[FFmpeg-devel] sizeof(HEVCVPS)

[FFmpeg-devel] sizeof(HEVCVPS)

[Michael Niedermayer]

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Hi

why is sizeof(HEVCVPS) is 7463476 ?

If you think about this for a moment, a VPS in the bit stream is what, 5 bytes ?

Now iam not even talking about someone proving you a 10mb file with a million VPSs
7TB allocation, memsets memcpies, ...

But even with a totally normal file 7mb is easily bigger than the frame buffer
that wastes memory, it wastes cpu time, it wastes data cache

thx

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Frequently ignored answer#1 FFmpeg bugs should be sent to our bugtracker. User
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Re: [FFmpeg-devel] sizeof(HEVCVPS)

[Lynne]

Mar 20, 2024, 23:24 by michael@niedermayer.cc:

> Hi
>
> why is sizeof(HEVCVPS) is 7463476 ?
>
> If you think about this for a moment, a VPS in the bit stream is what, 5 bytes ?
>
> Now iam not even talking about someone proving you a 10mb file with a million VPSs
> 7TB allocation, memsets memcpies, ...
>
> But even with a totally normal file 7mb is easily bigger than the frame buffer
> that wastes memory, it wastes cpu time, it wastes data cache
>

As discussed on IRC, Vulkan ran into this.
The size of all HEVC structs (SPS, VPS, PPS) at their maximum array sizes is ~120 Mb.
That's why there's a function in Vulkan to allocate them on demand.
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Re: [FFmpeg-devel] sizeof(HEVCVPS)

[James Almer]

On 3/20/2024 7:23 PM, Michael Niedermayer wrote:
> Hi
> 
> why is sizeof(HEVCVPS) is 7463476 ?
> 
> If you think about this for a moment, a VPS in the bit stream is what, 5 bytes ?
> 
> Now iam not even talking about someone proving you a 10mb file with a million VPSs
> 7TB allocation, memsets memcpies, ...
> 
> But even with a totally normal file 7mb is easily bigger than the frame buffer
> that wastes memory, it wastes cpu time, it wastes data cache
> 
> thx

Posted a patch for this.
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