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The world of Pro RES
Posted by Phil UK
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Re: The world of Pro RES November 12, 2008 12:17PM |
If you're working only in standard definition, then ProRes will be of marginal utility to you. Yes, it will get your data rates for SD material down to the 40-60 Mbps range, but it's been a long time since it was hard to handle multiple streams of uncompressed SD.
What ProRes is really for is to get the data rates for HD down to the 160-220 Mbps range, which is closer to what uncompressed SD requires. To accomplish this, ProRes compresses your footage quite a lot, really, but it does it in such a way that it's hard to see. This is especially true if your source material was compressed to begin with; HDV and XDCAM are the canonical examples of footage that is best worked with in ProRes format.
Until quite recently, taking delivery of ProRes material was difficult to do, since the ProRes software was only included with Final Cut Studio 2. But Apple has since released ProRes playback-only components for Mac and Windows, so anybody who could take a Quicktime before ? more or less ? should now be able to take a ProRes, or at least should now be able to get themselves ready to take a ProRes pretty easily. Of course, when it comes to delivery, you have to send what the client wants, so whether you can deliver as ProRes depends entirely on whether you client wants you to.
What ProRes is really for is to get the data rates for HD down to the 160-220 Mbps range, which is closer to what uncompressed SD requires. To accomplish this, ProRes compresses your footage quite a lot, really, but it does it in such a way that it's hard to see. This is especially true if your source material was compressed to begin with; HDV and XDCAM are the canonical examples of footage that is best worked with in ProRes format.
Until quite recently, taking delivery of ProRes material was difficult to do, since the ProRes software was only included with Final Cut Studio 2. But Apple has since released ProRes playback-only components for Mac and Windows, so anybody who could take a Quicktime before ? more or less ? should now be able to take a ProRes, or at least should now be able to get themselves ready to take a ProRes pretty easily. Of course, when it comes to delivery, you have to send what the client wants, so whether you can deliver as ProRes depends entirely on whether you client wants you to.
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Re: The world of Pro RES November 13, 2008 09:14AM |
>To accomplish this, ProRes compresses your footage quite a lot, really, but it does it in
>such a way that it's hard to see.
It's variable bit rate between 8-10 bits, quite likely DCT (it's kind of a secret, but we're guessing that it's DCT, since wavelets are very computationally intensive). And because it's variable bit rate, that's where you can grade in up to 10 bit quality, and it will drop off bits wherever it doesn't need it. It functions like the Avid equivalent of DNxHD- manageable file sizes at good quality. In fact, Steve Bayes was involved in the creation of both codecs.
You can use it either to transcode codecs that may cause you more problems in post (eg. AvcHD, HDV, XDCAM), or use it to save on storage (Uncompressed HD is a LOT of storage) and use that as a final master. It's made to hold up after multiple renders (you can probably go up to 10 generations without seeing much of a difference), making it more reliable for grading and round trip work than, say, HDV or XDCAM.
www.strypesinpost.com
>such a way that it's hard to see.
It's variable bit rate between 8-10 bits, quite likely DCT (it's kind of a secret, but we're guessing that it's DCT, since wavelets are very computationally intensive). And because it's variable bit rate, that's where you can grade in up to 10 bit quality, and it will drop off bits wherever it doesn't need it. It functions like the Avid equivalent of DNxHD- manageable file sizes at good quality. In fact, Steve Bayes was involved in the creation of both codecs.
You can use it either to transcode codecs that may cause you more problems in post (eg. AvcHD, HDV, XDCAM), or use it to save on storage (Uncompressed HD is a LOT of storage) and use that as a final master. It's made to hold up after multiple renders (you can probably go up to 10 generations without seeing much of a difference), making it more reliable for grading and round trip work than, say, HDV or XDCAM.
www.strypesinpost.com
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Re: The world of Pro RES November 13, 2008 10:32AM |
I love you, man, but that was actually pretty misleading. The bit rate of a format has nothing to do with the bit depth of the format.
ProRes 422 is a 10-bit codec with 4:2:2 chroma subsampling. If you use it to encode 10-bit footage, that footage will still have 10-bit precision. If you use it to encode 8-bit footage, that footage will be promoted to 10-bit, which doesn't actually buy you anything until you do something to that footage. If you put a vignette on it, for example, you'll be less likely to see banding with 10-bit precision.
The part where variable-bit-rate comes in is that ProRes doesn't allocate a specific number of bits to each frame, like DVCPRO does for instance. The actual data rate of your footage is impossible to predict, plus it changes from second to second, but for ProRes 422 HQ it will hover somewhere around 175 Mbps for 1080p24 and 220 Mbps for 1080i60.
ProRes is basically magic. I love it. I use it for everything.
ProRes 422 is a 10-bit codec with 4:2:2 chroma subsampling. If you use it to encode 10-bit footage, that footage will still have 10-bit precision. If you use it to encode 8-bit footage, that footage will be promoted to 10-bit, which doesn't actually buy you anything until you do something to that footage. If you put a vignette on it, for example, you'll be less likely to see banding with 10-bit precision.
The part where variable-bit-rate comes in is that ProRes doesn't allocate a specific number of bits to each frame, like DVCPRO does for instance. The actual data rate of your footage is impossible to predict, plus it changes from second to second, but for ProRes 422 HQ it will hover somewhere around 175 Mbps for 1080p24 and 220 Mbps for 1080i60.
ProRes is basically magic. I love it. I use it for everything.
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Re: The world of Pro RES November 13, 2008 10:49AM |
>I love you, man, but that was actually pretty misleading. The bit rate of a format has
>nothing to do with the bit depth of the format.
Yikes. I love you too man, but thanks for pointing that out. Bit rate is different from bit depth, and I do recall a variable 8 to 10 bit mention. Lemme just check that out. Okay, I must have mistaken that for something else.. It is 10 bit depth, but VBR. DNxHD has options to toggle between 10 and 8.
www.strypesinpost.com
>nothing to do with the bit depth of the format.
Yikes. I love you too man, but thanks for pointing that out. Bit rate is different from bit depth, and I do recall a variable 8 to 10 bit mention. Lemme just check that out. Okay, I must have mistaken that for something else.. It is 10 bit depth, but VBR. DNxHD has options to toggle between 10 and 8.
www.strypesinpost.com
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