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FCP gamma shift on export, final QT file codecs & print to tape problems
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FYI: here’s some info I found on M-JPEG vs P-JPEG. I’m new to using either as a final QT codec, so I’m learning! 🙂
“Both the M-JPEG codecs (A&B) allow fields and a field order to be specified, and if used the fields are compressed separately and then combined. This prevents artifacts from mushing fields together, and at lower quality settings this can make a significant difference. For this reason alone, anyone working with interlaced video should use the MJPEG codecs and not the Photo JPEG codec.
At quality levels below 100%, chroma is downsampled respective to the
quality level selected, but Photo JPEG samples at 4:2:0 (ie. vertical
samples) while the MJPEG codecs sample at 4:2:2 (ie. horizontal
samples). In terms of video footage, this relates to a fields issue and is another reason why you should use MJPEG codecs for interlaced footage instead of Photo JPEG.”I hope the info helps other users…
Timothy Gassen
Director/Producer -
[Timothy Gassen] “I haven’t found any resources that confirm P-JPEG is for interlaced SD footage.”
Have you find any that says is only for progressive?
To make a codec progressive-only makes no sense. That means that you couldn’t use it for HD.
M-JPEG was only for interlaced because at that time all video was interlaced.
As long as I know every (modern) codec is field-order agnostic. it has to be able to work as Upper/lower and Progressive.[Timothy Gassen] “M-JPEG, I’m told, can be re-inserted in FCP as a legacy export option, and I’ve read it’s an option many FCP users wish had never been deleted.”
A couple of versions back of QT.7 you still had the option (QT Preferences) of “Show Legacy codecs”. In the last QT.7 version, the options don’t exist anymore.[Timothy Gassen] “DV has been a great acquisition format, but degrades greatly as an edit format. Working natively in DV is not the best quality solution, at least in FCP. “
Right, but you capture and edit DV and change your sequence codec (Uncompressed or prores) to avoid further DV recompression. You don’t render again in DV.[Timothy Gassen] “Regardless, it seems I’ve been unable to get the firewire on the FCP machine at the facility I’m working at to give the actual rendered file out to tape. It could be the “print-to-tape” function is not working correctly in this install — but it appears to be sending draft quality out, not the rendered sequence. I’m thinking I’ll have to bring final QTs back into a Media 100 if I want a quality firewire out to DVcam…”
Most of us we have been working for years with DV and printing back to tape without problems.
Do you have FC set to full quality playback?[Timothy Gassen] “”Both the M-JPEG codecs (A&B) allow fields and a field order to be specified, and if used the fields are compressed separately and then combined. This prevents artifacts from mushing fields together, and at lower quality settings this can make a significant difference. For this reason alone, anyone working with interlaced video should use the MJPEG codecs and not the Photo JPEG codec.”
The guy who wrote that has certain idea but he didn’t understood it.
M-JPEG is a codec from before the NLEs and needs a way to specify Upper or lower first encoding. However this won’t makes any sense in QT because QT do not manage field order. QT only needs to know if the stuff is interlaced or progressive, because on both cases CHROMA is compressed in different ways.
Photo-JPEG is a codec developed for NLEs. Is your NLE who will set the field order of the compressor.
Have a look to the date of that document.[Timothy Gassen] “At quality levels below 100%, chroma is downsampled respective to the
quality level selected, but Photo JPEG samples at 4:2:0 (ie. vertical
samples) while the MJPEG codecs sample at 4:2:2 (ie. horizontal
samples). In terms of video footage, this relates to a fields issue and is another reason why you should use MJPEG codecs for interlaced footage instead of Photo JPEG.””
That’s absolutely wrong. the class of information that should be trashed from internet.
This link contains the best info on QT codec that have been done so far:https://onerivermedia.com/codecs/
Click on the “422C” tab.
rafael -
Rafael (and all),
Thanks again for your responses and patience as I try to learn & figure this out!
As for P-JPEG vs M-JPEG, I found this, credited to “Sam Bushell,
QuickTime Engineering” – “If you’re compressing non-interlaced content, use Photo JPEG. If you’re compressing interlaced content in software in the abscence of any hardware or expected hardware, you should choose Motion JPEG A.”Again, I am not an expert and I dont’ know which codec is appropriate, so I’ll try more P-JPEG tests along with M-JPEG…
BTW, we were able to (after much hoop-jumping) re-insert the M-JPEG codec back into Compressor. We must not be running the newset version of QT, where that option isn’t allowed…
As for our DV out problem: Yes, we changed our sequence to a better codec for the edit, but I thought it needed to be copied back to another sequence and re-rendered as DV before it could be sent back through firewire to a DV/DVcam deck? We did try sending to firewire from our uncompressed-codec sequence and it DID go to firewire, but again in what appears to be the “draft quality” that we got from our DV sequence. Again, the video played from our timeline looks OK — the video sent through the firewire has additonal “mosquito-noise” artifacts. All our settings are set to Full/Best…
Thank you all again for your thoughts and suggestions!
Timothy Gassen
Director/Producer -
FYI: To turn on Quicktime legacy codecs in Snow Leopard: open Terminal then “Shift + Command(⌘) + N” and enter the following code:
qtdefaults write LegacyCodecsEnabled yesAfter more test encodes, P-JPEG is not working for our SD footage. There is no control for field dominance in the export to P-Jpeg, and it appears to be upper-dominant, causing obviuous confilict with our lower-dominant SD footage.
M-JPEG quality is good, but a shame that in order to use the gamma correction on export that we have to go through Compressor, and can’t do a straight QT Export or use Conversion…
FYI: After tests, a gamma correction of 1.3 in Compressor appears to make our final QT files have the same gamma as the original master footage…
Timothy Gassen
Director/Producer
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