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Hi.

I have problems with the chapter timecodes in 23.976 fps:

Please try this:

Create a simple project with one segment (23.976 fps) and one playlist containing this segment. Add six chapters to it at:

00:10:00:00

00:20:00:00

...

01:00:00:00

Then build it and play it. If you've used a proper video asset you'll notice, that the chapters are off on playback. Now open the "compile.doCs" file that was created during the build. You will find the following lines in it:

<BDPlayListMark MarkFrameIndex="14385" marktype="chapter" />
<BDPlayListMark MarkFrameIndex="28771" marktype="chapter" />
<BDPlayListMark MarkFrameIndex="43156" marktype="chapter" />
<BDPlayListMark MarkFrameIndex="57542" marktype="chapter" />
<BDPlayListMark MarkFrameIndex="71927" marktype="chapter" />
<BDPlayListMark MarkFrameIndex="86313" marktype="chapter" />

So the timecodes are converted to frames for the Corel PUREHD multiplexer BUT

00:10:00:00 is 14386 frames (1 frame off)

00:20:00:00 is 28772 frames (1 frame off)

00:30:00:00 is 43156 frames (0 frames off)

00:40:00:00 is 57542 frames (0 frames off)

00:50:00:00 is 71928 frames (1 frames off)

01:00:00:00 is 86314 frames (1 frames off)

If you don't use so "even" timecodes the calculation can be +-3 frames off (the maximum I've found so far). The main problem is, that your carefully aligned IDR-Frames don't match the chapter times now. This can lead to unpredictable results.

The versions 2.6 and 3.0 have this problem. I didn't check other versions. 24 and 25 fps don't have this error.

CU

Kai

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Hello Kai, What version exactly of DoStudio 3.0 are you using? Do you have the latest DSA 3.0 build 71 installed?

Thanks, Rob

Hello Kai, It is our recommendation that you base your chapter points TC mark on 23.98 not 23.976. As you know DoStudio and the Multiplexer recognize only 23.98 not 23.976. It is this variance that is drifting the chapter TC frames that are calculated.

Unfortunately, there are encoders and other tools that only use 23.98 fps. DoStudio long ago settled on this frame rate use as well.

Thank you, Rob

Hi.

Rob Aubey said:

Hello Kai, It is our recommendation that you base your chapter points TC mark on 23.98 not 23.976. As you know DoStudio and the Multiplexer recognize only 23.98 not 23.976. It is this variance that is drifting the chapter TC frames that are calculated.

In fact there is no drift. The error isn't increasing over time. As you can see in the above example it is jumping around.

Unfortunately, there are encoders and other tools that only use 23.98 fps. DoStudio long ago settled on this frame rate use as well.

According the DoStudio manual (http://dspcdn.sonycreativesoftware.com/dostudio/manuals/DSA30.0.71_... page 173) this is not true. In fact I don't know any encoder that encodes at 23.98 fps. Some use the number as an abbreviation for 23.976 but actually encode at 23.976.

A little side note: If you create (a not Blu-ray conform) 23.98 fps file the 00:10:00:00 TC must be at frame 14388. The Sony guys have to double check this code, I think...

Thank you, Rob

Thank you, but I think this is work for the code gurus

Kai

Kai,

Correct - "drift" was not the correct word to use. My mistake.

The chart you point to in the manual is taken from the BDA Blu-ray specs. It is only a definition of compliance of streams.

I will look into this further.

Rob

Hi Rob

On this brief topic of Encoders using 23.98. I'm assuming Blu-code uses 23.976....correct? If so, this would explain sync issues with Subtitles when we apply the Multiplexer in DSA (vs2.6) at 23.98. Our current solution is setting the Multiplexer as true 24. This sets resolves our sync issues with subtitles.

Marcus


Rob Aubey said:

Hello Kai, It is our recommendation that you base your chapter points TC mark on 23.98 not 23.976. As you know DoStudio and the Multiplexer recognize only 23.98 not 23.976. It is this variance that is drifting the chapter TC frames that are calculated.

Unfortunately, there are encoders and other tools that only use 23.98 fps. DoStudio long ago settled on this frame rate use as well.

Thank you, Rob

That is correct Marcus. I understand that others do the same with the settings in DSA to get accurate chapter placement results.

 

We are continuing to look into this issue overall as well.

 

Blu-ray 2D encoders will do 23.976 encodes for primary streams as required by BD spec. It is some encoders that list it as 23.98.

 

--Rob

We also export 24fps chapter tcs to get around the drifting chapters with 23.976...

I get also wrong calculated chapters inside of a multi segment playlist in a 24p projects.
Any stupid offset will be applied to my chapter points in background.
The chapter marker does not match any of the choosen TC positions.

Strange!

Andreas

I have an issue related to this, but probably not exactly the same.

A 13 minute 23.98 quicktime exported from Final Cut Pro 7 needs chapters at 4:17:11 and 6:01:18

But to get these chapters to be in the right place after compliling I have to set them in dostudio at 3:26:00 and 4:50:00

this is not the first time my chapters required manual adjusting which makes it a bit of a challenge since they cannot be set visually.

any hints or ideas?  I have tried re-exporting the clip "recompress all frames" but it did not make any difference.

-cris

Hi Chris

What is your Multiplexer set up in your DSA project? This should be setup as 23.98 or 24. Also, what are using as an encoder?

Hi Chris,  a couple of items to check.

Does your TC text file have a chapter #1 at 00:00:00:00. Or are you entering them in manually? DSA requires the first chapter be 00:00:00:00 in either case.

Make sure the video segment has the FPS set to the video FPS. 23.98 I assume?

Thanks, Rob

Hi Rob,

Thanks much for the hint!  I found that drop down and it was set to 29.97.

Nice to hear from you.

Chapters are working as intended now :)

-cris

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