On 28.01.2012 02:31, Anssi Hannula wrote: > On 27.01.2012 16:12, Dominic Evans wrote: >> I have a digital S/PDIF output from my VDR frontend hooked up to a >> decent home amplifier and surround speakers. >> >> In the past I've had no problems using this via a vdr-sxfe frontend >> both for stereo MPEG-2 audio, as well as for 5.1 AC-3 on HD channels. >> >> audio.device.alsa_default_device:plughw:0,1 >> audio.device.alsa_front_device:plughw:0,1 >> audio.device.alsa_passthrough_device:plughw:0,1 >> audio.device.alsa_surround51_device:plughw:0,1 >> audio.output.speaker_arrangement:Pass Through >> >> However, recently (perhaps due to a kernel / alsa update?) I've found >> that I have to execute `iecset audio on` (to make analog MPEG-2 audio >> work) and `iecset audio off` (to make AC-3 passthrough work). >> >> Any idea why this might be? > > I'm not sure why it worked before (the most obvious reason would be a > different amplifier which doesn't care for the IEC/AES status bits, but > I'm sure you would've mentioned it if that was the case...). > > Instead of "plughw:0,1" for the devices, use e.g. symbolic "plug:iec958" > (may need CARD=foo parameter if you have multiple cards, in that case > look at "aplay -L" output for the correct value) for normal playback In case you or someone else needs the CARD=foo, the syntax to set ALSA device parameters when using the 'plug' plugin which I forgot to mention is: plug:'iec958:CARD=foo' or plug:"iec958:CARD=foo" > and > "iec958:AES0=0x06" for passthrough. And the reason I gave no "plug" for passthrough is that any automatic conversion done by the 'plug' plugin would corrupt the raw encoded audio data. > The "iec958" ALSA device will automatically set default IEC/AES values > when you open the device, making "iecset audio on" unnecessary. The > AES0=0x06 added for passthrough will do the same as "iecset audio off" > (i.e. it will set non-pcm bit 0x02 in the AES0 byte, default AES0 being > 0x04 (non-copyright bit)) for the duration of playback. > -- Anssi Hannula _______________________________________________ vdr mailing list vdr@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/vdr
