On 12/10/2011 11:04 PM, Philipp Überbacher wrote: [..] > guess I'd need the whole track anyway before making > calculations.
Yes, but not all of it at the same time. You can calculate it sequentially. Have a look at https://www.ohloh.net/p/Samplecat it includes a ffmpeg audio decoder, max. gain calculation, Fons' ebur128 analysis and more.. Comment out the mime-type filter in main.c:788 to read the first audio track from a video file. >> https://github.com/avuserow/ffmpeg-replaygain seems to do what you want >> but requires ffmpeg av* libs <=0.5 and/or a bit of patching. > > My ffmpeg is rather recent (20111123) but the program doesn't build, so > I guess it needs patching. Seems like my ffmpeg is too new. The > implementation looks insanely complex to me. edit ffs.c replace "CODEC_TYPE_AUDIO" with "AVMEDIA_TYPE_AUDIO" and you are good to go with ffmpeg >0.5. For ffmpeg <0.5, replace the 'avcodec_decode_audio3() call with: int len = avcodec_decode_audio2(ffs->cc, (int16_t *) (buf + rdec), &size, tmppkt.data, tmppkt.size) [..] >> I don't know any command-line apps to modify meta-data on a per track >> basis in-place (maybe ffmpeg can do that?), but the new liav* meta-data >> API is pretty nifty. > > Do you refer to http://www.libav.org/ ? Sorry, a typo slipped in. Yes, libavformat, libavcodec, libavutil, etc.. I prefer libav* from ffmpeg.org not the branch libav.org. >>> Playback [..] >> A compressor plugin (for video-players that don't yet have one) would be >> much more useful in the real world because >> - purists won't care for neither replaygain nor compression > Agreed, if purists are people who only watch professionally produced > movies or similar. In such a case there'd be no need for it. > >> - consumers will complain that replay-gain is not sufficient for >> long[er] films and won't care about sound-degradation by compression > > Why would it not be sufficient for longer films? It can't do anything to > improve bad mixing, that's true, but there's not much one can do about > that anyway (except maybe apply some eq to make dialogs understandable). The single loud explosion (show down) or a slammed door will dwarf all the all whispered (sexy) dialog. I just ran `fbff` (ffmpeg replay gain) on a The Great Dictator (1940), Clockwork Orange (1971) and Avatar(2009). as well as http://www.youtube.com/watch?v=f2bcPIXl8kc They _all_ came out on zero (Max PCM value found: 1.000000, Title gain: 64.820000). Looks like they have been normalized already. (maybe youtube and DVD master[er]s do that?!) But the dynamics are completely different. For comparison, ebur128 reported: Loundness-range 19.1 LU; Peak 6.7 LU for the Chaplin movie. and Loundness-range 11.3 LU; Peak 15.3 LU for the youtube video, (Quite good actually, RHCP's 'Around the world' only features a Loundness-range 4.0 LU; Peak. 19.2.) [..] >> It's a great educational project with many problems that one will >> encounter in other /real-world/ projects. > > Thank you very much for that, I fear that it might be too hard. Most > students have very little coding experience. Most courses require little > coding and that is mostly done in java. > The course in question is a > beginner C/C++ course and for many students this was the first experience > with those languages. If you want to learn hands-on CS, don't study Informatics. Two years ago I taught the "advanced programming" class at the Kunst-universität Linz. 3rd semester *Art* school: > 1/3 of the students were fluent with openframeworks & openCV C++. The rest knew either JAVA/processing.org or Pure-data. I was pleasantly surprised. [..] >> Did you try http://www.akjmusic.com/software/jackctl20110317.py ??! > > I thought I knew them all... > Thanks, this is great and pretty close to what I/we imagined. I don't > fully understand the alsa midi mode, I think it doesn't use a pager for > many ports and I guess a way to connect a range of ports to another > would be useful as well, but it's really close to what I had in mind. > Julien will be happy to hear about this. > That pretty much takes care of this idea :) I think Aaron is on the LAD list. IIRC he announced it on LAU and LAA and may be willing to add a pager or other features. - just change the subject-line :) >>> More detailed ideas exist >>> thanks to Julien Claasen. >>> >>> - A simple but hopefully sane mplayer GUI >> >> RFTL. > > I sadly don't what that means :) AWW snap. ROFL. meaning: Mission impossible. "Die Idee ist gut, die Welt noch nicht bereit." (Tocotronic) >> http://www.mplayerosx.ch/ :( > > It looks reasonably nice, similar to smplayer, but the devil is in the > details. And this one seems to be for OSX only. That's why I'm sad. >>> - A new GUI for ecasound >>> >>> Another problem I might have is that most students in the course are >>> Windows users, not sure whether I can go solo. >> >> You can x-compile for windows and test with wine. ffmpeg is x-platform, >> as is mplayer and gstreamer. ..just be prepared to throw in a day or two >> to set up a x-platform build-environment. install mingw32 and wine. As long as a project uses autoconf: #export WINEBASEDIR=$HOME/.wine/drive_c/x-prefix #export PKG_CONFIG_PATH=$WINEBASEDIR/lib/pkgconfig/ #./configure --host=i586-mingw32msvc --build=i386-linux \ --prefix=$HOME/.wine/drive_c/x-prefix/ #make install Problem is: for ffmpeg you'll need a lot of time consuming dependencies. http://nsis.sf.net is the packager/installer tool of choice. but I'm getting more off-topic. > That's another possibility, thanks. > I guess I'll need to do something > like this no matter what the project will be. qemu or virtualbox? is nice for running or testing apps; but IMO developing in a VM - esp windows sucks much more than setting up a x-compile environment. > Thanks a lot Robin, > I'm pretty much back at square one now, but that's ok. Maybe I can > develop the ecasound GUI idea, maybe I should find a team first and try > to come up with an idea together with the others. I know that a /real wold use-case/ greatly excites students. Just you trade that for /real world experience/. The project is superb and IMHO not too complex: The /lazy/ student could just write a batch script: call `ffmpeg.exe` - parse output.., call `replaygain.exe` - parse output call `ffmpeg.exe -acodec copy -vcodec copy -metadata replaygain=X ..` and finish while you're still struggling with a gst-launch pipeline... Those students who are into C/C++ will at least manage to glue existing code and may learn about the basic mathematical complexities involved: bit-depth, logarithms.. The rich student will outsource it, and the creative student just delivers a remote-control for manual Volume control.. How many movies are you going to watch in your life vs. how long does it take to adjust the volume? robin _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
