Playing a 23.976fps image sequence W/audio in Pandora

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Playing a 23.976fps image sequence W/audio in Pandora

Postby rjsheppard23 » Fri May 01, 2015 4:24 am

Hi, I am attempting to play a 23.976fps PNG image sequence on a Pandoras Box EDU dongle, However i am noticing that pandoras box only supports whole frame sequence frame rates, i.e 24fps not 23.976 or 23.98.

Because i am playing the png sequence on a 24fps timeline it looses sync with the audio as the image sequence is playing faster than intended.

I am basically just looking for a way to play back a image sequence at a true 23.976 or 23.98 frame rate.

Any help is greatly appreciated!!

Thanks, Ryan
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Re: Playing a 23.976fps image sequence W/audio in Pandora

Postby Daniel Kaminski » Fri May 01, 2015 7:56 am

Hi,

please try rendering it into a MOV Container using the Coolux Codec.
What kind of Projekt is this for. Just want to understand why you use 23.976?

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Re: Playing a 23.976fps image sequence W/audio in Pandora

Postby malkuth23 » Fri May 01, 2015 8:04 pm

Usually as operators we have little control of how the content comes in.
23.97 is a common enough frame rate. Especially coming from the "film" world.
We can request a whole number, but content creators go off on their own all the time.
Often the content is created long before the media server related project ever existed and changing the frame rate of an existing piece of content is a lengthy process.

Importing an image at non-whole-number rates would be useful.
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Re: Playing a 23.976fps image sequence W/audio in Pandora

Postby Daniel Kaminski » Fri May 01, 2015 9:17 pm

I Agree, it probably would be, especially since we are not gonna change this DropFrame craziness.
But right now this might be an solution you can try. Hopefully it works and your Production can happen and your Audio will stay in sync.
I will also put this in as a Feature Request.

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Re: Playing a 23.976fps image sequence W/audio in Pandora

Postby florian » Mon May 04, 2015 4:47 pm

Vaguely related:

I would try to steer away from playing back PNG sequences in a production environment. The PNG encoding is lovely as far as image quality goes (QT PNG's gamma issues notwithstanding), but the quality/performance ratio of PNG sequences is not very good since decoding a PNG has a variable but reliably high performance penalty.
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Re: Playing a 23.976fps image sequence W/audio in Pandora

Postby rjsheppard23 » Thu May 21, 2015 7:54 pm

Sorry for the late reply! unfortunately re-rendering all of the content was not an option as we had over 1tb of image sequences to play back. We had chosen the PNG image sequences solely for quality purposes as we were playing back short films.

However, We did find a workaround! we were able to playback the 23.976fps sequences at 24fps and stretch the audio by 0.1%. We used this as a rule of thumb for each film and the audio stayed synced for every film after that.

In terms of performance we had 0 issues, as we were only playing back one sequence on one layer at a time off an SSD. However yes i am aware to avoid using them in a normal show situation.

I wish i could say theres no need for 23.976 frame rate timelines but it is still an extremely common frame rate in film and its pretty disappointing that PB cant play them back properly.
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Re: Playing a 23.976fps image sequence W/audio in Pandora

Postby aquapixs » Sat May 23, 2015 10:14 pm

Hey Flo,

what would be your recommended file type to playback? I love image sequences but as you said png is quite bad in terms of performance. The other oprtion would be DDS which offers good performance but bad image quality. So what are you going for right now?

Cheers

Patrick
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Re: Playing a 23.976fps image sequence W/audio in Pandora

Postby florian » Sat May 23, 2015 11:16 pm

Hi Patrick,

Daniel did a great roundup of supported codecs here:
viewtopic.php?f=2&t=3730

PNG is lovely because the image compression is lossless 8-bit per channel, but the performance penalty makes it an unwieldy beast. Especially since it is effectively a VBR encode for your videos.

the coolux QT plugin recently added YCoCg. This combined with the Google Snappy compression is basically exactly what HapQ is, but I am given to understand that the container is formatted in a way that makes it play nicer with Pandora's Decoder stack.

I have done some tests with HapQ and found it works really well for camera footage. Others have reported issues with gradients in CG content, though I think this is actually a problem with the colorspaces that most content producers work in these days (in other words: if you produce digital media in a floating point color space, you NEED TO ADD NOISE/DITHERING or your gradients will get rounded to the nearest neighbor, which results in banding).

I think coolux DDS is actually pretty good, but it lacks the extra Luma data that you can pack into YCoCg, so it would probably show more banding in gradients from darker to lighter colors.

The biggest issue I have with the coolux DDS/YCoCg codecs at this point is that the compression is slooooow. I'm in a theater as I am writing this, and we actually just do draft renders for testing content in Pandora using M2V CBR because it takes about 1/4th the time. For all the high fidelity of our color/image encoding, MPEG-2 still manages to fit a workflow performance sweet spot sometimes.
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Re: Playing a 23.976fps image sequence W/audio in Pandora

Postby aquapixs » Sat May 23, 2015 11:51 pm

Hi Flo,

thanks for your opinion. I know Daniels post since it had been inspired by a long discussion I had with him regarding this topic.
I was courious about your opinion :-)

Thanks

Patrick
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