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Date: Sat, 21 Mar 2026 14:34:27 -0400
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Subject: Re: [ffmpeg hevc] Build require amd gpu
To: cygwin@cygwin.com
From: jeremie bergeron via Cygwin <cygwin@cygwin.com>
Reply-To: jeremie bergeron <jeremiebergeron1515@gmail.com>
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By curiosity, what is the patent issue?
The software decoder for hevc is LGPLv2.1, so why does it create an issue?

Note that this configure command will contain the software hevc decoder
(note that I haven't enabled gpl): ./configure --disable-programs
--disable-debug --disable-doc --disable-autodetect --enable-libdav1d
--disable-avdevice

Le sam. 21 mars 2026 à 06:20, Takashi Yano <takashi.yano@nifty.ne.jp> a
écrit :

> On Fri, 20 Mar 2026 23:23:33 -0400
> jeremie bergeron wrote:
> >* With ffmpeg 8.0.1-4, if I run the command: ffprobe hdr10tags-stream.mp4, I
> *>* get this error:
> *>* [AMF @ 0xa00056680] DLL amfrt64.dll failed to open
> *>* [hevc_amf @ 0xa00053800] Failed to create  hardware device context (AMF) :
> *>* Unknown error occurred
> *>* [mov,mp4,m4a,3gp,3g2,mj2 @ 0xa0004ca40] Failed to open codec in
> *>* avformat_find_stream_info
> *>* [AMF @ 0xa00056a40] DLL amfrt64.dll failed to open
> *>* [hevc_amf @ 0xa00053800] Failed to create  hardware device context (AMF) :
> *>* Unknown error occurred
> *> >* It is pretty normal that it fails since I don't have an amd gpu, so I
> *>* don't have the amfrt64 dll.
> *> >* Note that any hevc file will produce this error. hdr10tags-stream.mp4 is
> *>* available here:
> *>* https://storage.googleapis.com/ffms2tests/hdr10tags-stream.mp4 <https://storage.googleapis.com/ffms2tests/hdr10tags-stream.mp4>
> *> >* Would it be possible to disable this hardware decoder?
> *
> AFAIK, there is no options for ffprobe that disable hardware decoding.
> Usually, ffmpeg uses software decoder for hevc, however it is not
> included in cygwin ffmpeg package due to patent issue.
> So, ffmpeg attempts to use
> hevc_amf
> hevc_cuvid
> hevc_qsv
> If you have none of AMD/NVIDIA/INTEL GPU, you cannnot use HEVC codec
> at all unfortunately.
>
> In addition, when using NVIDIA GPU, but you do not specify "-c:v hevc_cuvid",
> ffmpeg attempts to use hevc_amf first, then after some errors, automatically
> uses hevc_cuvid as you observed.
>
> --
> Takashi Yano <takashi.yano@nifty.ne.jp>
>
>

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