2018-05-25 22:15 GMT+08:00 Arun Raghavan <arun at arunraghavan.net>: > On Tue, 22 May 2018, at 4:32 PM, Alexander E. Patrakov wrote: >> There is some Microsoft documentation that contradicts this code. >> >> https://msdn.microsoft.com/en-us/library/windows/desktop/dd316761(v=vs.85).aspx >> >> """ >> Dolby TrueHD (MAT) >> >> Dolby TrueHD content is transmitted over IEC 60958 at 176.4 kHz / 8 >> channels (requiring an IEC 60958 frame rate of 705.6 kHz) for content >> sample rates of 44.1, 88.2 and 176.4 kHz, and 192 kHz / 8 channels >> (requiring an IEC 60958 frame rate of 768 kHz) for content sample >> rates of 48, 96 and 192 kHz. >> """ > > Based on Peter's input in a private thread, seems this is not the case on Linux: > > https://github.com/xbmc/xbmc/blob/master/xbmc/cores/AudioEngine/Sinks/AESinkALSA.cpp#L135 > https://github.com/xbmc/xbmc/blob/master/xbmc/cores/AudioEngine/Sinks/AESinkALSA.cpp#L486 I have looked, and also obtained a copy of IEC 61937-5-2006 standard, and I think I understand where this discrepancy comes from. The issue is that the standard does not define at all what to do if the sample rate of DTS audio is not a multiple of 48 kHz. I.e., it does not even cover the DTS CD case (44.1 kHz) that de-facto exists! Still, I think that diverging from what Windows does is not a good thing. Has anyone tested that passthrough works with DTS-HD streams that are not with a sample rate that is a multiple of 48 kHz? Does anyone have such DTS-HD stream at all? > > Cheers, > Arun > >> 2018-05-22 12:13 GMT+08:00 Arun Raghavan <arun at arunraghavan.net>: >> > In high bitrate mode, we force 192kHz/8ch as the sample format, which is >> > the expectation for HBR formats (as that is what allows for the largest >> > possible packet size). >> > --- >> > src/pulsecore/core-format.c | 3 +++ >> > 1 file changed, 3 insertions(+) >> > >> > diff --git a/src/pulsecore/core-format.c b/src/pulsecore/core-format.c >> > index 862a74b5d..096acc3a2 100644 >> > --- a/src/pulsecore/core-format.c >> > +++ b/src/pulsecore/core-format.c >> > @@ -248,6 +248,9 @@ int pa_format_info_to_sample_spec_fake(const pa_format_info *f, pa_sample_spec * >> > >> > if (f->encoding == PA_ENCODING_EAC3_IEC61937) >> > ss->rate *= 4; >> > + else if ((f->encoding == PA_ENCODING_TRUEHD_IEC61937) || >> > + (f->encoding == PA_ENCODING_DTSHD_IEC61937)) >> > + ss->rate = 192000; >> > >> > return 0; >> > } >> > -- >> > 2.17.0 >> > >> > _______________________________________________ >> > pulseaudio-discuss mailing list >> > pulseaudio-discuss at lists.freedesktop.org >> > https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss >> >> >> >> -- >> Alexander E. Patrakov -- Alexander E. Patrakov
