NAL_HRD relationship to VBV

Gregleto · 12th December 2013, 20:24

Hi all,

Our Telestream x264 GUI requires NAL_HRD to be enabled and set to VBR in order for us to set VBV. With NAL_HRD set to "Disabled", the option to set VBV numbers is disabled. Can anyone explain the relationship between VBV and NAL_HRD? More importantly, is there a dependency that requires NAL_HRD to be enabled in order to set VBV levels? It doesn't make sense to me so I feel I must be misunderstanding something.

Thanks,

Gregleto

Blue_MiSfit · 12th December 2013, 21:59

Well, I'm not the expert, but as far as I understand the HRD information is there to inform the decoder what vbv parameters were chosen by the encoder.

It's certainly possible to encode a stream using VBV without signaling NAL HRD or VCL HRD, but this may not work with all decoders. I think this is why Telestream inherently links the two options. I actually think this is a good idea, but again I'm not the expert.

12th December 2013, 20:24	#1 \| Link
Gregleto Registered User Join Date: Sep 2013 Posts: 38	NAL_HRD relationship to VBV Hi all, Our Telestream x264 GUI requires NAL_HRD to be enabled and set to VBR in order for us to set VBV. With NAL_HRD set to "Disabled", the option to set VBV numbers is disabled. Can anyone explain the relationship between VBV and NAL_HRD? More importantly, is there a dependency that requires NAL_HRD to be enabled in order to set VBV levels? It doesn't make sense to me so I feel I must be misunderstanding something. Thanks, Gregleto

12th December 2013, 21:59	#2 \| Link
Blue_MiSfit Derek Prestegard IRL Join Date: Nov 2003 Location: Los Angeles Posts: 5,989	Well, I'm not the expert, but as far as I understand the HRD information is there to inform the decoder what vbv parameters were chosen by the encoder. It's certainly possible to encode a stream using VBV without signaling NAL HRD or VCL HRD, but this may not work with all decoders. I think this is why Telestream inherently links the two options. I actually think this is a good idea, but again I'm not the expert. __________________ These are all my personal statements, not those of my employer :)

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