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8-Channel H.264 Quicktime Files
To keep it short, I have a workflow that has been put together with one glaring issue that I haven’t been able to solve.
We have HD material with 8 channels of audio (5.1 mix + Stereo pair on Ch.7&8) that we record on to XDCam discs and pull MXF files off of with Vegas.
I’ve been asked to also create HD Quicktime files with H.264 codecs that RETAIN all eight channels of audio in their entirety. We’ve been using a Final Cut Studio station to handle the output of all things Quicktime, but when it comes to these, there seems to be issues.
Exporting the MXF files into Quicktime files with the Apple XDCAM codec is easy enough with “XDCam Transfer”, which we have. Exporting the Quicktime (XDCAM codec) files into Quicktime (H.264 codec) files also seems easy enough with Compressor, but for some reason the audio information always gets downmixed to channels 1 and 2.
I’ve tried using the Linear PCM setting with both the STMPE DTV configuration as well as all the 7.1 variations, as well as AAC audio with all its 8 channel configurations. It’s the same thing. (Although oddly the audio gets mixed down to channels 2 and 3).
Apparently letting the audio “pass-through” isn’t an option either since XDCam Transfer spits out the audio channels at 24-bit, but I’ve been asked specifically for 16-bit. Lousy restrictions.
Is there something I’m missing with Compressor? (Or possibly XDCAM Transfer?) I tried downloading a movie trailer from Apple’s website, which had AAC 5.1 audio and ran it through Compressor with the Linear PCM (STMPE DTV config) setting and there wasn’t a problem. It’s very strange.
Any insight would be appreciated.
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Dan Charrington
Supervisor, Non-Linear TechnologiesMIJO
635 Queen St E. Toronto, ON
416-964-7539MacPro 8-core Xeon 2.8GHz, 10gb Ram, AJA Kona 3 SD/HD
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10 Replies
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Make sure your audio output settings (in your sequence settings) are NOT set to stereo.
In Compressor…in the Inspector, click Audio/Settings, and select something other than stereo.
Does this work for you?
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Hi Dan,
I’ve never tried to do what you are trying, but I think QT Pro may be enough.
have a look to the “Add to movie” function.
If you have a QT movie to with 8 channels, you can “Extract” the audio channels (on Movie Properties) and add to any other QT movie. You can get the QT H264 done and just add the audio from the QT XDCAM files. basically is like Copy&Paste.
Probably there is some more elegant workflow, but I don’t know it.
rafael -
[Dan Charrington] “Exporting the Quicktime (XDCAM codec) files into Quicktime (H.264 codec) files also seems easy enough with Compressor, but for some reason the audio information always gets downmixed to channels 1 and 2. “
Is your export timeline setup as an 8 channel timeline or stereo?
From Compressor, you have to use the audio as pass through. If you need 16 bit audio, simply change the sequence setting before exporting.
Jeremy
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Thanks for the input guys.
Just to clarify, I’m actually not using Final Cut Pro at all in the encoding process. The Quicktime (XDCAM codec) files are going from XDCam Transfer right into Compressor.
I did some tests with exporting H.264 files out of Final Cut Pro, but I’m really not that impressed with how FCP handles interlaced content when encoding H.264. I like what Compressor does better.
The only reason I’ve been using FCP is to clearly check (with the waveforms turned on in the timeline) where the audio information ends up.
John, in the Inspector, I have indeed tried settings other then Stereo. I mentioned using the Linear PCM setting with both the STMPE DTV configuration as well as all the 7.1 variations, as well as AAC audio with all its 8 channel configurations. It’s the same thing. (Although oddly the audio gets mixed down to channels 2 and 3).
Rafael, your theory is one I also experimented with, and yes, that’s a viable option, but not within the time constraints and volume capacities I have to fire these out in. We get dozens of clips worth of material daily, and I can’t be anchored to the FCP station churning them out. Realistically, it’s Compressor (or some other form of set-it-and-forget-it batch exporting option, or bust.
For now, the “Pass-through” option seems to be making everyone happy, so I’m sticking with that. Jeremy, I will attempt your experiment down the line if I have time.
Thanks again.
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Dan Charrington
Supervisor, Non-Linear TechnologiesMIJO
635 Queen St E. Toronto, ON
416-964-7539MacPro 8-core Xeon 2.8GHz, 10gb Ram, AJA Kona 3 SD/HD
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[Dan Charrington] “Just to clarify, I’m actually not using Final Cut Pro at all in the encoding process. “
And you shouldn’t. In this case, I’d be using FCP to simply re-export the proper files as a reference movie and all audio channels were they need to be. This isn’t a transcode, it’s simply a wrapper/pointer to the original video media.
I don’t have an 8 channel XDcam MXF file here, but if you have a short one and don’t mind sending it, I can look at it.
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[Dan Charrington] “Rafael, your theory is one I also experimented with, and yes, that’s a viable option, but not within the time constraints and volume capacities I have to fire these out in. We get dozens of clips worth of material daily..”
Absolutely.
But, Dan, can you explain how they intend to use the H264 with 8 channels audio?
rafael -
No, Rafael. I really can’t. Mine is not to question why in this case. Mine is to give them what they want or they will cry.
I’m with you though. Of all things, why they want an H.264 is really beyond me when there are much better options.
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Dan Charrington
Supervisor, Non-Linear TechnologiesMIJO
635 Queen St E. Toronto, ON
416-964-7539MacPro 8-core Xeon 2.8GHz, 10gb Ram, AJA Kona 3 SD/HD
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It’s a moot point at this stage, since I’ve learned that is all a quick fix to a problem that apparently is going to get reworked by our engineers down the line, so I’m really not about to waste my (or your) time with it much further.
I was mostly just probing for answers out of curiosity. Thanks guys.
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Dan Charrington
Supervisor, Non-Linear TechnologiesMIJO
635 Queen St E. Toronto, ON
416-964-7539MacPro 8-core Xeon 2.8GHz, 10gb Ram, AJA Kona 3 SD/HD
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In the states, DG Fastchannel accepts 50 mb/sec h264 spots with surround + stereo (8 channels).
Maybe this is for a similar situation or a playback server of some sort. It’s not uncommon, Rafa.
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Thanks Jeremy.
With your info in mind, I would go to the “SONY XDCAM” or “Compression Techniques” Forum”, and ask directly Craig Seeman.
rafael
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