[FFmpeg-user] Unable to initialize SDL, over X11 for only root

Wed Apr 4 01:31:01 EEST 2018

You guys were right! The magic cookie was not getting set, which was the root of the problem! All is working now. 

Thanks for the assist!

Jeff

> On Apr 2, 2018, at 18:44, Jeff <secjeff at gmail.com> wrote:
> 
> Return-Path: <secjeff at gmail.com>
> Received: from [192.168.1.2] (pool-100-15-204-239.washdc.fios.verizon.net.
> [100.15.204.239]) by smtp.gmail.com with ESMTPSA id
> a12sm1099978qtm.74.2018.04.02.15.44.58 for <ffmpeg-user at ffmpeg.org>
> (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 02 Apr
> 2018 15:44:58 -0700 (PDT)
> From: Jeff <secjeff at gmail.com>
> Content-Type: text/plain; charset=utf-8
> Content-Transfer-Encoding: quoted-printable
> Mime-Version: 1.0 (1.0)
> Date: Mon, 2 Apr 2018 18:44:58 -0400
> Subject: Re: [FFmpeg-user] Unable to initialize SDL, over X11 for only root
> Message-Id: <0A92FF2E-38E8-4CCF-8E3D-1CAB72D5304C at gmail.com>
> References: <20180402114631.GA16026 at sunshine.barsnick.net>
> In-Reply-To: <20180402114631.GA16026 at sunshine.barsnick.net>
> To: FFmpeg user questions <ffmpeg-user at ffmpeg.org>
> X-Mailer: iPhone Mail (15D100)
> 
> Moritz & Cley,
> 
> Thanks for the responses! I believe I checked most of these points, but I wi=
> ll do so more methodically to ensure I didn=E2=80=99t miss anything. =20
> 
> As far as why on the root user, I=E2=80=99m only speculating that=E2=80=99s h=
> ow this application is working. I know its daemon runs as root, so I=E2=80=99=
> m guessing that why it=E2=80=99s having issues calling ffplay. That said, a d=
> aemon calling it is different than me starting an interactive shell and call=
> ing it, so as you point out that may be where my issue is! I will dig into t=
> his more tomorrow and let you all know what I find.
> 
> Thanks again! I appreciate the great support you all provide.
> 
> Jeff
> 
>> On Apr 2, 2018, at 07:46, Moritz Barsnick <barsnick at gmx.net> wrote:
>> =20
>> Hi Jeff,
>> =20
>>> On Sun, Apr 01, 2018 at 16:28:28 -0400, Jeff wrote:
>>> However when running *ffplay* as the root user over X11 on the same files=
> ,
>>> I am getting met with the '*Unable to initialize SDL*' error.
>> =20
>> First of all: *WHY*?? There is usually no good reason to run anything
>> as root, if you are not administrating the system. If the user and
>> ffplay need access to some files or devices, grant the user access,
>> instead of using root.
>> =20
>>> I came across this (
>>> http://www.ffmpeg-archive.org/help-ffplay-Could-not-initialize-SDL-td4675=
> 063.html)
>>> thread/post form Moritz indicating there may be an issue using ffplay as
>>> root?
>> =20
>> The user never gave indication as to what he was doing, so we can't
>> know. My questions in the last e-mail are still valid.
>> =20
>>> In this particular case, there is a program daemon which is run as root
>>> that calls ffplay.  This is why the call is being made by the root user.
>> =20
>> A daemon that has access to a display? In that case, ffplay should be
>> called as something like "su <displayuser> -c 'ffplay'".
>> =20
>>> It seems something is different in the case of root over X11 vs. a direct=
> 
>>> terminal call from the root user's desktop, but I don't have the foggiest=
> 
>>> idea.
>> =20
>> I don't see a specific ffmpeg / ffplay issue. See Cley's answer: No X11
>> program may work at all. It has always been that way, at least for the
>> last 20 years or so. X11 uses "cookie authentication". To allow root to
>> use the user's cookies, you can either:
>> - open up access to the display using "xhost +local" (giving up all
>> security),
>> - migrate the auth cookie to the root process,
>> - use sudo from the user account to root (I think),
>> - log into root's account with "ssh -X" (which will automatically
