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Author Topic: Alpha channel in videos  (Read 4834 times)

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« on: July 26, 2008, 03:07 »
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Hi list,

IS has some videos where the description says an alpha channel is included. I am preparing some rendered animations, using png with transparency as output. How can I produce a video which includes the alpha channel? One of those videos on IS uses the Motion JPEG A codec, but it was my understanding that this doesn't support alpha, so I am a bit confused. How is this done?


« Reply #1 on: July 26, 2008, 06:22 »
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The few ones I've seen on IS include the plain footage followed by the alpha channel. So the video file is twice longer than the footage time.
The buyer then "selects" the second half of the footage and uses it as an alpha channel in video editing software.

« Reply #2 on: July 26, 2008, 06:48 »
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The few ones I've seen on IS include the plain footage followed by the alpha channel. So the video file is twice longer than the footage time.
The buyer then "selects" the second half of the footage and uses it as an alpha channel in video editing software.

Right. It's not technically an alpha channel. Rather a luma keyable version added to the end of the clip. A true alpha channel can be created by the buyer using this, or they may just use the luma key to composite the clip.

« Reply #3 on: July 26, 2008, 06:50 »
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Ah, I understand. That is easy to do. Thanks for your help, both of you!

« Reply #4 on: July 26, 2008, 06:52 »
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« Reply #5 on: July 26, 2008, 07:59 »
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Thanks! I had searched their forums but did not come across this article. It is very helpful.

« Reply #6 on: August 03, 2008, 22:28 »
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Pond5 accepts files encoded using the ANIMATION codec which supports a true alpha channel.  Less work. :)


 

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