[mythtv] Build system issues with FFmpeg 5.1

[Peter Bennett]

On 8/21/22 21:50, Scott Theisen wrote:
> On 8/21/22 21:43, Scott Theisen wrote:
>> Hello all,
>>
>> When I copy https://github.com/ulmus-scott/FFmpeg/tree/release5.1 
>> into MythTV and constify some pointers in libmyth/audio to satisfy 
>> -fpermissive, I get the following error:
>>
>> ```
>> make[2]: *** No rule to make target 
>> '../../external/FFmpeg/libswresample/libmythswresample.so.', needed 
>> by 'libmyth-33.so.33.0.0'.  Stop.
>> ```
>>
>> It should be `libmythswresample.so.4`.  In 
>> `mythtv/libs/libmyth/Makefile`, libmythavutil.so.57 has its version 
>> number, but libmythavcodec also is missing its version number.
>>
>> I suspect this is due to FFmpeg splitting their version macros across 
>> two files, version_major.h and version.h.  libavutil has an empty 
>> version_major.h, only using version.h.
>>
>> The problem appears to be in configure in get_version() on line 7749, 
>> but I have no idea how to fix it.  (Concatenating both files before 
>> processing with awk?)
>>
>> Any suggestions are greatly appreciated.
>>
>
> This appears to work, unless someone has a better suggestion:
>
> ```
> diff --git a/mythtv/configure b/mythtv/configure
> index 69c0a8f4c6..4fcc627a9a 100755
> --- a/mythtv/configure
> +++ b/mythtv/configure
> @@ -7750,7 +7750,8 @@ get_version(){
>      lcname=lib${1}
>      name=$(toupper $lcname)
>      file=$source_path/external/FFmpeg/$lcname/version.h
> -    eval $(awk "/#define ${name}_VERSION_M/ { print \$2 \"=\" \$3 }" 
> "$file")
> + file_major=$source_path/external/FFmpeg/$lcname/version_major.h
> +    eval $(awk "/#define ${name}_VERSION_M/ { print \$2 \"=\" \$3 }" 
> "$file_major" "$file")
>      enabled raise_major && eval 
> ${name}_VERSION_MAJOR=$((${name}_VERSION_MAJOR+100))
>      eval 
> ${name}_VERSION=\$${name}_VERSION_MAJOR.\$${name}_VERSION_MINOR.\$${name}_VERSION_MICRO
>      eval echo "${lcname}_VERSION=\$${name}_VERSION" >> $TMPMAK
> ```
>
>
I suggest add comments above the awk stuff, explaining what the purpose 
is, as you did above, that is is needed because of the two version 
header files.

Peter