>> migrate the cookie and give access via an SSH tunnel).
>> =20
>> The latter two require interactive use, I guess.
>> =20
>> Extra issue: If your display uses Xwayland, some of the above no longer
>> work. See also e.g. here:
>> https://bugzilla.redhat.com/show_bug.cgi?id=3D1266771#c4
>> =20
>> Cheers,
>> Moritz
>> _______________________________________________
>> ffmpeg-user mailing list
>> ffmpeg-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>> =20
>> To unsubscribe, visit link above, or email
>> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".
> Moritz & Cley,
> 
> Thanks for the responses! I believe I checked most of these points, but I wi=
> ll do so more methodically to ensure I didn=E2=80=99t miss anything. =20
> 
> As far as why on the root user, I=E2=80=99m only speculating that=E2=80=99s h=
> ow this application is working. I know its daemon runs as root, so I=E2=80=99=
> m guessing that why it=E2=80=99s having issues calling ffplay. That said, a d=
> aemon calling it is different than me starting an interactive shell and call=
> ing it, so as you point out that may be where my issue is! I will dig into t=
> his more tomorrow and let you all know what I find.
> 
> Thanks again! I appreciate the great support you all provide.
> 
> Jeff
> 
>> On Apr 2, 2018, at 07:46, Moritz Barsnick <barsnick at gmx.net> wrote:
>> =20
>> Hi Jeff,
>> =20
>>> On Sun, Apr 01, 2018 at 16:28:28 -0400, Jeff wrote:
>>> However when running *ffplay* as the root user over X11 on the same files=
> ,
>>> I am getting met with the '*Unable to initialize SDL*' error.
>> =20
>> First of all: *WHY*?? There is usually no good reason to run anything
>> as root, if you are not administrating the system. If the user and
>> ffplay need access to some files or devices, grant the user access,
>> instead of using root.
>> =20
>>> I came across this (
>>> http://www.ffmpeg-archive.org/help-ffplay-Could-not-initialize-SDL-td4675=
> 063.html)
>>> thread/post form Moritz indicating there may be an issue using ffplay as
>>> root?
>> =20
>> The user never gave indication as to what he was doing, so we can't
>> know. My questions in the last e-mail are still valid.
>> =20
>>> In this particular case, there is a program daemon which is run as root
>>> that calls ffplay.  This is why the call is being made by the root user.
>> =20
>> A daemon that has access to a display? In that case, ffplay should be
>> called as something like "su <displayuser> -c 'ffplay'".
>> =20
>>> It seems something is different in the case of root over X11 vs. a direct=
> 
>>> terminal call from the root user's desktop, but I don't have the foggiest=
> 
>>> idea.
>> =20
>> I don't see a specific ffmpeg / ffplay issue. See Cley's answer: No X11
>> program may work at all. It has always been that way, at least for the
>> last 20 years or so. X11 uses "cookie authentication". To allow root to
>> use the user's cookies, you can either:
>> - open up access to the display using "xhost +local" (giving up all
>> security),
>> - migrate the auth cookie to the root process,
>> - use sudo from the user account to root (I think),
>> - log into root's account with "ssh -X" (which will automatically
>> migrate the cookie and give access via an SSH tunnel).
>> =20
>> The latter two require interactive use, I guess.
>> =20
>> Extra issue: If your display uses Xwayland, some of the above no longer
>> work. See also e.g. here:
>> https://bugzilla.redhat.com/show_bug.cgi?id=3D1266771#c4
>> =20
>> Cheers,
>> Moritz
>> _______________________________________________
>> ffmpeg-user mailing list
>> ffmpeg-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>> =20
>> To unsubscribe, visit link above, or email
>> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".