Christoph-Sebastian Oesterheld writes: > Hello driver developers! > > Wich setting use the firmware for the PCMSEL bit 1 of the > audio decoder control register (AUD_CTRL_REG) in the TMS320AV7110: > > a) 0 for 16-bit PCM output or > b) 1 for 18-bit PCM output (default)? > > This difference is very important for the 16-bit Audio-DAC of my Siemens > DVB-C (rev. 1.5), > the AKM AK4309B > (http://www.asahi-kasei.co.jp/akm/en/product/ak4309b/ak4309b.html). > > The sound of the analog output of the Siemens DVB-C is not very good (like > an old 8-bit soundcard). > In contrast the sound of the SPDIF output is much better (tested with an > external connected DAC). > > I have compared the specs of the DSP and the DAC: > > In 18-bit PCM output mode, the audio decoder produce an 24-bit stream on the > PCM output. > The first 6 bits are zero, followed by the 18-bit PCM value. > The Audio-DAC ignores all preceding bits of an PCM bit stream with more than > 16 bits. > As a result the Audio DAC processed the lower 16 bits of the 18-bit PCM > values > and this is could be the reason for the badly sound. > > Over again, wich output precision use the firmware? > Can I force the 16-bit PCM output mode? > Perhaps my estimation is not correct an you have a better explanation? >
As far as I can see it audio is set to use 16-bit PCM during the initialization in the firmware. Since this is done thrugh an RTSL call I don't know if they set the control register bits in the way you described but I would guess so. Ralph -- Info: To unsubscribe send a mail to [EMAIL PROTECTED] with "unsubscribe linux-dvb" as subject.
