Thanks for giving attention to my problem. The hardware decoder is integrated in the logitech Z-5500 speakers. I don't have knowledge of any specific limit on the amount of data. There is however information regarding a maximum hw buffer size on the pulseaudio logs:
D: [pulseaudio] alsa-util.c: Trying a52:0 with SND_PCM_NO_AUTO_FORMAT ... D: [pulseaudio] alsa-util.c: Managed to open a52:0 D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Signed 32 bit Little Endian) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Signed 32 bit Big Endian) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Float 32 bit Little Endian) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Float 32 bit Big Endian) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Signed 32 bit Little Endian) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Signed 32 bit Big Endian) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Signed 24 bit Little Endian) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Signed 24 bit Big Endian) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Signed 24 bit Little Endian in 3bytes) failed: Invalid argument D: [pulseaudio] alsa-util.c: snd_pcm_hw_params_set_format(Signed 24 bit Big Endian in 3bytes) failed: Invalid argument D: [pulseaudio] alsa-util.c: Maximum hw buffer size is 320 ms D: [pulseaudio] alsa-util.c: Set buffer size first (to 3840 samples), period size second (to 480 samples). I: [pulseaudio] alsa-util.c: Device a52:0 doesn't support sample format s32le, changed to s16le. I: [pulseaudio] alsa-sink.c: Successfully opened device a52:0. I: [pulseaudio] alsa-sink.c: Selected mapping 'Digital Surround 5.1 (IEC958/AC3)' (iec958-ac3-surround-51). I: [pulseaudio] alsa-sink.c: Cannot enable timer-based scheduling, falling back to sound IRQ scheduling. I: [pulseaudio] alsa-sink.c: Successfully enabled mmap() mode. I: [pulseaudio] (alsa-lib)control.c: Invalid CTL a52:0 I: [pulseaudio] alsa-util.c: Unable to attach to mixer a52:0: No such file or directory I: [pulseaudio] alsa-sink.c: Failed to find a working mixer device. The dca plugin reports the same number of samples. Here is what I get from the dca plugin (heavier cpu usage): D: [pulseaudio] reserve-wrap.c: Successfully create reservation lock monitor for device 'Audio0' D: [pulseaudio] alsa-util.c: Trying dca:0 with SND_PCM_NO_AUTO_FORMAT ... D: [pulseaudio] alsa-util.c: Managed to open dca:0 I: [pulseaudio] alsa-util.c: Trying to disable ALSA period wakeups, using timers only D: [pulseaudio] alsa-util.c: Maximum hw buffer size is 341 ms D: [pulseaudio] alsa-util.c: Set buffer size first (to 96000 samples), period size second (to 96000 samples). I: [pulseaudio] alsa-util.c: ALSA period wakeups disabled I: [pulseaudio] alsa-sink.c: Successfully opened device dca:0. I: [pulseaudio] alsa-sink.c: Selected mapping 'Digital Surround 5.1 (IEC958/DTS)' (iec958-dts-surround-51). I: [pulseaudio] alsa-sink.c: Successfully enabled mmap() mode. I: [pulseaudio] alsa-sink.c: Successfully enabled timer-based scheduling mode. I: [pulseaudio] (alsa-lib)control.c: Invalid CTL dca:0 I: [pulseaudio] alsa-util.c: Unable to attach to mixer dca:0: No such file or directory I: [pulseaudio] alsa-util.c: Successfully attached to mixer 'hw:0' Note that the dca plugin finds mixer 'hw:0' while the a52 plugin doesn't. The dca.conf file is also a lot different from the a52.conf file. Here is the dca.conf: defaults.pcm.dca.aes0 0x06 defaults.pcm.dca.aes1 0x82 defaults.pcm.dca.aes2 0x00 defaults.pcm.dca.aes3 0x02 pcm.!dca { @args [ CARD DEV AES0 AES1 AES2 AES3 ] @args.CARD { type string default { @func getenv vars [ ALSA_IEC958_CARD ALSA_PCM_CARD ALSA_CARD ] default { @func refer name defaults.pcm.iec958.card } } } @args.DEV { type integer default { @func igetenv vars [ ALSA_IEC958_DEVICE ] default { @func refer name defaults.pcm.iec958.device } } } @args.AES0 { type integer default { @func refer name defaults.pcm.dca.aes0 } } @args.AES1 { type integer default { @func refer name defaults.pcm.dca.aes1 } } @args.AES2 { type integer default { @func refer name defaults.pcm.dca.aes2 } } @args.AES3 { type integer default { @func refer name defaults.pcm.dca.aes3 } } type dca slave.pcm { @func refer name { @func concat strings [ "cards." { @func card_driver card $CARD } ".pcm.iec958." $DEV ":" "CARD=" $CARD "," "AES0=" $AES0 "," "AES1=" $AES1 "," "AES2=" $AES2 "," "AES3=" $AES3 ] } } hint { show { @func refer name defaults.namehint.basic } description "DTS Encoding through IEC958 (S/PDIF)" device $DEV } } I haven't written these files. The developers did. I could try an a52.conf file identical to this one. But it might not work. It will depend of what the a52 plugin accepts. Anyway I will try it. I will keep you posted. Thanks again. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to pulseaudio in Ubuntu. https://bugs.launchpad.net/bugs/1188425 Title: Audio breaks up and pulseaudio eventually crashes with Alsa a52 (ac3) plugin (Ubuntu 13.04) Status in “pulseaudio” package in Ubuntu: New Bug description: I am encoding all audio in AC3 and sending it to my Logitech Z-5500 speakers through the SPDIF out jack on my laptop. Audio works fine for a while until it breaks up randomly and pulseaudio eventually crashes. By looking to the pulseaudio logs one can see some buffer underruns. I also tested with the 3.9.4 mainline kernel though I am not sure this issue is driver related. The result is always the same! I have this in /usr/share/alsa/alsa.conf.d/a52.conf pcm.a52 { @args [CARD] @args.CARD { type string } type rate slave { pcm { type a52 format S16_LE # S16_LE, S16_BE channels 6 # 2, 4, 6 bitrate 640 # 192, 224, 256, 320, 384, 448, 512, 576, 640 card $CARD } rate 48000 # 44100, 48000 } } One other thing I tried was the dcaenc-2 alsa plugin from this web page http://aepatrakov.narod.ru/index/0-2 and this plugin appears to not have the same problem. The disadvantage of the dca plugin is that it needs a lot more processing power! So I would prefer the a52 plugin if it worked flawlessly. These are the answers to the first two questions: 1) Ubuntu 13.04 2) libasound2-plugins-extra: Installed: 1.0.25-2ubuntu3 Candidate: 1.0.25-2ubuntu3 Version table: *** 1.0.25-2ubuntu3 0 500 http://pt.archive.ubuntu.com/ubuntu/ raring/universe amd64 Packages 100 /var/lib/dpkg/status To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1188425/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp