For those who are interested in raop2 experiments, As Matthias pointed out [1], current volume calculation is incorrect. https://bugs.freedesktop.org/show_bug.cgi?id=42804#c43 I have uploaded a patch which calculates volume in more reasonable way. https://github.com/hfujita/pulseaudio-raop2/commit/69f3ce883dfb93eb7b24f98b9664e14071672475 First I have to confess that this is the first time for me to deal with the unit 'dB', so maybe I'm doing totally stupid. I'd be very happy if I could have any suggestions from who is more experienced in this field. I started looking at pa_raop_client_set_volume() in src/modules/raop/raop_client.c. It was using pa_sw_volume_to_dB to calculate dB from a linear scale. Then I learned from code reading that pa_sw_volume_to_dB essentially calculates the following: 20 * log10((v/MAXVOLUME)^3) = 60 * log10(v/MAXVOLUME) This does not fit into the volume scale which RAOP is expecting, where -30.0 db is a kind of minimum [2]. [2]: http://git.zx2c4.com/Airtunes2/about/#id29 Also I looked at packet dumps from iPad and guessed how it calculated dB from a linear scale. It looked like iPad was using the following formula. db = 10 * log10(volume/MAXVOLUME/30) So for the time being I decided to follow this way. In my environment (Pioneer VSX-43), volume 10%-15% (about -25db~-23db) is the most comfortable setting. Bigger than that is too loud and my neighbors will get upset :( Please try the latest patch and let me know what volume is the best for you. I strongly recommend your to start from quite low volume (5%), and slightly change the volume. Thanks, Hajime Hajime Fujita wrote: > Hello, > > Recently I found that the current PulseAudio did not support the latest > AirPlay audio streaming, so I started to brush up the raop2 > implementation based on Christophe Fergeau and Martin Blanchard's > implementation. > > Here is my ongoing work. > https://github.com/hfujita/pulseaudio-raop2 (repo) > http://hfujita.github.io/pulseaudio-raop2/ (brief document) > > My primary goal is to enjoy musics in my AV receiver from Linux, but a > vague ambitious is to get the code merged into upstream so that anyone > can use the feature by just using distro packages. > > Current status: > * Plays music with Pioneer VSX-43. > * Sound test (launched from the GNOME sound setting dialog) does not > work (no sound heard). > * When stop playing music and then start again, PulseAudio may go into > an abnormal state (no sound/hang up/crash). > * Works reasonably fine with VLC/totem but when playing music from > Rhythmbox, quite rough sound is heard. > * Packet retransmission is not supported yet. > > I'm very happy to hear any sort of suggestions. > In the near future I may ask several technical questions about > PulseAudio internals. > > > Thanks, > Hajime > _______________________________________________ > pulseaudio-discuss mailing list > pulseaudio-discuss at lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss >
