On Mon, 21 Nov 2011 21:25:13 +0000
Ken Moffat <[email protected]> wrote:

> Hi Andy,
> 
>  I see you're intending to update ffmpeg, and I remember that in the
> past you've disagreed with the configure flags I added.  You seem to
> manage to keep up to date with so many projects that you probably
> know a lot more about this than I do, but nevertheless I'll offer my
> (edited) notes from when I upgraded to 0.8.4 -

Are you not tempted to update the page yourself? I don't mind, if you
want to do it, drive on. I only offered to do it 'cos the version in
the book is really old and I know a lot has changed with ffmpeg since
0.6.1. I see the latest version is 0.8.6. I've found that the new API
(the 0.8 releases) has broken a few things but they're mostly fixable
with seds.

> 
> 1. For uploading certain formats (.mov, .mp4) to youtube, I need to
> flatten them with  qt-faststart.  This was why I looked at newer
> versions, because this failed to build in the 0.6 versions on the
> system I was using (although it did build in older systems).
> 
>    make -C tools qt-faststart
>    install -m 0755 tools/qt-faststart /usr/bin

I think you should put that in the book :)

> 
> 2. A version of aac is included in ffmpeg (using it needs an
> override on the command line when ffmpeg is run using the aac
> acodec, [ -strict experimental ] (or, maybe only for encoding)
> so libfaac is not needed.

When I tried to encode an .m4a with ffmpeg it sounded terrible so I
always use faac to encode them. ffplay sounds great decoding an .m4a

> 
> 3. The internal ffacdec replaced libfaad during 0.7.
> 
> 4. --enable-version3 on top of --enable-gpl, to use gpl version 3 :
> I'm not sure if this changes what is built, or only its licence.
> 
> 5. --enable-pthreads to use threading.

andy@eccles:~$ '/home/andy/save/src/ffmpeg/configure' --help | grep
pthreads
  --disable-pthreads       disable pthreads [auto]

I think --enable-pthreads is the default.

> 
> 6. --enable-libvpx adds the libvpx decoder and encoder (there are
> other vp* decoders which might perhaps do this, unsure if that
> applies to encoders, I gave up noting the full list of them).

ffmpeg includes a libvpx decoder and the developers are quite pleased
with their decoder. --enable-libvpx adds an encoder to ffmpeg, but (my
attitude is) if you've installed libvpx, which includes vpxenc, why
would you need to use ffmpeg to encode a vpx video? I suppose it would
be used to allow ffmpeg to convert from one format to another without
piping from one application to another.

> 7. --enable-libvorbis adds the libvorbis encoder as well as the
> native vorbis encoder, there are claims that the libvorbis encoder
> is/was better (better-quality, ISTR).
> 
> 7. --enable-libtheora adds the libtheora encoder.
> 
> 8. --enable-libmp3lame adds the libmp3lame encoder.
> 
> 9. --enable-libx264 adds the libx264 encoder.
> 
> 10. --enable-libxvid adds the libxvid (xvidcore) encoder.
> 
> 11. I'm still using --enable-rtmp, but I have doubts if it is giving
> me anything extra.
> 
>  Hope this might be helpful, and not too out of date.

Thanks, it's interesting to think it through. I just use ffmpeg as a
dependency for other things (lots of things use it). For me, I just use
it for watching or listening to things encoded by other people but I
know from your emails to the lists that you use it to encode videos.
I build ffmpeg in a separate object directory and configure it:
  --enable-shared --disable-static --enable-postproc --enable-gpl
and that does everything I need. When I rip a cd I encode it to m4a
with faac and mp3 with lame. I think if I update the the ffmpeg page in
BLFS I will use the options that work for me but discuss the options
you've outlined above in the "Command Explanations" section; so I you
want all these encoder options to be the default in the book you should
update the page yourself. I think you should. I think you know more
about it than me. I can help fix the breakage that ffmpeg-0.8 will
introduce to other things.

Andy
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