We should put a check into configure that disables FFmpeg if the available version is too new, or rather if it doesn't have the symbols we need available. Could be a bit of a pain to write and maintain however.

Fixes have recently been committed to support libav 0.8 to 0.10 and FFmpeg 1.2 to 2.2. There are still known issues, see Steps to Reproduce.

Created attachment 492 [details]
make log Ubuntu 13.10 with --disable-dynamic-loading

(In reply to comment #2)
@Benjamin, Audacity compiles for me at r13196 against self-compiled FFmpeg 2.2.2 on Ubuntu 14.04 with --disable-dynamic-loading. --disable-dynamic-loading still fails to compile on Ubuntu 13.10 against self-compiled FFmpeg 2.2.2 (even on fresh Audacity checkout). I attach the make log, but it shows similar "undefined reference to `av_codec_is_encoder'" errors as before.  

However there is a problem running my self-compiled FFmpeg standalone at the command-line on 13.10 (I can use FFmpeg in Audacity GUI if I perform default ./configure of Audacity). Running ffmpeg shows this terminal error:

relocation error: /usr/local/lib/libavfilter.so.4: symbol sws_isSupportedEndiannessConversion, version LIBSWSCALE_2 not defined in file libswcale.so.2 with link time preference.

Please advise if you think this error is causing Audacity not to compile with --disable-dynamic-loading.

(In reply to comment #3)
Gale wrote:
>  --disable-dynamic-loading still fails to compile on Ubuntu 13.10 against 
> self-compiled FFmpeg 2.2.2 (even on fresh Audacity checkout). 
That is, it fails with --disable-dynamic-loading the only argument, so using FFMPEG="system".   

Configuring with --disable-dynamic-loading and --with-lib-preference="local" (i.e. with "FFMPEG=local") does build, but the Libraries Preferences are not disabled.

The relevant part of the build log is:

audacity-FFmpeg.o: In function `import_ffmpeg_decode_frame(_streamContext*, bool)':
/home/gale/audacity/src/FFmpeg.cpp:364: undefined reference to `av_frame_alloc'
/home/gale/audacity/src/FFmpeg.cpp:414: undefined reference to `av_frame_free'
export/audacity-ExportFFmpeg.o: In function `encode_audio':
/home/gale/audacity/src/export/ExportFFmpeg.cpp:520: undefined reference to `av_frame_alloc'
/home/gale/audacity/src/export/ExportFFmpeg.cpp:592: undefined reference to `av_frame_free'
export/audacity-ExportFFmpegDialogs.o: In function `ExportFFmpegOptions::FetchCodecList()':
/home/gale/audacity/src/export/ExportFFmpegDialogs.cpp:1281: undefined reference to `av_codec_is_encoder'

I failed to reproduce the build failure. My guess is that the header files used mismatch with the avcodec library that should be linked against. What FFmpeg libraries do you have installed and where? Can you run these commands to shed some light on it?

find /usr/ -name avcodec.h
find /usr/ /lib -name 'libavcodec*.so*'
grep -H av_codec_is_encoder $(find /usr/ -name avcodec.h)

(In reply to comment #5)
> What FFmpeg libraries do you have installed and where? 
2.2.2 installed in /usr/local/lib.

> Can you run these commands to shed some light on it?
> find /usr/ -name avcodec.h

/usr/include/libavcodec/avcodec.h
/usr/local/include/libavfilter/avcodec.h
/usr/local/include/libavcodec/avcodec.h


> find /usr/ /lib -name 'libavcodec*.so*'

/usr/lib/vlc/plugins/codec/libavcodec_plugin.so
/usr/lib/i386-linux-gnu/libavcodec.so
/usr/lib/i386-linux-gnu/libavcodec.so.53
/usr/lib/i386-linux-gnu/libavcodec.so.53.35.0
/usr/lib/i386-linux-gnu/i686/cmov/libavcodec.so
/usr/lib/i386-linux-gnu/i686/cmov/libavcodec.so.53
/usr/lib/i386-linux-gnu/i686/cmov/libavcodec.so.53.35.0
/usr/local/lib/libavcodec.so
/usr/local/lib/libavcodec.so.55
/usr/local/lib/libavcodec.so.55.52.102

> grep -H av_codec_is_encoder $(find /usr/ -name avcodec.h)

/usr/local/include/libavcodec/avcodec.h:int av_codec_is_encoder(const AVCodec *codec);


Thanks!

Gale, do you still have an issue?

(In reply to Benjamin Drung from comment #7)
Don't know at the moment, Benjamin, I am on Ubuntu 14.04 now on the 32-bit machine, and I don't have a problem with compiling Audacity against self-built FFmpeg 2.2.2 installed into /usr/local and using dynamic loading (i.e. default Audacity ./configure).

It will be a while before I can test with dynamic loading disabled.

Steve wrote in email to me as we discussed this:

>It's been a long time since I attempted to build against the libav project, 
>but I've never managed to get this to work, even when carefully following 
>our documentation and using the versions stated.
>
>I have always disagreed with Gale's assertion that users should manually build
>and install an obsolete version of FFmpeg in order to use FFmpeg with Audacity.
>If Audacity is to remain a mainstream application on Linux, it must work 
>against system library versions that are commonly found in current versions of
>Linux. For common libraries, distribution maintainers will attempt to build 
>Audacity against system libraries. If Audacity does not work when built that 
>way, it will be dropped from their repository, and Audacity will no longer be 
>a mainstream application for Linux, and would essentially become 
>Windows / Mac only.
>
>Currently, Audacity builds against the system version of FFmpeg on Ubuntu 16.04.
>The last time I checked, it also worked with Ubuntu 18.04, so both of the 
>current "LTS" versions of Ubuntu appear to be covered for now.

I agree with Steve's assertion:  
>I have always disagreed with Gale's assertion that users should manually build
>and install an obsolete version of FFmpeg in order to use FFmpeg with Audacity.

Accordingly I shall close this as not a bug

Why do we keep FFmpeg in the lib-src build tree if this is not-a-bug?