, 720 x 576 (PAL),
I used the variable bit rate encoding setting set to the highest quality,
Key frame was set to every 25 frames (source footage is 25fps)
Audio is PCM, 48 kHz stereo.

Should I instead use the setting where I can set the data rate rather than the best quality setting. If so what data rate setting to you recommend.

Is there anything else I can do to up the quality?

It's a FCP DV project exported to QT None Compression intermediate file before being taken in to Compressor.

You comments would be very much appreciated.

Best Regards,

Sarah


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Daniel Low
Re: H.264 settings for TV Broadcast
on May 17, 2008 at 6:59:25 pm

8Mb/s should provide a very high quality standard def H.264 clip. If you look on the Apple movie trailers website even the HD 720p trailers are between 5-7Mb/s. If you are happy with the quality then there shouldn't be a problem (does it look as good, if not exactly the same as the source?

However exporting out of FCP as uncompressed is pointless. My preference is to export out of FCP as a reference clip (non-self contained) as you will then be exporting at exactly the same quality as the source DV material.





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Sarah Kali
Re: H.264 settings for TV Broadcast
on May 17, 2008 at 10:38:58 pm

Daniel,

Thank you for your reply. Data Rate info very helpful.

I have always used None compression as the intermediate file when enoding to MPEG2 because MPEG2 hates DV and the graphics look markedly worse for wear when you go from DV to MPEG2.

I've carried this idea on to to creating the H.264 but from what you say - not neccessary. I will run some tests using a reference file.

Thanks for the info, very much appreciated.

Sarah



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Daniel Low
Re: H.264 settings for TV Broadcast
on May 18, 2008 at 11:44:17 am

By exporting to uncompressed all you are doing is 'padding' the file, you are not in anyway improving the quality.

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Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


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Craig Seeman
Re: H.264 settings for TV Broadcast
on May 19, 2008 at 8:09:27 pm

I can see a reason for doing a final render of FX and titles in an uncompressed codec or other "higher" codec (Apple Pro Res). While it won't improve the source files it can keep the titles and graphics from taking that "DV" codec hit.



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Daniel Low
Re: H.264 settings for TV Broadcast
on May 19, 2008 at 9:48:36 pm

Fair point-I should have given that some thought, it's been while since I've been in DV land.


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Craig Seeman
Re: H.264 settings for TV Broadcast
on May 19, 2008 at 8:17:45 pm

DGFastchannel here in "the State" asks for 18mbps MPEG2 Program Streams for TV spots. Did they give you a data rate for H264? Apparently not. You might ask them if they have a minimum and maximum.

BTW I'm doing "digital signage" spots at the moment and the digital signage company hasn't given me data rate specs either. I wonder if this is a new trend.

You could always "turn it up to 11" and see if their system blows up. I sent in an H264 encode at 35mbps (720p30 - they're all HD) to see if I've pushed their limit.



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Devin Crane
Re: H.264 settings for TV Broadcast
on May 19, 2008 at 10:44:07 pm

With H.264 the data rates don't need to be very high. 1.5mb/s is almost equivalent to DVD quality. 8mb/s is high enough for HD to be delivered over the internet and still looks pristine, so sending 8mb/s SD should be fine.



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