Raymond Yau wrote: > 2010/5/21 Clemens Ladisch <clemens@xxxxxxxxxx> > > Peter Ujfalusi wrote: > > > The DB_SCALE also provides linear mapping: > > > For example, if the HW volume control has a range 0 .. 100 > > > In HW these means: > > > 0 == -10dB, 1 == -9.8dB, 2 == -9.6dB .. 99 = 9.8dB, 100 = 10dB > > > So it is linear. > > > > This is not what is meant by "linear", because dB values are not linear. > > > > DB_LINEAR means that the mixer control value is a multiplier for the > > PCM sample value, as James wrote. A DB_LINEAR mapping has ... in practice ... > > 0 == -infinity dB, full scale == 0 dB, and the mapping between mixer > > control values and corresponding dB values it _not_ linear. > > > > TLV_DB_LINEAR_ITEM is a quite misleading name, but it actually means > > "dB mapping for a mixer control whose value has a linear effect on the > > sound output", _not_ a linear value <-> dB mapping. > > seem max(full scale) is more then 0dB for some codecs , only three drivers > have 0dB as max and TLV_DB_GAIN_MUTE (-99999.99dB) as min And these three are for hardware that use it as a plain multiplier. All the others seem to be mistakes: > soc/codecs/stac9766.c:static const DECLARE_TLV_DB_LINEAR(master_tlv, -4600, 0); > soc/codecs/stac9766.c:static const DECLARE_TLV_DB_LINEAR(record_tlv, 0, 2250); > soc/codecs/stac9766.c:static const DECLARE_TLV_DB_LINEAR(beep_tlv, -4500, 0); > soc/codecs/stac9766.c:static const DECLARE_TLV_DB_LINEAR(mix_tlv, -3450, 1200); These are wrong, both the AC'97 spec and the STAC9766 datasheet say that there is a linear register value/dB mapping; these should all use DECLARE_TLV_DB_SCALE. > soc/codecs/wm8350.c:static DECLARE_TLV_DB_LINEAR(pre_amp_tlv, -1200, 3525); > soc/codecs/wm8350.c:static DECLARE_TLV_DB_LINEAR(out_pga_tlv, -5700, 600); According to the datasheet, these should use DECLARE_TLV_DB_SCALE (like all the others in this file). > soc/codecs/wm8400.c:static const DECLARE_TLV_DB_LINEAR(rec_mix_tlv, -1500, 600); > soc/codecs/wm8400.c:static const DECLARE_TLV_DB_LINEAR(in_pga_tlv, -1650, 3000); > soc/codecs/wm8400.c:static const DECLARE_TLV_DB_LINEAR(out_mix_tlv, -2100, 0); > soc/codecs/wm8400.c:static const DECLARE_TLV_DB_LINEAR(out_pga_tlv, -7300, 600); > soc/codecs/wm8400.c:static const DECLARE_TLV_DB_LINEAR(out_omix_tlv, -600, 0); > soc/codecs/wm8400.c:static const DECLARE_TLV_DB_LINEAR(out_dac_tlv, -7163, 0); > soc/codecs/wm8400.c:static const DECLARE_TLV_DB_LINEAR(in_adc_tlv, -7163, 1763); > soc/codecs/wm8400.c:static const DECLARE_TLV_DB_LINEAR(out_sidetone_tlv, -3600, 0); > soc/codecs/wm8400.c: 0,7, TLV_DB_LINEAR_ITEM(-1200, 600), > soc/codecs/wm8990.c:static const DECLARE_TLV_DB_LINEAR(rec_mix_tlv, -1500, 600); > soc/codecs/wm8990.c:static const DECLARE_TLV_DB_LINEAR(in_pga_tlv, -1650, 3000); > soc/codecs/wm8990.c:static const DECLARE_TLV_DB_LINEAR(out_mix_tlv, 0, -2100); > soc/codecs/wm8990.c:static const DECLARE_TLV_DB_LINEAR(out_pga_tlv, -7300, 600); > soc/codecs/wm8990.c:static const DECLARE_TLV_DB_LINEAR(out_omix_tlv, -600, 0); > soc/codecs/wm8990.c:static const DECLARE_TLV_DB_LINEAR(out_dac_tlv, -7163, 0); > soc/codecs/wm8990.c:static const DECLARE_TLV_DB_LINEAR(in_adc_tlv, -7163, 1763); > soc/codecs/wm8990.c:static const DECLARE_TLV_DB_LINEAR(out_sidetone_tlv, -3600, 0); > soc/codecs/wm8990.c: 0, 7, TLV_DB_LINEAR_ITEM(-1200, 600), Same here. Regards, Clemens _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
