Does Handbrake eliminate filler Bytes (NALUs)?

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Filmriss
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Does Handbrake eliminate filler Bytes (NALUs)?

Post by Filmriss » Sat Aug 12, 2017 9:12 pm

Does it?

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Rodeo
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Re: Does Handbrake eliminate filler Bytes (NALUs)?

Post by Rodeo » Sat Aug 12, 2017 9:39 pm

You'll have to be more specific about what you mean by "filler bytes", that can mean several things. Also a context about why you care/need to know would help :)

Filmriss
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Re: Does Handbrake eliminate filler Bytes (NALUs)?

Post by Filmriss » Sat Aug 12, 2017 9:50 pm

OK :)

In Germany the public TV broadcasters send VBR streams in a CBR set, so they need to fill it with filler bytes. My PVR can record them. I would like to save them to my PC (e.g. for educational purpose) and I wondered, if I should eliminate the filler bytes beforehand in a remux tool or if Handbrake does this anyway.

Woodstock
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Re: Does Handbrake eliminate filler Bytes (NALUs)?

Post by Woodstock » Sat Aug 12, 2017 10:57 pm

If what you're referring to is the redundant, out-of-sequence frames that are sent as part of an over-the-air broadcast, those can be problematic, and you may need to repair the data stream before it gets to handbrake.

But running a test encode, and providing the logs generated, would help with this currently-theoretical discussion.

WhatZit
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Re: Does Handbrake eliminate filler Bytes (NALUs)?

Post by WhatZit » Sun Aug 13, 2017 6:14 am

Woodstock wrote:
Sat Aug 12, 2017 10:57 pm
If what you're referring to is the redundant, out-of-sequence frames that are sent as part of an over-the-air broadcast, those can be problematic, and you may need to repair the data stream before it gets to handbrake.
No, he's referring to the all-too-common NAL Unit Type 12/0x0C (Filler Data, Non-VCL), defined by the header byte immediately following the Start Code.

Therefore, I believe what he was actually asking about was whether type 12 payload data in the source is discarded by HandBrake.

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Rodeo
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Re: Does Handbrake eliminate filler Bytes (NALUs)?

Post by Rodeo » Sun Aug 13, 2017 11:37 am

Yes, HandBrake decodes the bitstream to uncompressed video in RAM, at which point the input bitstream characteristics are no longer applicable. The video decoder is capable of discarding these NAL units just fine. And our video encoders don't insert such units in the output bitstream unless specifically requested.

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