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H264 compression requirement
I have a client that wants a video delivered with the following specs.
H.264 / 720×486 29.97
Interlaced
20Mbs
Audio: 24bit Stereo 48k (Little Indian)This original video is 1920x 1080 using XDCM EX 1080I60 (35Mb/s VBR) Integer (Little Endian)
When I use QT Pro to convert the file, I don’t have the option to do 24bit, the lowest rate available audio bit rate is 64, but I always use 128 for better quality. Also, I don’t have the option to do Little Endian, but I do ACC. I don’t usually down convert to SD as this client is asking, but shouldn’t I de-interlace the video? just to confirm since they are asking for 20Mbs I assume I do 20,000 kbits in the data rate box?
I appreciate any help that’s given.
Thanks.
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7 Replies
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The audio you are referring to is Master quality audio. 24 bit depth, (twice the bit depth in a usual CD/DVD quality of 16 bits,) is VASTLY different than the “bitrate” of 128kbps that you are looking at. To my understanding, h.264 does not even carry 24 bit audio (I could be wrong).
16 Bit audio (CD/DVD quality) has a bitrate of 1,411,200 bps, or ~1400kbps. The closest you can come in an mp3/mp4 file is 320 kbps. Note that this is not even HALF of CD quality.
So, your client (at least according to the specs you listed) is not asking for really LOW quality audio, they are asking for the absolute HIGHEST quality. Does that make sense?
………As far as why they need/want SD video from an HD source, especially with such a high bitrate of 20Mbps, is beyond me…..
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They also don’t mention whether they want it anamorphic, letterbox, or center cut. Why would they want it interlaced unless they’re going back out to a television in some way? You now have permission to ask your client some questions.
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they are going to send this to TV stations, so I understand the reason for the high rate, but I don’t know how to make a 24bit audio file in H264. Thanks for the info.
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Interesting that they’re sending something to Broadcast as H.264 in the first place, why you would do that I don’t know.
“Where that light source is coming from?”
“The same place as the music.” -
At KTVT we get h264 files as a general rule. And we also send out h264 to other stations. I would leave it interlaced..upper for HD lower for SD.
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Thanks for all the info. They need H264 because we are shooting in a small town in the middle of Michigan and we have to send this video to TV stations all over the Midwest. We’re shooting in HD but could never upload a full res file that size.
Thanks everyone.
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You have to de-interlace/re-interlace if you do a down conversion from interlaced HD to interlaced SD broadcast – regardless of the codec.
Spherico
https://www.spherico.com/filmtools
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