Re: FFmpeg-8.0 Warning

On 9/24/25 6:06 PM, Joe Locash ([email protected] via blfs-dev Mailing List) wrote:
> On 9/24/25 6:45 PM, Bruce Dubbs ([email protected] via blfs-dev Mailing List) wrote:
>> On 9/24/25 3:46 PM, Joe Locash ([email protected] via blfs-dev Mailing List) wrote:
>>> On 9/23/25 7:31 PM, Bruce Dubbs ([email protected] via blfs-dev Mailing List) 
>>> wrote:
>>>> On 9/23/25 6:22 PM, "Douglas R. Reno" ([email protected] via blfs-dev 
>>>> Mailing List) wrote:
>>
>> [snip]
>>
>>>>>>>> Then I created a script:
>>>>>>>>
>>>>>>>> $ cat firefox-ffmpeg8
>>>>>>>> #! /usr/bin/bash
>>>>>>>>
>>>>>>>> export LD_LIBRARY_PATH=/opt/ffmpeg8/usr/lib/
>>>>>>>> firefox
>>>>>>>>
>>>>>>>>
>>>>>>>> And ran a random youtube video.  It seemed to play fine, but I'm not sure if 
>>>>>>>> it picked up the right libraries.
>>>>>>>>
>>
>> [snip]
>>
>>>>>> In the case of firefox, I can't tell for sure which version of, say, 
>>>>>> libavcodec.so it is using.  I have two:
>>>>>>
>>>>>> $ ll /usr/lib/libavcodec.so
>>>>>> lrwxrwxrwx 1 root root 23 Aug 21 18:02 /usr/lib/libavcodec.so -> 
>>>>>> libavcodec.so.61.19.101
>>>>>>
>>>>>> $ ll /opt/ffmpeg8/usr/lib/libavcodec.so
>>>>>> lrwxrwxrwx 1 root root 23 Sep 23 13:36 /opt/ffmpeg8/usr/lib/libavcodec.so -> 
>>>>>> libavcodec.so.62.11.100
>>
>> [snip]
>>
>>>> So it is loading ffmpeg7.  Upon reconsideration, a library libxxx.so is normally 
>>>> only used at link time.  Trying to use LD_LIBRARY_PATH won't work in this 
>>>> circumstance will not work. 
>>>
>>> LD_LIBRARY_PATH will work. Firefox doesn't directly link against a specific 
>>> version of the ffmpeg libraries. It's internal code accounts for various versions 
>>> of ffmpeg and then checks for the version of the ffmpeg libraries that might be 
>>> installed. See dom/media/platforms/ffmpeg/FFmpegRuntimeLinker.cpp in the FF source 
>>> for more info on the versions checked for. It will find the ffmpeg-7 libs just 
>>> fine using LD_LIBRARY_PATH.
>>
>> Joe,  In my test it didn't work.  In my test script above I tried to redirect the 
>> location to the ffmpeg8 libraries with LD_LIBRARY_PATH, but it still picked up the 
>> ffmpeg7 libraries. 
> 
> I don't think you completely understand the issue.  The problem is that firefox will 
> not even attempt to open the ffmpeg-8 libraries (mainly libavcodec.so.62) because 
> it's internal ffmpeg code doesn't look for that library so changing LD_LIBRARY_PATH 
> will have no effect. On a system with ffmpeg-8 only installed parts of firefox are 
> broken (mainly streaming). Installing the ffmpeg-7 libs or changing LD_LIBRARY_PATH 
> to include the location of those libs will fix the issue.

I was pretty much aware of that after testing, but thanks for confirming.  What I 
wanted to do was to run alternate instances of FF with different ffmpeg libraries 
just for testing before updating BLFS.  As of right now it doesn't seem doable.

   -- Bruce

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